WO2019146900A1 - Direct current-direct current converter and power conversion method therefor - Google Patents

Abstract

A direct current-direct current converter, according to an embodiment, comprises: an overcurrent protection circuit unit connected to a first terminal; a direct current stabilization circuit unit connected to a second terminal; a bridge circuit unit electrically connected between the overcurrent protection circuit unit and the direct current stabilization circuit unit and including a switch; and a control unit for controlling the bridge circuit unit, wherein the control unit can determine an operating mode and a reference power according to the magnitude of the voltage of the first terminal.

Description

DC direct current converter and its power conversion method

Embodiments relate to an energy storage system including a DC / DC converter, a power supply system including the same, and a control method thereof.

Electrical energy is widely used because of its ease of conversion and transmission. In order to efficiently use electric energy, an energy storage system (ESS) is used. The energy storage system is powered and charges the battery. In addition, the energy storage system discharges the electric power charged in the battery to supply electric power when necessary. This allows the energy storage system to supply power flexibly.

Specifically, when the power supply system includes an energy storage system, it operates as follows. The energy storage system discharges electrical energy stored in the battery when the load or system is overloaded. Also, when the load or system is light, the energy storage system receives power from the generator or system and charges the battery.

Also, when the energy storage system is independent of the power supply system, the energy storage system receives the idle power from the external power supply and charges the battery. Also, when the system or the load is overloaded, the energy storage system discharges the charged power from the battery to supply power.

Meanwhile, the energy storage system must initially charge (or precharge) the DC link voltage disposed at the inverter input terminal of the power supply system during the battery discharge mode operation to reduce the voltage difference between the battery side and the inverter side and shut off the inrush current. To initial charge the DC link voltage, the power supply system was supplied with the initial charging power from the generator or system.

However, when there is no generated generated power and the initial charge power is not supplied from the power generation apparatus and the initial charge power supply in the system is interrupted, the energy storage system fails to initial charge the DC link voltage.

Also, in the energy storage system, when the DC / DC converter performs power conversion, the power conversion efficiency varies depending on the ratio of the output power. In particular, the DC / DC converter has a problem that the power conversion efficiency sharply decreases below a predetermined ratio of the output power. As a result, the energy storage system has a problem in that energy supply or supply and demand efficiency of the battery is reduced.

Also, when the battery is discharged, the energy storage system drives the DC / DC converter to charge the battery. In this case, the DC / DC converter was supplied with standby power from the battery for driving. However, when the battery is completely discharged or overdischarged, the energy storage system can not operate the DC / DC converter because the standby power is not supplied from the battery, and the battery needs to be replaced.

In addition, the energy storage system performs a droop control in order to improve the stability in charging or discharging operation of the battery. In particular, the energy storage system controls the droop according to the state of charge (SOC) of the battery. However, in order to control the droop according to the state of charge (SOC) of the battery, a communication line and a communication unit for communicating with the BMS of the battery were separately needed, and the stability of the charging or discharging operation of the battery was improved There was a limit.

The embodiments are designed to solve the problems of the prior art described above, and an object of the present invention is to provide an energy storage system including a DC / DC converter, a power supply system including the same, and a control method thereof.

In addition, the embodiment provides an energy storage system including a DC / DC converter capable of initially charging a DC link voltage without any other configuration, a power supply system including the same, and a control method thereof.

In addition, the embodiment provides an energy storage system including a DC / DC converter excellent in power conversion efficiency, a power supply system including the same, and a control method thereof.

In addition, the embodiment provides an energy storage system including a DC / DC converter capable of charging a battery without battery replacement even if the battery is overdischarged, a power supply system including the DC / DC converter, and a control method thereof.

Further, an embodiment provides an energy storage system including a DC / DC converter for quickly determining an operation mode of charging or discharging a battery, a power supply system including the same, and a control method thereof.

In addition, the embodiment provides an energy storage system including a DC / DC converter that does not require a separate communication line and a communication unit for controlling charging or discharging of a battery, a power supply system including the same, and a control method thereof.

Also, an embodiment provides an energy storage system including a DC / DC converter capable of rapid droop control when a battery is charged or discharged, a power supply system including the same, and a control method thereof.

The technical problems to be solved by the embodiments are not limited to the technical problems mentioned above, and other technical problems which are not mentioned can be clearly understood by those skilled in the art from the following description. There will be.

According to an aspect of the present invention, there is provided a DC / DC converter including: an overcurrent protection circuit connected to a first end; A DC stabilization circuit portion connected to the second stage; A bridge circuit part electrically connected between the overcurrent protection circuit part and the DC stabilization circuit part and including a switch; And a control unit for controlling the bridge circuit unit, wherein the controller can determine the operation mode and the reference power according to the magnitude of the voltage of the first stage.

Further, in the DC / DC converter according to the embodiment, the control unit may provide the bridge circuit with a switching signal for controlling the switch based on the determined reference power.

Also, in the DC / DC converter according to the embodiment, the DC link capacitor may be connected to the first end.

In the DC / DC converter according to the embodiment, the operation mode is a charge mode when the voltage of the first stage is equal to or higher than the first voltage, the voltage of the first stage is lower than the first voltage, And if the voltage of the first stage is lower than the second voltage, it may be a discharge mode.

In the DC / DC converter according to the embodiment, the reference power is calculated by subtracting the first voltage from the voltage of the first end and multiplying by the charge power slope when the operation mode is the charge mode, In the discharge mode, the first voltage may be subtracted from the second voltage and then multiplied by the discharge power slope.

In the DC / DC converter according to the embodiment, if the determined reference power is greater than a set maximum power, the control unit generates the switching signal based on the maximum power. If the determined reference power is greater than the inverter limited power, Generate the switching signal based on the inverter limited power, and generate the switching signal based on the battery limited power if the determined reference power is greater than the battery limiting power.

A power conversion method according to an embodiment includes: sensing a voltage of a first stage; Selecting an operation mode according to the magnitude of the voltage of the first stage; Determining a reference power according to the magnitude of the voltage of the first stage; And generating a switching signal based on the determined reference power, wherein the switching signal is a signal for controlling a switch constituting a bridge circuit based on the determined reference power, the voltage of the first stage Is the voltage of the DC link capacitor in the first stage.

The operation mode may be a standby mode if the voltage of the first stage is lower than the first voltage and higher than the second voltage, And the discharge mode if the voltage is lower than the second voltage.

The reference voltage may be calculated by subtracting the first voltage from the first voltage and multiplying the first voltage by the charge power slope if the operation mode is the charge mode. If the operation mode is the discharge mode, Is calculated by subtracting the voltage of the first stage and then multiplying by the discharge power slope.

The generating of the switching signal may further include generating the switching signal based on the maximum power if the determined reference power is greater than the set maximum power and if the determined reference power is greater than the inverter limited power, And generating the switching signal based on the battery limiting power if the determined reference power is greater than the battery limiting power.

The energy storage system including the DC / DC converter according to the embodiment, the power supply system including the DC / DC converter, and the control method thereof will be described as follows.

The embodiment can initially charge the DC link voltage without any other configuration.

In addition, since the initial charging speed of the DC link voltage is fast in the embodiment, the battery discharging operation can be speeded up.

In addition, the embodiment can have excellent power conversion efficiency of the DC / DC converter.

In addition, the embodiment can have a high power conversion efficiency of the DC / DC converter, and thus can have a high energy efficiency when the battery is charged or discharged.

In addition, the embodiment can charge the battery even if the battery is overdischarged.

Further, the embodiment does not need to replace the battery even if the battery is overdischarged. The embodiment can quickly determine the operation mode of the charging or discharging of the battery.

In addition, the embodiment does not require a separate communication line and a communication unit for controlling charging or discharging of the battery.

In addition, the embodiment is capable of rapid droop control when the battery is charged or discharged.

The effects obtained in the embodiments are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. It is to be noted, however, that the technical features of the embodiments are not limited to the specific drawings, and the features disclosed in the drawings may be combined with each other to constitute a new embodiment.

1 is a view for explaining a schematic configuration of a power supply system according to an embodiment.

2 is a view for explaining an energy storage system according to an embodiment.

3 is a graph illustrating a DC voltage and a DC current of a DC link capacitor at the time of initial charging according to an exemplary embodiment.

4 is a circuit diagram of a DC / DC converter according to an embodiment.

5 illustrates the operation of the DC / DC converter of FIG. 4 to initially charge the DC link capacitor.

FIG. 6 illustrates the operation of the DC / DC converter of FIG. 4 for initial charging the DC link capacitor.

7 is a circuit diagram of a DC / DC converter according to another embodiment.

FIG. 8 illustrates the operation of the DC / DC converter of FIG. 7 for initial charging the DC link capacitor.

FIG. 9 illustrates the operation of the DC / DC converter of FIG. 7 for initial charging the DC link capacitor.

10 is a circuit diagram of a DC / DC converter according to another embodiment.

11 is a graph showing power conversion ratios according to output power ratios in DC power conversion of an energy storage system according to an exemplary embodiment.

12 is a view for explaining a pulse width control method of a DC / DC converter of an energy storage system according to an embodiment.

13 is a diagram for explaining a signal according to the output power of the energy storage system according to an embodiment.

14 is a view for explaining an initial charging method of a DC link capacitor of a power supply system according to an embodiment.

15 is a view for explaining a power supply method of an energy storage system according to an embodiment.

16 is a view for explaining a configuration of a converter efficiency control unit applied to an energy storage system of a power supply system according to an embodiment.

17 is a diagram for explaining a power conversion efficiency control method of a DC / DC converter of an energy storage system according to an embodiment.

18 is a view for explaining an energy storage system according to another embodiment.

19 is a view for explaining an energy storage system according to another embodiment.

20 is a view for explaining an energy storage system according to another embodiment.

FIG. 21 is a view for explaining an energy storage system according to another embodiment.

22 is a diagram for explaining a power conversion method for charging a battery in a DC / DC converter of an energy storage system according to an embodiment.

23 is a view for explaining an energy storage system according to another embodiment.

FIG. 24 is a diagram for explaining the control unit of FIG. 23. FIG.

FIG. 25 is a diagram for explaining a droop control curve of the energy storage system of FIG. 23. FIG.

FIG. 26 is a diagram for explaining the reference current determination unit of FIG. 24; FIG.

FIG. 27 is a diagram for explaining the current control section of FIG. 24. FIG.

FIG. 28 is a diagram for explaining a power conversion method of the energy storage system of FIG. 23. FIG.

FIG. 29 is a diagram for explaining a method of selecting the operation mode of FIG. 28; FIG.

FIG. 30 is a diagram for explaining a method of determining the reference power in FIG.

Hereinafter, embodiments related to the present invention will be described in detail with reference to the drawings. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

Combinations of the steps of each block and flowchart in the accompanying drawings may be performed by computer program instructions. These computer program instructions may be embedded in a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus so that the instructions, which may be executed by a processor of a computer or other programmable data processing apparatus, Thereby creating means for performing the functions described in the step. These computer program instructions may also be stored in a computer usable or computer readable memory capable of directing a computer or other programmable data processing apparatus to implement the functionality in a particular manner so that the computer usable or computer readable memory It is also possible to produce manufacturing items that contain instruction means that perform the functions described in each block or flowchart illustration in each step of the drawings. Computer program instructions may also be stored on a computer or other programmable data processing equipment so that a series of operating steps may be performed on a computer or other programmable data processing equipment to create a computer- It is also possible for the instructions to perform the processing equipment to provide steps for executing the functions described in each block and flowchart of the drawings.

Also, each block or each step may represent a module, segment, or portion of code that includes one or more executable instructions for executing the specified logical function (s). It should also be noted that in some alternative embodiments, the functions mentioned in the blocks or steps may occur out of order. For example, two blocks or steps shown in succession may in fact be performed substantially concurrently, or the blocks or steps may sometimes be performed in reverse order according to the corresponding function.

1 is a view for explaining a schematic configuration of a power supply system according to an embodiment.

1, a power supply system 1 according to an embodiment includes a generator 10, an energy storage system 20, an inverter 30, an AC filter 40, an AC / AC converter 50, (60), a system control unit (80), and a load (70).

The power generation apparatus 10 can produce electric energy. When the power generation apparatus 10 is a solar power generation system, the power generation apparatus 10 may be a solar cell array. A solar cell array is a combination of a plurality of solar cell modules. The solar cell module may be a device that connects a plurality of solar cells in series or in parallel to convert solar energy into electrical energy to generate a predetermined voltage and current. Thus, a solar cell array can absorb solar energy and convert it into electrical energy. When the power generation apparatus 10 is a wind power generation system, the power generation apparatus 10 may be a fan that converts wind energy into electric energy.

Meanwhile, the power generation device 10 is not limited to the solar power generation system and the wind power generation system, and may be a tidal power generation system. However, this is an example, and the power generation apparatus 10 is not limited to the above-mentioned kind, and may include all power generation systems that generate electric energy by using renewable energy such as solar heat or geothermal heat.

In addition, the power supply system 1 can supply power only through the energy storage system 20 without the power generation apparatus 10. [ In this case, the power supply system 1 may not include the power generation apparatus 10. [

The inverter 30 can convert DC power into AC power. More specifically, the DC power supplied by the power generation apparatus 10 or the DC power discharged by the energy storage system 20 can be converted into AC power.

The AC filter 40 can filter the noise of the power converted into the AC power. Further, the AC filter 40 may be omitted according to the embodiment.

The AC / AC converter 50 converts the magnitude of the voltage of the AC filtered noise so that the AC power can be supplied to the system 60 or the load 70 and converts the converted AC power into the system 60 or the load 70). Further, the AC / AC converter 50 may be omitted according to the embodiment.

The system 60 is a system in which many power plants, substations, transmission / distribution lines, and loads are integrated to generate and utilize electric power.

The load 70 may be supplied with electric energy from the power generation system such as the power generation apparatus 10 or the energy storage system 20 to consume electric power.

The energy storage system 20 can charge the electric energy supplied from the power generation device 10 and discharge the charged electric energy according to the power supply status of the system 60 or the load 70 . More specifically, when the system (60) or the load (70) is light load, the energy storage system (20) can receive and charge the idle power from the power generation device (10). When the system 60 or the load 70 is overloaded, the energy storage system 20 can provide power to the system 60 or the load 70 by discharging the charged power. The energy storage system 20 may also be connected between the generator device 10 and the inverter 30 so as to be electrically connected to the generator device 10 and electrically connected to the inverter device 30.

The system control unit 80 can control the operation of the energy storage system 20, the inverter 30, and the AC / AC converter 50. More specifically, the system control unit 80 can control the charging and discharging of the energy storage system 20. If the system 60 or the load 70 is overloaded, the system control 80 can control the energy storage system 20 to supply power to the system 60 or the load 70 . When the system 60 or the load 70 is light, the system control unit 80 can control the external power supply or the power generation apparatus 10 to supply power to the energy storage system 20.

Hereinafter, the energy storage system will be described in more detail.

2 is a view for explaining an energy storage system according to an embodiment.

Referring to FIG. 2, the energy storage system 20 according to one embodiment may include a DC / DC converter 100, a battery 200, and a charge controller 300. Although not shown in FIG. 1, the energy storage system 20 may be coupled to the inverter 30 via a DC link capacitor 90. That is, the DC link capacitor 90 may be disposed between the energy storage system 20 and the inverter 30. [ The energy storage system 20 may receive the DC voltage Vdc of the DC link capacitor 90 in the charge mode and provide the DC voltage Vdc to the DC link capacitor 90 in the discharge mode.

The battery 200 receives the charging power from the DC / DC converter 100 in the charging mode, and can perform the charging operation by the received power. Also, the battery 200 may output the stored power to the DC / DC converter 100 in the discharge mode. In addition, the battery 200 may include a plurality of battery cells for performing the charging operation and the discharging operation.

The charge control unit 300 may include a battery management system (BMS). The charge control unit 300 may provide the system control unit 80 with battery state information on the state of the battery 200. [ For example, the charge control unit 300 monitors at least one of the voltage, current, temperature, remaining power, and charge state of the battery 200, and transmits status information of the monitored battery 200 to the system control unit 80 . In addition, the charge controller 300 may be configured to allow a plurality of battery cells to maintain an appropriate voltage while charging or discharging. Further, the charge control unit 300 can operate based on the control signal of the system control unit 80. [ Also, the charge controller 300 may control the DC / DC converter 100 according to the status information of the battery 200 that is monitored. Also, the charge controller 300 may control the DC / DC converter 100 according to the charge mode or the discharge mode. More specifically, the charge controller 300 provides a charge control signal or a discharge control signal for controlling the DC / DC converter 100 to the converter controller of the DC / DC converter 100, and the DC / DC converter 100, The converter control unit of the DC / DC converter 100 may provide the PWM signal to the switch of the DC / DC converter 100 based on the charge control signal or the discharge control signal. Also, the charge control unit 300 may control the DC / DC converter 100 for initial charging of the DC link capacitor 90 in the discharge mode of the battery 200. That is, the charge control unit 300 provides an initial charge control signal for controlling the DC / DC converter 100 to the converter control unit of the DC / DC converter 100, and the converter control unit of the DC / It is possible to provide the initial charge switch signal to the switch of the DC / DC converter 100 based on the charge control signal. Also, the charge control unit 300 may control the DC / DC converter 100 to increase the power conversion efficiency of the DC / DC converter 100. [ More specifically, the charge controller 300 provides the converter control unit of the DC / DC converter 100 with a power conversion efficiency control signal that can increase the power conversion efficiency of the DC / DC converter 100, and the DC / 100 may provide the PWM signal to the switch of the DC / DC converter 100 based on the power conversion efficiency control signal.

The DC / DC converter 100 can convert the magnitude of the DC power supplied by the energy storage system 20 in the charging mode or in the discharging mode. More specifically, the DC / DC converter 100 converts the DC power supplied from the power generator 10 or the inverter 30 to the DC link capacitor 90 into a voltage magnitude for charging the battery 200, 200). Also, the DC / DC converter 100 may convert the DC voltage provided by the battery 200 into a voltage magnitude that the inverter 30 can use, and provide the DC voltage to the DC link capacitor 90.

<Initial Charging of DC Link Capacitor>

3 is a graph illustrating a DC voltage and a DC current of a DC link capacitor at the time of initial charging according to an exemplary embodiment.

The energy storage system 20 according to one embodiment does not need a separate configuration for the initial charging of the DC link capacitor 90 for the discharge mode operation. The energy storage system 20 supplies the electric energy stored in the battery 200 to the DC link capacitor 90 by the switching operation of the DC / DC converter 100 so that the DC voltage of the DC link capacitor 90 is supplied to the inverter 30 Up to the operating voltage of the battery. More specifically, the DC / DC converter 100 may provide the DC current Idc to the DC link capacitor 90. [ The DC link capacitor 90 may be charged with a direct current (Idc), so that the direct current voltage (Vdc) may rise. The DC / DC converter 100 may initially charge the DC voltage Vdc to an operating voltage at which the inverter 30 can invert during the initial charge period. For example, as shown in FIG. 3, the DC / DC converter 100 turns on or off the switch to turn on the DC current Idc of the predetermined level I1 for a plurality of periods T1, T2, and T3 , T4). If the DC current Idc is continuously supplied to the initial charge period Ti, the voltage difference between the inverter 30 and the DC / DC converter 100 may cause a problem of circuit damage. Therefore, the DC / DC converter 100 can provide the DC current Idc to the DC link capacitor 90 in a plurality of periods. The plurality of periods in which the direct current Idc is provided may all be the same period. However, the present invention is not limited to this. As the DC voltage Vdc increases, the voltage of the inverter 30 and the voltage difference of the DC / DC converter 100 decrease, thereby increasing the duration of the DC current Idc. In this case, the initial charge time can be reduced. As the DC current Idc is provided, the DC voltage Vdc increases. The DC / DC converter 100 terminates the initial charge when the DC voltage Vdc reaches the operating voltage V1 and performs the boosting operation in the discharge mode. When the DC / DC converter 100 performs the boosting operation, it can reach the second DC voltage level V2.

Also, the method of initial charging by the DC / DC converter 100 may include an initial charging method of the DC link capacitor of FIG.

Hereinafter, the initial charging of the DC link capacitor 90 will be described according to a specific embodiment of the DC / DC converter 100. FIG.

FIG. 4 is a circuit diagram of a DC / DC converter according to an embodiment, and FIGS. 5 and 6 illustrate an operation for initial charging a DC link capacitor of the DC / DC converter of FIG.

Referring to FIG. 4, the DC / DC converter 100 according to an embodiment is a bidirectional DC / DC converter, and may be an isolated converter.

The DC / DC converter 100 according to an exemplary embodiment may include a controller 130. The control unit 130 may generate a PWM signal based on the control signal provided from the charge control unit 300 and provide the generated PWM signal to the bridge circuit unit 120 including the switch.

The DC / DC converter 100 according to an exemplary embodiment may include the overcurrent protection circuit unit 110. FIG. The overcurrent protection circuit unit 110 can prevent EOS or overcurrent flowing into the energy storage system 20 or flowing out to the outside. The overcurrent protection circuit part 110 may be disposed between the first end connected to the DC link capacitor 90 and the bridge circuit part 120. Also, the overcurrent protection circuit unit 110 may include a circuit breaker. In this case, the overcurrent protection circuit unit 110 may open between the first stage and the bridge circuit unit 120 when EOS or an overcurrent flows into the energy storage system 20. FIG. The DC / DC converter 100 may include a bridge circuit unit 120. The DC / DC converter 100 may include a bridge circuit unit 120 and an overcurrent protection circuit unit 110. The overcurrent protection circuit unit 110 may block the input / The bridge circuit unit 120 may include a transformer T, a first full bridge circuit 121, and a second full bridge circuit 122. [ The bridge circuit unit 120 is divided into a primary circuit on the left side and a secondary circuit on the right side based on the transformer T made up of the first and second coils LP and Ls, And the switch elements Q1 to Q4 constituting the full bridge circuit 121. [ The secondary circuit may include a second full bridge circuit 122 composed of a DC stabilization circuit part 140 composed of a second capacitor C2 and a second inductor L2 and switch elements Q5 to Q8 . The DC stabilization circuit unit 140 may be connected to a second end to which the battery 200 is connected.

In the primary side circuit, the first coil Lp is connected between the third node N3 and the fourth node N4. The first full bridge circuit 121 includes a first leg and a second leg between the first and second nodes N1 and N2 and the first leg is connected to the first and third nodes N1, N3 and a second switch element Q2 connected between the third node N3 and the second node N2 and the second leg comprises a first switch element Q1 connected between the first node N3 and the second node N2, A third switch element Q3 connected between the first node N1 and the fourth node N4 and a fourth switch element Q4 connected between the fourth node N4 and the second node N2.

The battery 200 and the second capacitor C2 are connected between the fifth and sixth nodes N5 and N6 in the secondary side circuit and the second inductor L2 is connected between the fifth and seventh nodes N5 and N7, And the second coil Ls is connected between the tenth and ninth nodes N10 and N9. And the second full bridge circuit 122 comprises a third leg and a fourth leg between the seventh and eighth nodes N7 and N8 and the third leg is connected between the seventh and ninth nodes N7 and N9 And a sixth switch element Q6 connected between the ninth and eighth nodes N9 and N8 and the fourth leg is connected to the seventh and tenth nodes N7 and N10 And an eighth switch element Q8 connected between the tenth and eighth nodes N10 and N8.

The DC-DC converter 100 according to an exemplary embodiment is a bi-directional converter. In the step-down mode, the DC input voltage on the first and second nodes N1 and N2 is lowered to the fifth and sixth The DC output voltage is output to the nodes N5 and N6 and the DC input voltage on the fifth and sixth nodes N5 and N6 is increased in the step up mode to increase the voltage of the first and second nodes N1 and N6 , And N2, respectively.

The DC-DC converter 100 according to the embodiment performs the switching operation of the first full bridge circuit 121 and the second full bridge circuit 122 for initial charging of the DC link capacitor 90 for the discharge mode It is possible to provide the DC current Idc to the DC link capacitor 90. 5, the Nth (N is a natural number) DC current Idc of the plurality of DC current Idc provided in the initial charging is input to the seventh switching device Q7 of the second full bridge circuit 122 And the sixth switch element Q6 are turned on and the fifth switch element Q5 and the eighth switch element Q8 are turned off so that the first switch element Q1 and the fourth switch element Q2 of the first full bridge circuit 121 are turned off, The switch element Q4 may be turned on and the second switch element Q2 and the third switch element Q3 may be turned off. 6, the (N + 1) th (N is a natural number) direct current Idc of the plurality of direct current Idc provided in the initial charge is supplied to the fifth switch element Q5 of the second full bridge circuit 122, And the eighth switch element Q8 are turned on and the sixth switch element Q6 and the eighth switch element Q8 are turned off so that the third switch element Q3 of the first full bridge circuit 121, The element Q2 may be turned on and the first switch element Q1 and the fourth switch element Q4 may be turned off.

FIG. 7 is a circuit diagram of a DC / DC converter according to another embodiment, and FIGS. 8 and 9 illustrate operations for initial charging the DC link capacitor of the DC / DC converter of FIG.

Referring to FIG. 7, the DC / DC converter 1100 according to another embodiment is a bidirectional DC / DC converter, and may be a non-isolated converter.

The DC / DC converter 1100 according to another embodiment may include a controller 1130. The control unit 1130 generates a PWM signal based on the control signal provided from the charge control unit 300 and provides the generated PWM signal to the top switch unit 1150 or the bridge circuit unit 1120 including the switch.

The DC / DC converter 1100 according to another embodiment may include the overcurrent protection circuit portion 1110. The overcurrent protection circuit part 1110 can prevent EOS or overcurrent flowing into the energy storage system 20 or flowing out to the outside. The overcurrent protection circuit portion 1110 may be disposed between the top switch portion 1150 to which the DC link capacitor 90 is connected. In addition, the overcurrent protection circuit portion 1110 may include a circuit breaker. In this case, the overcurrent protection circuit portion 1110 can open between the first stage and the top switch portion 1150 when EOS or an overcurrent flows into the energy storage system 20. Thus, the overcurrent protection circuit portion 1110 can block the input / output of the current to / from the energy storage system 20.

The DC / DC converter 1100 according to another embodiment may include a top switch unit 1150. The top switch unit 1150 may be disposed between the overcurrent protection circuit unit 1110 and the bridge circuit unit 1120. Further, the top switch unit 1150 may include a thirteenth switch element Q13.

The DC / DC converter 1100 according to another embodiment may include a bridge circuit unit 1120. The bridge circuit portion 1120 may be disposed between the top switch portion 1150 and the DC stabilization circuit portion 1140. The bridge circuit portion 1120 may include a ninth switch element to a twelfth switch element Q9 to Q12.

The DC / DC converter 1100 according to another embodiment may include the DC stabilization circuit portion 1140. The DC stabilization circuit unit 1140 may include a 2-1 inductor L21, a 2-2 inductor L22, and a second capacitor C2. The DC stabilization circuit unit 1140 may be connected to a second end of the battery 200 connected to the DC stabilization circuit unit 1140.

The top switch unit 1150 is connected between one side of the overcurrent protection circuit unit 1110 and the eleventh node N11. The battery 200 and the second capacitor C2 are connected between the 15th and 16th nodes N15 and N16 and the 2-1 inductor L2-1 is connected between the 15th and 13th nodes N15 and N13, And the 2-2 inductor L2-2 is connected between the 15th node and the 14th node N15, N14. The bridge circuit unit 1120 includes an eleventh leg and a twelfth leg between the eleventh and twelfth nodes N11 and N12 and the eleventh leg is connected between the eleventh and thirteenth nodes N11 and N13 And the twelfth switch element Q12 connected between the eleventh and twelfth nodes N11 and N12 connected between the eleventh and twelfth nodes N13 and N12. And a tenth switching element Q10 connected between the fourteenth and twelfth nodes N14 and N12.

The DC-DC converter 1100 according to another embodiment is a bidirectional converter. In the step-down mode, the DC-DC converter 1100 drops the DC input voltage on the DC link capacitor 90 to the 15th and 16th nodes N15 and N16 In the step-up mode, the dc input voltage on the fifteenth and sixteenth nodes N15 and N16 is raised to output the dc output voltage to the dc link capacitor 90 .

The DC-DC converter 1100 according to another embodiment performs the switching operation of the top switch part 1150 and the bridge circuit part 1120 for initial charging of the DC link capacitor 90 for the discharge mode, The DC current Idc can be supplied to the DC power supply Ip. 8, the Nth (N is a natural number) DC current Idc of a plurality of DC currents Idc provided in the initial charge can be obtained by turning on the eleventh switch element Q11 of the bridge circuit unit 1120 The tenth switch element Q10 and the twelfth switch element Q12 are turned off and the thirteenth switch element Q13 of the top switch section 1150 is turned on. 9, the (N + 1) th (N is a natural number) DC current Idc of the plurality of direct current Idc provided in the initial charge is turned on when the ninth switch element Q9 of the bridge circuit portion 1120 is turned on The eleventh switch element Q11, the tenth switch element Q10 and the twelfth switch element Q12 may be turned off and the thirteenth switch element Q13 of the top switch portion 1150 may be turned on. In addition, the thirteenth switching element Q13 of the top switch unit 1150 can be turned off while the direct current Idc for charging the gun is not supplied.

10 is a circuit diagram of a DC / DC converter according to another embodiment.

Referring to FIG. 10, the DC / DC converter of FIG. 10 is the same as the DC / DC converter of FIG. 7 except for the top switch unit 2150. Therefore, description of the same configuration as the DC / DC converter of Fig. 7 will be omitted.

The top switch unit 2150 according to another embodiment may include a main switch unit 2151 and an initial charge switch unit 2152. The main switch unit 2151 may include a thirteenth switch element Q13 disposed between the one end of the overcurrent protection circuit unit 2110 and the eleventh node N11. The initial charge switch unit 2152 may be connected in parallel with the main switch unit 2151. The initial charge switch portion 2152 may include a fourteenth switch element Q14 and a resistor R. [ One side of the fourteenth switch element Q14 may be connected to one end of the overcurrent protection circuit portion 2110 and the other side thereof may be connected to one side of the resistor R. [ The resistor R may have one side connected to the other side of the fourteenth switching device Q14 and the other side connected to the eleventh node N11. So that the electric current of the charging switch unit 2152 can flow to the initial charging switch unit 2152.

The DC / DC converter 2100 according to another embodiment of the present invention may be configured such that the main switch unit 2151 is turned on / off and the initial charge switch unit 2152 is turned on when the DC / DC converter 2100 operates in the step- Can maintain the OFF state. Also, the DC / DC converter 1100 may maintain the off state of the main switch unit 2151 and turn on / off the initial charge switch unit 2152 in the initial charge mode before starting the discharge mode. That is, when the DC / DC converter 2100 according to another embodiment initializes the DC link capacitor 90, the operation of the bridge circuit unit 2120 is the same as that of the bridge circuit unit 1120 of the DC / DC converter 1100 of FIG. May be the same as the operation of Fig.

Accordingly, the energy storage system according to the embodiment can charge the DC link capacitor before discharging mode operation without any other configuration. In addition, the energy storage system according to the embodiment can increase the DC current provided to the DC link capacitor gradually to accelerate the initial charging speed and accelerate the battery discharging operation.

<Converter efficiency control>

FIG. 11 is a graph showing a power conversion ratio according to an output power ratio at the time of DC direct power conversion by the energy storage system according to an embodiment. FIG. 12 is a graph illustrating a pulse width control method of a DC / And FIG. 13 is a view for explaining a signal according to an output power of the energy storage system according to an embodiment.

Referring to FIG. 11, in a DC / DC converter, power conversion efficiency (dotted line) is drastically lowered when the output power is lower than a predetermined ratio P1 during power conversion. For example, a DC / DC converter has a power conversion efficiency of less than 95% at power conversion with less than 25% of maximum output power.

The energy storage system 20 according to the embodiment can maintain the power conversion efficiency (solid line) at a predetermined efficiency even when the output power of the DC / DC converter becomes a predetermined ratio P1 or less. For example, a dc / dc converter can maintain a power conversion efficiency of 95% at power conversion with less than 25% of maximum output power. To this end, the DC / DC converter 100 can provide a DC current Idc having a high power conversion efficiency when the DC / DC converter 100 becomes a predetermined ratio P1 or less of the maximum output power during power conversion. In this case, the output power can be adjusted by controlling the pulse width of the PWM signal controlling the DC / DC converter 100. [ Also, the DC current Idc provided at a predetermined ratio (P1) or less of the maximum output power has a problem that the current ripple increases as the intensity increases, so that the current intensity can be set to satisfy the predetermined ripple range. More specifically, referring to FIG. 12, the DC / DC converter 100 may be provided with a PWM signal used for power conversion in a charge mode or a discharge mode operation from the converter control unit. The pulse width of the PWM signal may be set to the first pulse width W1 during a period Tw during which the DC / DC converter 100 outputs the output power at a predetermined ratio P1 or more of the maximum output power. In this case, the intensity of the output power can be adjusted by adjusting the intensity of the direct current Idc. Also, the pulse width can be adjusted to the second pulse width W2 during a period Tw during which the DC / DC converter 100 outputs the output power with the PWM signal less than the predetermined ratio P1 of the maximum output power have. In this case, the intensity of the output power can be adjusted by adjusting the pulse width of the PWM signal while maintaining the intensity of the DC current Idc whose power conversion efficiency is equal to or higher than the predetermined efficiency. 13, (a) shows a case where the DC / DC converter 100 outputs an output power of 300 W, (b) shows a case where the DC / DC converter 100 outputs an output power of 900 W . the DC / DC converter 100 of FIGS. 2A and 2B is maintained at the intensity of the DC current Idc whose power conversion efficiency is higher than a predetermined efficiency, and the pulse widths of the PWM signals are different from each other. That is, the PWM signal of the DC / DC converter 100 is larger than the pulse width for outputting the power of 300 W of pulse width for outputting 900 W power.

In addition, a method of controlling the power conversion efficiency of the DC / DC converter 100 may include the converter efficiency control method of FIGS. 15 to 17. FIG.

Therefore, the energy storage system according to one embodiment can have excellent power conversion efficiency of the DC / DC converter. In addition, the energy storage system according to an exemplary embodiment has a high power conversion efficiency of the DC / DC converter, so that energy efficiency to be transferred when the battery is charged or discharged can be high.

14 is a view for explaining an initial charging method of a DC link capacitor of a power supply system according to an embodiment.

Referring to FIG. 14, the power supply system may include starting a battery discharge mode of the energy storage system (S1410). That is, the system control unit may transmit a command signal to the energy storage system to inform the discharge mode operation.

The power supply system may include determining whether the DC voltage is equal to or higher than the operating voltage (S1420). More specifically, the charge control unit of the energy storage system can determine whether the DC voltage of the DC link capacitor is higher than an operating voltage capable of performing an inverting operation of the inverter.

The power supply system may include performing a discharging operation of the battery (S1430) if the DC voltage is equal to or higher than the operating voltage. More specifically, the DC / DC converter performs a boosting operation to increase the DC input voltage provided by the battery to provide a DC voltage to the DC link capacitor.

The power supply system may include initiating an initial charge mode if the DC voltage is below the operating voltage (S1440).

The power supply system may include providing an initial charge current to the DC link capacitor when starting the initial charge mode (S1450). That is, the DC / DC converter of the energy storage system can provide the DC current to the DC link capacitor using the electric energy of the battery. In this case, a method in which the DC / DC converter of Figs. 3 to 10 initially charges the DC link capacitor can be used.

While the initial charge current is being provided, the power supply system may include determining whether the DC voltage is greater than the operating voltage (S1460). In this case, if the DC voltage is equal to or higher than the operating voltage, the DC / DC converter can terminate the initial charging mode and perform the discharging operation of the battery (S1430).

While the initial charge current is being supplied, the power supply system may include determining whether the direct current is equal to or greater than the reference current if the direct voltage is below the operating voltage (S1470). The reference current may be a predetermined current. The reference current may be sufficient current intensity to charge the DC link capacitor. In addition, since the voltage difference between the inverter side and the battery side is large, the reference current may be set to a predetermined value or lower because a circuit damage due to an inrush current may occur if the reference current is higher than a predetermined level. The power supply system may stop providing the initial charge current if the DC current is equal to or greater than the reference current (S1480). In this case, the DC / DC converter is switched off and no DC current is supplied to the DC link capacitor. Conversely, the power supply system may continue to provide an initial charge current if the direct current is below the reference current.

After discontinuing the provision of the initial charge current, the power supply system may include determining (S1490) whether the direct current is below the set current. The set current may be a preset current. The set current may be less than the reference current. For example, the set current may be 0A. The power supply system may continue to stop providing the initial charge current if the direct current is not below the set current. Conversely, the power supply system can provide an initial charge current when the direct current is below the set current. That is, the power supply system may initial charge the DC link capacitor according to the magnitude of the DC current supplied to the DC link capacitor, thereby stabilizing the initial charge of the DC link capacitor.

FIG. 15 is a view for explaining a power supply method of an energy storage system according to an embodiment, FIG. 17 is a view for explaining a power conversion efficiency control method of a DC / DC converter of an energy storage system according to an embodiment And FIG. 16 is a diagram for explaining a configuration of a converter efficiency control unit applied to an energy storage system of a power supply system according to an embodiment.

Referring to FIG. 15, a power supply method according to an embodiment may include a step S1510 in which the energy storage system operates in a charge mode or a discharge mode.

The power supply method may include determining whether the power efficiency is in a converter efficiency control region (S1520). That is, the energy storage system may determine whether it is necessary to control the power conversion efficiency of the DC / DC converter. In this case, the energy storage system can determine that the output power is less than the reference power (S1530). The output power may be the current output of the DC / DC converter. The reference power may be an output power at which the power conversion efficiency of the DC / DC converter becomes a predetermined efficiency. The reference power can be set in advance. For example, the reference power may be a power that is a predetermined ratio of the maximum output power of the DC / DC converter. For example, the reference power may be 25% power at the maximum output power of the DC / DC converter.

If the output power is not less than the reference power, the charging operation or the discharging operation can be performed without converter efficiency control (S1550).

If the output power is less than the reference power, the energy storage system may include a step S1540 of performing converter efficiency control.

More specifically, referring to Fig. 17, the converter efficiency control may include calculating the pulse width based on the output power (S1541). More specifically, the pulse width calculation can use Equation (1).

(Equation 1)

For example, the converter efficiency can be controlled up to 25% of the output power of a DC / DC converter having a maximum output power of 5 kW, and the pulse width of 1 kW can be calculated by setting the repetition period of the PWM signal to 2 ms. In this case, the pulse width of 1 kW may be 1.6 ms, which is 1 kW / (5 kW * 25%) * 2 ms.

In addition, the converter efficiency control can determine the average power value (S1542). The average power value can be calculated by measuring the output power value during a predetermined number of repetition cycles of the PWM signal by the charge control section. Thereafter, the converter efficiency control can calculate a comparison value between the output power and the average power value (S1543). That is, the comparison value may be a value obtained by subtracting the average power value from the output power. For example, referring to FIG. 16, the energy storage system 20 may include a converter efficiency controller 500. The converter efficiency control unit 500 may be included in the charge control unit 300, but is not limited thereto. The converter efficiency control unit 500 can calculate the power difference value Pd by comparing the output power Pdc with the average power value Pavg. Thereafter, the converter efficiency control can calculate the power compensation value based on the comparison value (S1544). For example, the converter efficiency control unit 500 may include a compensation unit 510. The compensation unit 510 may be a PI controller. The compensation unit 510 may provide the input power difference value Pd as the power compensation value Pc. Thereafter, the converter efficiency control may provide the compensated output power by compensating the power compensation value to the reference power (S1545). For example, the converter efficiency controller 500 may provide the compensated output power Pdc * by adding the power compensation value Pc to the reference power Pref. In this case, the pulse width calculation in S1541 can be calculated based on the compensated output power.

18 is a view for explaining an energy storage system according to another embodiment.

Referring to FIG. 18, the energy storage system 20 according to another embodiment may include a DC / DC converter 1800, a battery 200, and a charge controller 300. Although not shown in FIG. 1, the energy storage system 20 may be coupled to the inverter 30 via a DC link capacitor 90. That is, the DC link capacitor 90 may be disposed between the energy storage system 20 and the inverter 30. [ The energy storage system 20 may receive the DC voltage Vdc of the DC link capacitor 90 in the charge mode and provide the DC voltage Vdc to the DC link capacitor 90 in the discharge mode. In addition, the configuration included in the DC / DC converter of the energy storage system according to another embodiment to be described later may be included in the configuration of the DC / DC converter of the energy storage system according to the embodiment of FIGS. The battery 200 receives the charging power from the DC / DC converter 1800 in the charging mode, and can perform the charging operation by the received power. Also, the battery 200 can output the stored power to the DC / DC converter 1800 in the discharge mode. In addition, the battery 200 may include a plurality of battery cells for performing the charging operation and the discharging operation. Also, the battery 200 may be connected to the second stage Nb.

The charge control unit 300 may include a battery management system (BMS). The charge control unit 300 may provide the system control unit 80 with battery state information on the state of the battery 200. [ For example, the charge control unit 300 monitors at least one of the voltage, current, temperature, remaining power, and charge state of the battery 200, and transmits status information of the monitored battery 200 to the system control unit 80 . In addition, the charge controller 300 may be configured to allow a plurality of battery cells to maintain an appropriate voltage while charging or discharging. Further, the charge control unit 300 can operate based on the control signal of the system control unit 80. [ Also, the charge controller 300 may control the DC / DC converter 1800 according to the status information of the monitored battery 200. Also, the charge controller 300 may control the DC / DC converter 1800 according to the charge mode or the discharge mode. More specifically, the charge control unit 300 provides a charge control signal or a discharge control signal for controlling the DC / DC converter 1800 to the control unit 1830 of the DC / DC converter 1800 and supplies the control signal to the DC / 1800 may provide a PWM signal to the switch of the DC / DC converter 1800 based on the charge control signal or the discharge control signal. Also, the charge controller 300 may be driven based on the second drive power supply VCC2 provided by the sub power supply 1850. [

The DC / DC converter 1800 can convert the magnitude of the DC power supplied by the energy storage system 20 in the charging mode or in the discharging mode. That is, the DC / DC converter 1800 may be a bi-directional DC / DC converter. More specifically, the DC / DC converter 2300 converts the DC power supplied from the power generation device 10 or the inverter 30 to the DC link capacitor 90 into a voltage magnitude for charging the battery 200, 200). Also, the DC / DC converter 1800 may convert the DC voltage provided by the battery 200 into a voltage magnitude that the inverter 30 can utilize and provide the DC voltage to the DC link capacitor 90.

The DC / DC converter 1800 may include an overcurrent protection circuit portion 1810, a bridge circuit portion 1820, a control portion 1830, a DC stabilization circuit portion 1840, an auxiliary power portion 1850, and a backup power portion 1860.

The control unit 1830 may generate a PWM signal based on the control signal provided from the charge control unit 300 and provide the generated PWM signal to the bridge circuit unit 1820 including the switch. The controller 1830 may be driven based on the first driving power VCC1 provided by the auxiliary power unit 1850. [

The overcurrent protection circuit portion 1810 can prevent EOS or overcurrent flowing into the energy storage system 20 or flowing out to the outside. The overcurrent protection circuit portion 1810 may be disposed between the bridge circuit portion 1820 and the first end Na connected to the DC link capacitor 90. In addition, the overcurrent protection circuit portion 1810 may include a circuit breaker. In this case, the overcurrent protection circuit portion 1810 may open between the first stage Na and the bridge circuit portion 1820 when EOS or an overcurrent flows into the energy storage system 20. Thus, the overcurrent protection circuit portion 1810 can block the input / output of the current to / from the energy storage system 20.

The bridge circuit portion 1820 may be disposed between the overcurrent protection circuit portion 1810 and the DC stabilization circuit portion 1840 and may be electrically connected to each configuration. The bridge circuit unit 1820 can drop the DC voltage of the DC power input from the overcurrent protection circuit unit 1810 in the step-down mode and output it to the DC stabilization circuit unit 1840. Further, the bridge circuit portion 1820 can output the DC voltage of the DC power inputted from the DC stabilization circuit portion 1840 in the step-up mode to the overcurrent protection circuit portion 1810 by increasing the voltage. The bridge circuit portion 1820 may include one or more switches. For example, the bridge circuit portion 1820 may be an isolated full bridge circuit of FIG. As another example, the bridge circuit portion 1820 may be the non-isolated full bridge circuit of FIG. The present invention is not limited thereto and the bridge circuit portion 1820 may be configured as a half bridge circuit. The bridge circuit portion 1820 can operate based on the PWM signal of the control portion 1830. [

The DC stabilization circuit portion 1840 can operate such that the DC voltage increases in the step-up mode of the bridge circuit portion 1820 and the DC voltage decreases in the step-down mode. Further, the DC stabilization circuit portion 1840 may be an LC filter. The DC stabilization circuit portion 1840 may be connected to the second stage Nb.

The auxiliary power supply 1850 can generate the driving power based on the first power P1 provided in the second stage Nb. The first power P1 provided in the second stage Nb is based on the energy stored in the battery 200. [ The first power P1 may be standby power. The auxiliary power supply 1850 receives the second power P2 from the backup power supply 1860 when the first power P1 is not supplied from the second stage Nb, Thereby generating driving power. For example, when the first power P1 is not supplied from the second stage Nb to the auxiliary power source 1850, the battery 200 connected to the second stage Nb may be overdischarged. The second power P2 may be the minimum power for generating the driving power. The driving power may be plural. The driving power source includes a first driving power source VCC1 provided to the charge control unit 300 of the energy storage system 20 and a second driving power source VCC2 provided to the control unit 1830 of the DC / DC converter 1800 can do. However, the present invention is not limited thereto, and the auxiliary power supply 1860 may output a plurality of driving power sources having different voltage levels as required. More specifically, the auxiliary power unit 1850 may be connected to the output terminal of the backup power unit 1860 and the second stage Nb at the third stage Nc disposed at the input stage. The first power P1 may be input to the third stage Nc and input to the input stage if the first power P1 is provided to the second stage Nb. The auxiliary power supply 1850 may be configured such that when the first power P1 is not provided to the second stage Nb and the second power P2 is provided to the second stage Nb, May be input to the stage Nc and input to the input stage. Therefore, even if the battery is overdriven, the DC / DC converter can generate the driving power and perform the charging operation of the battery. In addition, the DC / DC converter can be charged without battery replacement even when the battery is overdriven.

The backup power source 1860 can provide the second power P2 based on the power provided by the DC link capacitor 90 or the inverter 30. [ More specifically, the backup power source unit 1860 may be electrically connected between the first stage Na and the auxiliary power source unit 1850. The backup power supply unit 1860 may generate the second power P2 based on the third power P3 provided at the first stage Na. The backup power source unit 1860 may provide the second power P2 to the sub power source unit 1850 when the first power P1 is not supplied from the second stage Nb to the sub power source unit 1850. [ For example, the backup power supply unit 1860 may have one end connected to the first end Na and the other end connected to the third end Nc. The backup power source 1860 may provide the second power P2 to the third stage Nc and the second power P2 may provide the auxiliary power source 1850 at the third stage Nc.

Therefore, another embodiment can charge the battery even if the battery is overdischarged. Further, another embodiment does not require replacement of the battery even if the battery is overdischarged.

19 is a view for explaining an energy storage system according to another embodiment.

Referring to FIG. 19, the energy storage system according to another embodiment of FIG. 19 is the same as the remaining configuration except for the current limiter 1870 in the energy storage system of FIG. Therefore, the same description as the energy storage system of Fig. 18 is omitted.

The energy storage system 20 according to another embodiment may include a DC / DC converter 1800 including a current limiter 1870.

The current limiter 1870 may be disposed at the input of the auxiliary power supply 1850. In one example, the current limiting portion 1870 may be disposed in the third stage Nc. The current limiter 1870 can prevent the power input to the auxiliary power supply 1850 from being supplied in the reverse direction. In addition, the current limiter 8170 can be prevented from being provided to the configuration in which the provided power should not be provided. More specifically, the current limiter 1870 may include a first diode D1 and a second diode D2. The first diode D1 allows the first power P1 provided at the second stage Nb to be provided at the third stage Nc. In addition, the first diode D1 may prevent the second power P2 from being supplied to the second stage Nb. The second diode D2 allows the second power P2 provided by the backup power source 1860 to be provided to the third stage Nc. In addition, the second diode D2 may prevent the first power P1 from being supplied to the backup power source 1860. [

Therefore, in the DC / DC converter according to another embodiment, the auxiliary power unit can generate stable driving power by using the current limiting unit, and the charging of the unwanted battery can be prevented.

20 is a view for explaining an energy storage system according to another embodiment.

Referring to FIG. 20, the energy storage system according to another embodiment of FIG. 20 is the same as the energy storage system of FIG. 18 except for the DC / DC converter. Therefore, the same description as the energy storage system of Fig. 18 is omitted.

The DC / DC converter 2000 may include an overcurrent protection circuit unit 2010, a bridge circuit unit 2020, a control unit 2030, a DC stabilization circuit unit 2040, an auxiliary power unit 2050, and a backup power source unit 2060. Although not shown, the DC / DC converter 2000 may further include the current limiting unit of FIG.

The control unit 2030 may generate a PWM signal based on the control signal provided from the charge control unit 300 and provide the generated PWM signal to the bridge circuit unit 2020 including the switch. In addition, the controller 2030 can be driven based on the first driving power VCC1 provided by the auxiliary power unit 2050. [

The overcurrent protection circuit 2010 can prevent EOS or overcurrent flowing into the energy storage system 20 or flowing out to the outside. The overcurrent protection circuit 2010 may be disposed between the first stage Na connected to the DC link capacitor 90 and the bridge circuit 2020. In addition, the overcurrent protection circuit 2010 may include a circuit breaker. In this case, the overcurrent protection circuit 2010 may open between the first stage Na and the bridge circuit 2020 when EOS or an overcurrent flows into the energy storage system 20. Therefore, the overcurrent protection circuit 2010 can block the input / output of the current to / from the energy storage system 20.

The bridge circuit unit 2020 may be disposed between the overcurrent protection circuit unit 2010 and the DC stabilization circuit unit 2040 and may be electrically connected to each configuration. The bridge circuit unit 2020 can drop the DC voltage of the DC power input from the overcurrent protection circuit unit 2010 in the step down mode and output it to the DC stabilization circuit unit 2040. Further, the bridge circuit unit 2020 can output the DC voltage of the DC power inputted from the DC stabilization circuit unit 2040 in the step-up mode to the overcurrent protection circuit 2010 by increasing the voltage. Bridge circuitry 2020 may include one or more switches. As an example, the bridge circuit portion 2020 may be an isolated full bridge circuit of FIG. As another example, the bridge circuit portion 2020 may be the non-isolated full bridge circuit of FIG. However, the present invention is not limited to this, and the bridge circuit portion 2020 may be constituted by a half bridge circuit. The bridge circuit section 2020 can operate based on the PWM signal of the control section 2030. [

The DC stabilization circuit portion 2040 can operate such that the DC voltage increases in the step-up mode of the bridge circuit portion 2020 and the DC voltage decreases in the step-down mode. Further, the DC stabilization circuit portion 2040 may be an LC filter. The DC stabilization circuit portion 2040 may be connected to the second stage Nb.

The auxiliary power supply unit 2050 can generate the driving power based on the first power P1 provided in the second stage Nb. The first power P1 provided in the second stage Nb is based on the energy stored in the battery 200. [ The first power P1 may be standby power. The auxiliary power source unit 2050 receives the second power P2 from the backup power source unit 2060 when the first power P1 is not supplied from the second stage Nb, Thereby generating driving power. For example, when the first power P1 is not supplied from the second stage Nb to the auxiliary power source unit 2050, the battery 200 connected to the second stage Nb may be overdischarged. The second power P2 may be the minimum power for generating the driving power. The driving power may be plural. The driving power source includes a first driving power source VCC1 provided to the charge control unit 300 of the energy storage system 20 and a second driving power source VCC2 provided to the control unit 2030 of the DC / can do. However, the present invention is not limited thereto, and the auxiliary power supply unit 2060 may output a plurality of driving power supplies having different voltage levels as required. More specifically, the auxiliary power unit 2050 may be connected to the output terminal of the backup power unit 2060 and the second stage Nb at the third stage Nc disposed at the input stage. The first power P1 may be input to the third stage Nc and input to the input unit if the first power P1 is provided to the second stage Nb. When the first power P1 is not provided to the second stage Nb and the second power P2 is provided to the second stage Nb, the second power P1 is supplied to the third stage Nb, May be input to the input unit in the stage Nc. Therefore, even if the battery is overdriven, the DC / DC converter can generate the driving power and perform the charging operation of the battery. In addition, the DC / DC converter can be charged without battery replacement even when the battery is overdriven.

The backup power source 2060 may provide the second power P2 based on the power provided from an external power source disposed outside the DC / DC converter 2000. [ More specifically, the backup power supply unit 1860 may be electrically connected between the external input terminal Input E and the auxiliary power supply unit 2050. The backup power source unit 2060 may generate the second power P2 based on the fourth power P4 provided from the external input terminal InputE. The backup power source unit 2060 may provide the second power P 2 to the sub power source unit 2050 when the first power P 1 is not supplied from the second stage Nb to the sub power source unit 1850. For example, one end of the backup power source 2060 may be connected to the external input terminal inputE and the other end may be connected to the third end Nc. The backup power source unit 2060 may provide the second power P2 to the third stage Nc and the second power source P2 may provide the auxiliary power source unit 2050 at the third stage Nc.

Therefore, another embodiment can charge the battery even if the battery is overdischarged. Further, another embodiment does not require replacement of the battery even if the battery is overdischarged.

FIG. 21 is a view for explaining an energy storage system according to another embodiment.

Referring to FIG. 21, the energy storage system according to another embodiment of FIG. 21 has the same configuration except for the backup power supply unit and the backup power supply control unit in the energy storage systems of FIGS. 18 and 20. FIG. Therefore, the same description as the energy storage system of Figs. 18 and 20 is omitted.

The backup power source unit 2060 may provide the second power P2 based on the power provided from the backup power source control unit 2070. [ More specifically, the backup power source unit 1860 may be electrically connected between the backup power source control unit 2070 and the auxiliary power source unit 2050. The backup power source unit 2060 may generate the second power P2 based on the fifth power P5 provided from the backup power source control unit 2070. [ The backup power source unit 2060 may provide the second power P 2 to the sub power source unit 2050 when the first power P 1 is not supplied from the second stage Nb to the sub power source unit 1850. For example, one end of the backup power source unit 2060 may be connected to the backup power source control unit 2070, and the other end may be connected to the third end Nc. The backup power source unit 2060 may provide the second power P2 to the third stage Nc and the second power source P2 may provide the auxiliary power source unit 2050 at the third stage Nc.

The DC / DC converter of the energy storage system according to another embodiment may include a backup power controller 2070. The backup power control unit 2070 selects one of power supplied from the external power source and power supplied from the first stage Na based on the control signal of the controller 2030 and supplies the power to the backup power source unit 2060 . More specifically, the backup power source control unit 2070 may be disposed between the external input terminal InputE, the first stage Na, and the backup power source unit 2060. The backup power control unit 2070 may include a switch. For example, the control unit 2030 may control the backup power control unit 2070 to provide the backup power unit 2060 with the third power P3 of the first stage Na as the fifth power P5. The control unit 2030 may control the backup power control unit 2070 to provide the backup power unit 2060 with the fourth power P4 of the external input terminal InputE as the fifth power P5. Therefore, another embodiment can charge the battery even if the battery is overdischarged. Further, another embodiment does not require replacement of the battery even if the battery is overdischarged.

22 is a diagram for explaining a power conversion method for charging a battery in a DC / DC converter of an energy storage system according to an embodiment.

The power conversion method of FIG. 22 can use the configuration of the DC / DC converter of FIG. 18 to FIG.

Referring to FIG. 22, the power conversion method of the DC / DC converter according to the embodiment may include determining whether the first power is provided in the second stage (S2201). For example, in the battery discharge state, the auxiliary power unit can determine whether the first power is supplied in the first stage.

The power conversion method of the DC / DC converter according to the embodiment may include the step S2202 of providing the first power when the first power is supplied to the auxiliary power unit in the second stage. That is, when the first power is supplied in the first stage, the sub power source can receive the first power.

The power conversion method of the DC / DC converter according to the embodiment may include a step S2203 of generating the driving power of the control unit based on the first power when the first power is supplied. More specifically, the sub power supply unit can generate a plurality of driving power supplies based on the first power. The auxiliary power supply can provide the generated drive power to the required configuration. For example, as illustrated in FIGS. 18 to 21, the auxiliary power unit may generate a first driving power for driving the charge control unit and a second driving power for driving the control unit of the DC / DC converter.

The power conversion method of the DC / DC converter according to the embodiment may include a step S2204 in which the backup power source supplies the second power to the sub power source if the first power is not supplied in the second stage in S2201. A method in which the backup power supply unit supplies the second power to the auxiliary power supply unit may be the same as the configuration in which the backup power supply unit of FIGS. 18 to 21 provides the second power supply to the auxiliary power supply unit.

The power conversion method of the DC / DC converter according to the embodiment may include the step S2205 of generating the driving power of the control unit based on the second power. More specifically, the sub power supply unit can generate a plurality of driving power supplies based on the second power. The auxiliary power supply can provide the generated drive power to the required configuration. For example, as illustrated in FIGS. 18 to 21, the auxiliary power unit may generate a first driving power for driving the charge control unit and a second driving power for driving the control unit of the DC / DC converter.

Therefore, another embodiment can charge the battery even if the battery is overdischarged. Further, another embodiment does not require replacement of the battery even if the battery is overdischarged.

23 is a view for explaining an energy storage system according to another embodiment.

Referring to FIG. 23, the energy storage system 20 according to another embodiment may include a DC / DC converter 2300, a battery 200, and a charge controller 300. Although not shown in FIG. 1, the energy storage system 20 may be coupled to the inverter 30 via a DC link capacitor 90. That is, the DC link capacitor 90 may be disposed between the energy storage system 20 and the inverter 30. [ The energy storage system 20 may receive the DC voltage Vdc of the DC link capacitor 90 in the charge mode and provide the DC voltage Vdc to the DC link capacitor 90 in the discharge mode. In addition, the configuration included in the DC / DC converter of the energy storage system according to another embodiment to be described later may be included in the configuration of the DC / DC converter of the energy storage system according to the embodiment of FIG. 2 to FIG. The battery 200 receives the charging power from the DC / DC converter 2300 in the charging mode, and can perform the charging operation by the received power. Also, the battery 200 may output the stored power to the DC / DC converter 2300 in the discharge mode. In addition, the battery 200 may include a plurality of battery cells for performing the charging operation and the discharging operation. Also, the battery 200 may be connected to the second stage Nb.

The charge control unit 300 may include a battery management system (BMS). The charge control unit 300 may provide the system control unit 80 with battery state information on the state of the battery 200. [ For example, the charge control unit 300 monitors at least one of the voltage, current, temperature, remaining power, and charge state of the battery 200, and transmits status information of the monitored battery 200 to the system control unit 80 . In addition, the charge controller 300 may be configured to allow a plurality of battery cells to maintain an appropriate voltage while charging or discharging. Further, the charge control unit 300 can operate based on the control signal of the system control unit 80. [ Also, the charge controller 300 may control the DC / DC converter 2300 according to the status information of the monitored battery 200. Also, the charge controller 300 may control the DC / DC converter 2300 according to the charge mode or the discharge mode. More specifically, the charge control unit 300 provides a charge control signal or a discharge control signal for controlling the DC / DC converter 2300 to the control unit 2330 of the DC / DC converter 2300 and supplies the control signal to the DC / 2300 may provide a PWM signal to the switch of the DC / DC converter 2300 based on the charge control signal or the discharge control signal.

The DC / DC converter 2300 can convert the magnitude of the DC power supplied by the energy storage system 20 in the charging mode or in the discharging mode. That is, the DC / DC converter 2300 may be a bi-directional DC / DC converter. More specifically, the DC / DC converter 2300 converts the DC power supplied from the power generation device 10 or the inverter 30 to the DC link capacitor 90 into a voltage magnitude for charging the battery 200, 200). Also, the DC / DC converter 2300 may convert the DC voltage provided by the battery 200 into a voltage magnitude that the inverter 30 can use to provide the DC voltage to the DC link capacitor 90. Also, the DC / DC converter 2300 can operate in the charge mode, the standby mode, and the discharge mode based on the voltage provided by the DC voltage link capacitor. That is, the DC / DC converter 2300 can monitor the voltage supplied from the DC voltage link capacitor to determine whether to operate the charging mode, the standby mode, and the discharge mode, and to operate the DC / have. A more detailed description of the operation of the DC / DC converter 2300 in the charging mode, the standby mode, and the discharging mode will be described later.

The DC / DC converter 2300 may include an overcurrent protection circuit portion 2310, a bridge circuit portion 2320, a control portion 2330, a DC stabilization circuit portion 2340, an auxiliary power portion 2350, and a backup power portion 2360.

The control unit 2330 can control the bridge circuit unit 2320. For example, the control unit 2330 may generate a PWM signal based on the control signal provided from the charge control unit 300 and provide the generated PWM signal to the bridge circuit unit 2320 including the switch. As another example, the control unit 2330 may determine the operating mode and the reference power according to the magnitude of the voltage provided in the DC link capacitor 90. [ Further, the control unit 2330 may generate a PWM signal based on the determined reference power and provide it to the bridge circuit unit 2320 including the switch. A specific description of another example will be described later.

The overcurrent protection circuit portion 2310 can prevent EOS or overcurrent flowing into the energy storage system 20 or flowing out to the outside. The overcurrent protection circuit portion 2310 may be disposed between the first stage Na connected to the DC link capacitor 90 and the bridge circuit portion 2320. In addition, the overcurrent protection circuit portion 2310 may include a circuit breaker. In this case, the overcurrent protection circuit portion 2310 may open between the first stage Na and the bridge circuit portion 2320 when EOS or an overcurrent flows into the energy storage system 20. Therefore, the overcurrent protection circuit portion 2310 can block the input / output of the current to / from the energy storage system 20.

The bridge circuit unit 2320 may be disposed between the overcurrent protection circuit unit 2310 and the DC stabilization circuit unit 2340 and may be electrically connected to each configuration. The bridge circuit portion 2320 can drop the DC voltage of the DC power input from the overcurrent protection circuit portion 2310 in the step down mode and output it to the DC stabilization circuit portion 2340. Further, the bridge circuit portion 2320 can output the DC voltage of the DC power inputted from the DC stabilization circuit portion 2340 in the step-up mode to the overcurrent protection circuit portion 2310 by increasing the voltage. The bridge circuit portion 2320 may include one or more switches. In one example, the bridge circuit portion 2320 may be an isolated full bridge circuit of FIG. As another example, the bridge circuit portion 2320 may be the non-isolated full bridge circuit of FIG. The present invention is not limited thereto and the bridge circuit portion 2320 may be configured as a half bridge circuit. The bridge circuit portion 2320 can operate based on the PWM signal of the control portion 2330. [

The DC stabilization circuit unit 2340 can operate such that the DC voltage rises in the step-up mode of the bridge circuit unit 2320 and the DC voltage falls in the step-down mode. In addition, the DC stabilization circuit portion 2340 may be an LC filter. The DC stabilization circuit portion 2340 may be connected to the second stage Nb.

The sensing unit 2350 may sense the voltage of the first stage Na and provide the sensed voltage to the control unit 2330. [ The voltage of the first stage (Na) may be the DC voltage provided by the DC link capacitor (90). Also, the sensing unit 2350 can be controlled by the control unit 2330.

Therefore, another embodiment can quickly determine the operation mode of the charging or discharging of the battery. Further, another embodiment does not require a separate communication line and a communication unit for controlling the droop in charging or discharging the battery. Still another embodiment is capable of rapid droop control upon battery charging or discharging.

FIG. 24 is a view for explaining the control unit of FIG. 23, FIG. 25 is a diagram for explaining a droop control curve of the energy storage system of FIG. 23, FIG. 26 is a view for explaining the reference current determination unit of FIG. 24, 27 is a view for explaining the current control unit of Fig.

Referring to FIG. 24, the control unit 2330 of the DC / DC converter 2300 according to another embodiment may include a reference power determination unit 2331. The reference power determination unit 2331 can determine the operation mode and the reference power.

For example, the reference power determination unit 2331 can determine the operation mode and the reference power according to the magnitude of the voltage of the first stage. More specifically, referring to FIG. 25, the reference power determination unit 2331 can determine the operation mode and the reference power based on the droop control curve according to the voltage of the first stage. In the operation mode, the reference power determination unit 2331 can determine the charging mode if the voltage Vdc of the first stage is equal to or higher than the first voltage V1. The reference power determination unit 2331 can determine the standby mode if the voltage Vdc of the first stage is smaller than the first voltage V1 and is greater than the second voltage V2. The reference power determination unit 2331 can determine the discharge mode if the voltage Vdc of the first stage is equal to or less than the second voltage V2. The first voltage V1 and the second voltage V2 may be a predetermined voltage and the first voltage V1 and the second voltage V2 may be set by using an external communication or directly by a user . The first voltage V1 may be greater than the second voltage V2. In the case of the reference power, the reference power determination unit 2331 subtracts the first voltage V1 from the voltage Vdc of the first stage in the operation mode, and then calculates the reference power by multiplying the charge power gradient Sc by . The reference power determination unit 2331 may calculate the reference power by subtracting the voltage Vdc of the first stage from the second voltage V2 and multiplying the discharge power slope Sd by the reference voltage Sd when the operation mode is the discharge mode. The charge power slope Sc and the discharge power slope Sd may be predetermined values, but are not limited thereto, and may be set by an external communication or directly by a user. The charge power slope Sc and the discharge power slope Sd may be different from each other, but are not limited thereto and may be equal to each other. In addition, the droop control curve may limit the reference power to maximum power, including maximum power. Specifically, the maximum power may include a maximum charging power PCMax and a maximum discharge power PDMax. The maximum charge power PCMax may be a power value at which the reference power can be the maximum in the operation mode of the charge mode. The maximum discharge power PDMax may be a power value at which the reference power can be maximized in the operation mode in the discharge mode.

As another example, the reference power determination unit 2331 can determine the operation mode according to the battery voltage state. More specifically, the reference power determination unit 2331 can operate in the charge mode if the battery voltage is equal to or higher than a predetermined voltage.

As another example, the reference power determination unit 2331 may determine the operation mode and the reference power according to the user's control. In this case, the user can determine the operation mode and the reference power directly or via communication.

Also, the reference power determination unit 2331 can determine an operation mode and a reference power by selecting one of the examples, another example, and another example.

The controller 2330 of the DC / DC converter 2300 according to another embodiment may include a reference current determiner 2332. The reference current determination unit 2332 can determine the reference current based on the operation mode and the reference power determined by the reference power determination unit 2331. [ More specifically, referring to FIG. 26, in the charging mode (a), the reference current determination unit 2332 may include a first reference current selection unit 2604. The first reference current selection unit 2604 selects the reference current I_CCR determined using the droop curve according to the magnitude of the first stage voltage determined by the reference power determination unit 2331, And the reference current I_BR determined according to the battery voltage state as the reference current I_CR for generating the PWM signal as the switching signal. In the case of the charging mode (a), the reference current determination unit 2332 may include a first current extraction unit 2601. The first current extractor 2601 divides the reference power P_CCR determined using the droop curve according to the magnitude of the voltage of the first stage determined by the reference power determiner 2331 by the battery voltage V_B to obtain a reference current I_CCR Can be extracted. Also, in the charging mode (a), the reference current determination unit 2332 may include a first comparison unit 2602 and a PI voltage controller 2603. The first comparing unit 2602 may compare the battery voltage V_B with a preset battery reference voltage V_BR and provide the battery voltage difference value V_Bd to the PI voltage controller 2603. [ The PI voltage controller 2603 can provide the reference current I_BR according to the PI control based on the battery voltage difference value V_Bd. In the discharge mode (b), the reference current determination unit 2332 may include a second reference current selection unit 2604. The second reference current selection unit 2604 selects the reference current I_CDR determined using the droop curve and the reference current I_MDR determined according to the user's setting according to the magnitude of the voltage of the first stage determined by the reference power determination unit 2331, ) Can be selected as the reference current (I_DR) for generating the PWM signal, which is the switching signal. In the discharge mode (b), the reference current determination unit 2332 may include a second current extraction unit 2605. The second current extraction unit 2605 divides the reference power P_CDR determined using the droop curve according to the magnitude of the voltage of the first stage determined by the reference power determination unit 2331 by the voltage V_L of the first stage, The current I_CDR can be extracted.

The control unit 2330 of the DC / DC converter 2300 according to another embodiment may include a limited power determination unit 2333. The limiting power determination unit 2333 may limit the reference power such that the reference power does not exceed the predetermined power. More specifically, the limiting power determination unit 2333 may cause the maximum power to be provided to the current control unit 2334 as the reference power if the determined reference power is greater than the set maximum power. The limiting power determination unit 2333 can also cause the inverter limit power to be provided to the current control unit 2334 as the reference power if the determined reference power is greater than the inverter limit power according to the inverter 30. [ If the determined reference power is greater than the battery limitation power according to the battery 200, the limited power determination unit 2333 may provide the battery limited power to the current control unit 2334 with the reference power.

The control unit 2330 of the DC / DC converter 2300 according to another embodiment may include a current control unit 2334. The current control section 2334 can generate the PWM signal which is the switching signal based on the determined reference current. 27, in the charging mode (a), the current controller 2334 includes a second comparator 2701, a first PI current controller 2702, and a first PWM converter 2703 . The second comparator 2701 may compare the reference current I_CR with the battery current I_B input to the battery 200 and provide the reference current difference value I_CRD to the first PI current controller 2702 . The first PI current controller 2702 may provide the first PWM converter 2703 with the charge control current I_CC according to the PI control based on the reference current difference value I_CRD. The first PWM converter 2703 can provide the PWM signal as a switching signal to the bridge circuit unit 2320 based on the charge control current I_CC. In the discharge mode (b), the current controller 2334 may include a third comparator 2704, a second PI current controller 2705, and a second PWM converter 2706. The third comparator 2704 compares the reference current I_DR with the current I_L of the first stage Na input to the battery 200 and outputs the reference current difference value I_DRD to the second PI current controller 2705 ). The second PI current controller 2705 may provide the second PWM converter 2706 with the discharge control current I_DC according to the PI control based on the reference current difference value I_DRD. The second PWM converter 2706 can provide the PWM signal as a switching signal to the bridge circuit unit 2320 based on the discharge control current I_DC.

FIG. 28 is a diagram for explaining a power conversion method of the energy storage system of FIG. 23. FIG.

Referring to FIG. 28, the power conversion method of the energy storage system may include sensing the voltage of the first stage (S2810). The first stage may refer to a node to which a DC / DC converter and a DC link capacitor are connected. The method of sensing the voltage of the first stage may follow the description of Fig.

The power conversion method of the energy storage system may include a step S2820 of selecting the operation mode according to the magnitude of the voltage of the first stage. The operation mode may be any one of a charge mode standby mode and a discharge mode. A detailed description of S2820 is given in Fig.

The power conversion method of the energy storage system may include a step S2830 of determining the reference power according to the magnitude of the voltage of the first stage. The method of determining the reference power according to the magnitude of the voltage of the first stage may follow the description of Figs. 23 to 27 and the description of Fig.

The power conversion method of the energy storage system may include generating a switching signal based on the determined reference power (S2840). The switching signal can control the switching operation of the bridge circuit portion operating in the charging mode or the discharging mode. The method of generating the switching signal based on the determined reference power may follow the description of Figs. 23-27.

FIG. 29 is a diagram for explaining a method of selecting the operation mode of FIG. 28; FIG.

Referring to FIG. 29, a method of selecting an operation mode may include determining whether a voltage of the first stage is higher than a first voltage (S2821). And selecting the charging mode when the voltage of the first stage is higher than the first voltage (S2822).

The method of selecting the operation mode may include determining whether the voltage of the first stage is a second voltage transition if the voltage of the first stage is not equal to or higher than the first voltage (S2823). And selecting the discharge mode if the voltage of the second stage is not higher than the second voltage (S2824). If the voltage of the second stage is not equal to or lower than the second voltage, the process may return to S2821.

FIG. 30 is a diagram for explaining a method of determining the reference power in FIG.

Referring to FIG. 30, a method of determining the reference power may include calculating a first reference power using a voltage of the first stage (S2831). The method of calculating the first reference power using the voltage of the first stage may follow the description of FIG. 23 to FIG.

The method of determining the reference power may include determining whether the first reference power exceeds the maximum power (S2832). If the first reference power exceeds the maximum power, the reference power can be determined as the maximum power (S2833).

The method of determining the reference power may include determining whether the first reference power exceeds the inverter limit power if the first reference power does not exceed the maximum power (S2834). If the first reference power exceeds the inverter limit power, the reference power can be determined as the inverter limit power (S2835).

The method for determining the reference power may include determining whether the first reference power exceeds the battery limit power if the first reference power does not exceed the inverter limit power (S2836). If the first reference power exceeds the battery limit power, the reference power may be determined as the battery limit power (S2837).

The method of determining the reference power may include determining (S2838) the reference power as the first reference power if the first reference power does not exceed the battery limit power.

Therefore, the embodiment can quickly determine the operation mode of the charging or discharging of the battery. In addition, the embodiment does not require a separate communication line and a communication unit for controlling charging or discharging of the battery. According to an embodiment of the present invention, the above-described method can be implemented as a code that can be read by a processor on a medium on which a program is recorded. Examples of the medium that can be read by the processor include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage system, etc. and may be implemented in the form of a carrier wave (for example, transmission over the Internet) .

The embodiments described above are not limited to the configurations and methods described above, but the embodiments may be configured by selectively combining all or a part of the embodiments so that various modifications can be made.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention.

Claims (10)

An overcurrent protection circuit connected to the first end; A DC stabilization circuit portion connected to the second stage; A bridge circuit part electrically connected between the overcurrent protection circuit part and the DC stabilization circuit part and including a switch; And And a control unit for controlling the bridge circuit unit, Wherein the controller determines the operation mode and the reference power according to the magnitude of the voltage of the first stage. The method according to claim 1, Wherein the control unit provides a switching signal to the bridge circuit to control the switch based on the determined reference power. The method according to claim 1, And a DC link capacitor is connected to the first end of the DC / DC converter. The method according to claim 1, The operation mode includes: And a charge mode when the voltage of the first stage is higher than the first voltage, A standby mode when the voltage of the first stage is lower than the first voltage and higher than the second voltage, DC converter according to claim 1 or 2, wherein when the voltage of the first stage is equal to or lower than the second voltage, the DC / DC converter is in a discharge mode. 5. The method of claim 4, The reference power, If the operation mode is the charge mode, subtracting the first voltage from the voltage of the first stage and multiplying the voltage by the charge power slope, And wherein the DC / DC converter is calculated by subtracting the voltage of the first stage from the second voltage and then multiplying by the discharge power slope if the operation mode is the discharge mode. 3. The method of claim 2, Wherein, Generating the switching signal based on the maximum power if the determined reference power is greater than the set maximum power, Generating the switching signal based on the inverter limit power if the determined reference power is greater than the inverter limit power, And the switching signal is generated based on the battery limit power when the determined reference power is greater than the battery limit power. Sensing a voltage of the first stage; Selecting an operation mode according to the magnitude of the voltage of the first stage; Determining a reference power according to the magnitude of the voltage of the first stage; And And generating a switching signal based on the determined reference power, Wherein the switching signal comprises: A signal for controlling a switch constituting a bridge circuit based on the determined reference power, Wherein the voltage of the first stage The voltage of the DC link capacitor Power conversion method. 8. The method of claim 7,  The operation mode includes: And a charge mode when the voltage of the first stage is higher than the first voltage, A standby mode when the voltage of the first stage is lower than the first voltage and higher than the second voltage, If the voltage of the first stage is equal to or lower than the second voltage, Power conversion method. 9. The method of claim 8, The reference power, If the operation mode is the charge mode, subtracting the first voltage from the voltage of the first stage and multiplying the voltage by the charge power slope, And subtracting the voltage of the first stage from the second voltage when the operation mode is the discharge mode and multiplying the voltage by the discharge power gradient Power conversion method. 8. The method of claim 7, Wherein the step of generating the switching signal comprises: Generating the switching signal based on the maximum power if the determined reference power is greater than the set maximum power, Generating the switching signal based on the inverter limit power if the determined reference power is greater than the inverter limit power, Generating the switching signal based on the battery limiting power if the determined reference power is greater than the battery limiting power Power conversion method.

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