WO2024177408A1 - Power transmission device - Google Patents

Abstract

A power transmission device according to one embodiment of the present invention comprises: a PV module connection unit which receives power input from a PV module; a battery connection unit which is connected to a battery to output power to the battery or receive power input from the battery; an inverter connection unit which is connected in parallel to the battery connection unit and, when connected to an inverter, outputs power to the inverter; and a control unit which controls the PV module by communicating with the PV module and controls the battery connection unit and the inverter connection unit to output power inputted from the PV module to the battery or the inverter.

Description

Power transmission device

The present invention relates to a power transmission device, and more specifically, to a power transmission device that efficiently transmits power from a solar power generation module to a battery or an inverter.

Solar power generation is an eco-friendly energy generation method that is widely used as a replacement for existing chemical power generation or nuclear power generation. Solar power generation can be either a standalone type where a battery is connected to a converter or a connected type where it is connected to a power grid. In general, standalone generation consists of photovoltaic power generation, storage batteries, and power conversion devices, while a power grid-connected system is connected to a commercial power source so that power can be exchanged with the load grid line.

The maximum power point of a photovoltaic module varies depending on the amount of sunlight, temperature, etc. To operate the solar cell at the maximum power point, an optimizer or module-level power electronics (MLPE) that performs maximum power point tracking (MPPT) control on a module-by-module basis can be used.

When the output of the photovoltaic module is stored in the battery module, it is charged to the battery through two power conversions of the optimizer of the photovoltaic module and the battery DC-DC converter of the battery module. At this time, the optimizer configured in series with the photovoltaic module 1:1 must be controlled to an appropriate DC (400 V level) voltage for battery charging/discharging and the inverter output connected to the load, which complicates the control and causes the problem of battery over-discharge when the solar power generation system is not operated for a long time due to reasons such as user vacation or system failure.

The technical problem to be solved by the present invention is to provide a power transmission device that efficiently transmits power from a solar power generation module to a battery or an inverter and a solar power generation system including the same.

In order to solve the above technical problem, a power transmission device according to an embodiment of the present invention includes a PV module connection part that receives power from a PV module; a battery connection part that is connected to a battery and outputs power to the battery or receives power from the battery; an inverter connection part that outputs power to the inverter when connected to an inverter and is connected in parallel with the battery connection part; and a control part that controls the PV module through communication with the PV module and controls the battery connection part and the inverter connection part to output power received from the PV module to the battery or the inverter.

In addition, it may include a power line communication unit that performs communication with the PV module through a power line electrically connected to the PV module.

Additionally, the PV module includes an optimizer, and the control unit can transmit a control signal to the optimizer through the power line communication unit.

Additionally, the PV module includes a plurality of PV modules, and the plurality of PV modules can be connected in parallel to the PV module connection portion.

Additionally, the PV module includes a plurality of PV modules, and the plurality of PV modules can be connected in series.

Additionally, it may include an abnormality detection unit that detects whether there is an abnormality in the PV module.

Additionally, it may include an RSD section that lowers the voltage of the PV module to a first value or lower when an abnormality in the PV module is detected.

In addition, it may include an input current sensing unit that measures the input current of the power input to the PV module connection unit; an output voltage sensing unit that measures the output voltage of the power output to at least one of the battery connection unit and the inverter connection unit; and an output current sensing unit that measures the output current of the power output to the inverter connection unit.

In addition, it may include a first switching unit that connects to or disconnects from the battery; and an initial charging unit that performs initial charging when connected to the battery.

In addition, it may include a communication unit that performs communication with a battery management device that manages the battery.

In addition, the device may include a second switching unit for connecting or disconnecting the inverter; and a bypass unit for forming a bypass path on the inverter connecting unit when the connection with the inverter connecting unit is disconnected according to the operation of the second switching unit.

Additionally, the inverter connector can be connected in series with an inverter connector of another power transmission device.

In order to solve the above technical problem, a power transmission device according to an embodiment of the present invention comprises: a PV module connection unit connected to an output of a PV module; a power line communication unit connected to the (+) power line of the PV module connection unit and communicating with the PV module; an abnormality detection unit connected to the (-) power line of the PV module connection unit and detecting an abnormality of the PV module; an input current sensing unit measuring current of the (+) power line of the PV module connection unit; a first diode connected to the (+) power line of the PV module connection unit and blocking current to the PV module; a battery connection unit connected to a battery and outputting power to the battery or receiving power from the battery; an inverter connection unit outputting power to the inverter when connected to an inverter and connected in parallel with the battery connection unit; an output current sensing unit measuring an output voltage of a front end of a node to which the battery connection unit and the inverter connection unit are connected; a first switching unit connected to the (+) power line of the battery connection unit and connecting or disconnecting the battery; an output current sensing unit measuring current of the (+) power line of the inverter connection unit; A second switching unit connected to the (-) power line of the inverter connection unit to connect or disconnect the inverter; and a bypass unit connected to the (+) power line and the (-) power line of the inverter connection unit to form a bypass path.

In addition, the PV module connection part may include an RSD unit that is connected between the (+) power line and the (-) power line and lowers the voltage of the PV module to a first value or lower when an abnormality in the PV module is detected.

Additionally, it may include a first capacitor connecting between the (+) power line and the (-) power line at the front end of the node to which the battery connection part and the inverter connection part are connected.

According to embodiments of the present invention, PV-generated power can charge a battery without passing through a PV DC-DC converter and a battery DC-DC converter, thereby increasing the efficiency of charging a battery module from a PV module. In addition, the system can be easily controlled by forming a DC-link voltage with the voltage of the battery, and when the battery fails, the battery can be separated for operation, the battery can be charged even when the system is shut down, and balancing between batteries is also easy.

FIG. 1 is a block diagram of a power transmission device according to one embodiment of the present invention.

Figure 2 illustrates the connection relationship of each component of a power transmission device according to an embodiment of the present invention.

FIG. 3 illustrates an implementation example of a power transmission device according to an embodiment of the present invention.

FIGS. 4 to 9 are drawings for explaining various connection relationships between a power transmission device and other devices according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

However, the technical idea of the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and within the scope of the technical idea of the present invention, one or more of the components among the embodiments can be selectively combined or substituted for use.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention can be interpreted as having a meaning that can be generally understood by a person of ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, can be interpreted in consideration of the contextual meaning of the relevant technology.

Additionally, the terms used in the embodiments of the present invention are for the purpose of describing the embodiments and are not intended to limit the present invention.

In this specification, the singular may also include the plural unless specifically stated otherwise in the phrase, and when it is described as "A and/or at least one (or more) of B, C", it may include one or more of all combinations that can be combined with A, B, C.

In addition, when describing components of embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish the components from other components, and are not intended to limit the nature, order, or sequence of the components.

And, when a component is described as being 'connected', 'coupled', or 'connected' to another component, it may include not only cases where the component is 'connected', 'coupled', or 'connected' directly to the other component, but also cases where the component is 'connected', 'coupled', or 'connected' by another component between the component and the other component.

In addition, when described as being formed or arranged "above" or "below" each component, "above" or "below" includes not only the case where the two components are in direct contact with each other, but also the case where one or more other components are formed or arranged between the two components. In addition, when expressed as "above" or "below", the meaning of the downward direction as well as the upward direction based on one component may be included.

FIG. 1 is a block diagram of a power transmission device according to an embodiment of the present invention. FIG. 2 illustrates a connection relationship of each component of a power transmission device according to an embodiment of the present invention, FIG. 3 illustrates an implementation example of a power transmission device according to an embodiment of the present invention, and FIGS. 4 to 9 are drawings for explaining various connection relationships between a power transmission device according to an embodiment of the present invention and other devices.

A power transmission device (100) according to an embodiment of the present invention is composed of a PV module connection unit (101), a battery connection unit (102), an inverter connection unit (103), and a control unit (104), and may include a power line communication unit (111), an input current sensing unit (112), a reverse current blocking unit (113), an output voltage sensing unit (114), an output current sensing unit (115), a first switching unit (116), a second switching unit (117), a bypass unit (118), an abnormality detection unit (119), an RSD unit (120), a smoothing unit (121), etc.

The power transmission device (100) according to an embodiment of the present invention is a device that enables efficient power transmission between a PV module (210), a battery (220), and an inverter (230), and acts as a hub, and thus can be referred to as an energy hub. In addition, the power transmission device (100) according to an embodiment of the present invention may configure a battery (220) and a battery module, a PV module (210) and a PV module, or an inverter (230) and an inverter module. In addition, the power transmission device (100) according to an embodiment of the present invention may configure a PV-battery module together with a battery (220) and a PV module (210), or a PV-inverter module together with an inverter (230) and a PV module (210). In addition, a solar power generation system may be configured together with the PV module (210), the battery (220), and the inverter (230).

For this purpose, the power transmission device (100) according to an embodiment of the present invention can perform functions such as communication, PV module control, battery cutoff, bypass, battery monitoring, detection of arcs, etc., and RSD functions. Hereinafter, the power transmission device (100) according to an embodiment of the present invention will be described in detail.

The PV module connection part (101) is connected to the PV module (210) and receives power from the PV module (210).

The PV module (210) generates electricity through solar power generation using sunlight. It may include a PV panel (211) and an optimizer (212). The optimizer (212) may perform maximum power point estimation (MPPT) so that the power output from the PV panel (211) becomes maximum power.

The PV panel (211) may include a plurality of cell strings. A solar cell that performs solar power generation may be expressed as a cell string unit in which a plurality of cells are connected in series. A cell string may include at least one cell, and when including a plurality of cells, the plurality of cells may be connected in series. The cell string may be a solar cell string including solar cells. The solar cell string may form a PV panel. The PV panel (211) may also be referred to as a solar panel or a solar power generation panel. Solar cells generate solar power (PV, Photovoltaic) by utilizing the photoelectric effect. The photovoltaic effect is a phenomenon in which electrons are emitted when light of a specific frequency or higher strikes a specific metal material, and a pn junction is formed using a P-type semiconductor and an n-type semiconductor, and current is generated by utilizing electrons generated by the photoelectric effect, thereby generating power. Solar cells are formed using silicon, etc., and may be formed in a wafer shape. Solar cells are located in places where they can receive a lot of sunlight, such as fields, the exterior walls of buildings, and rooftops, and use sunlight to generate electricity. In this case, the solar cells can be formed as BIPV (building-integrated photovoltaics) that are formed as an integral part of the building.

Since the amount of power generated from a single solar cell is insufficient to be used in a load or power system, power of an appropriate amount can be generated by connecting multiple solar cells in series to form a solar cell string instead of a single solar cell. A solar cell string can be a basic unit for generating power. A photovoltaic panel can be formed by forming multiple cell strings, which are basic units, into panels. Solar cells have different voltage-current characteristics depending on the amount of sunlight, temperature, etc., and the maximum power point (MPP) also changes. (Generated power = voltage X current)

The PV module (210) may include a plurality of PV modules. Each PV module includes a PV panel (211) and an optimizer (212), and the plurality of optimizers (212) are respectively connected to the output power of each cell string and may be connected in series or in parallel with each other. The optimizer optimizes the output power of the cell string so that the solar cell operates at the maximum power point (MPP), which is an operating point where the power of the solar cell is maximum under each condition. Here, the optimizer may include module-level power electronics (MLPE). This is called maximum power point tracking (MPPT), and the efficiency of solar power generation can be increased by using maximum power point tracking. In solar power generation, depending on the characteristics of the relationship between current and voltage and the relationship between voltage and power, the maximum power may be the power when it is about 80% of the maximum voltage, not the maximum voltage. Since this maximum power point continues to change depending on the magnitude of the voltage and current generated by the PV panel, it is necessary to continuously find a point where the maximum power point can occur. That is, in order to pursue the maximum power rather than the maximum voltage, the magnitude of the voltage and current can be varied to achieve the maximum power. That is, the voltage can be reduced and the current can be increased in the direction of increasing the power, or the voltage can be increased and the current can be reduced.

The inverter connection part (103) outputs power to the inverter (230) when connected to the inverter (230). At this time, the inverter connection part (103) is connected in parallel with the battery connection part (102). When connected to the inverter (230), power input from the PV module (210) can be output to the inverter (230) through the inverter (230) or the DC-DC converter (240) connected to the inverter (230).

The inverter (230) can supply power output from the inverter connection part (103) to the load or the grid. The inverter (230) can receive DC power output from the inverter connection part (103), convert it into AC power, and supply power to the load or the grid. It can supply AC power to a load that requires AC power, and transmit the surplus power to the grid, i.e., the system. Alternatively, it can receive AC power from the grid, convert it into DC power, and output it to a power transmission device. Here, the inverter (230) can include a DC-AC inverter. A separate power generation device, such as a diesel generator that can generate and supply power when the power supplied to the load is insufficient, can be connected to the inverter (230), and a circuit breaker that can cut off the connection to the grid and an energy meter that measures the power supplied or provided from the grid can also be connected. When the connection to the grid is cut off, the entire system excluding the grid can be switched to independent operation.

The battery connector (102) is connected to the battery (220) to output power to the battery (220) or receive power from the battery (220). Power input from the PV module (210) through the PV module connector (101) is transmitted to the inverter (230) through the inverter connector (103) and can charge and discharge the battery (220) through the battery connector (102). The battery (220) may include a battery management system (BMS) that manages the battery status.

The control unit (104) controls the PV module (210) through communication with the PV module (210), and controls the battery connection unit (102) and the inverter connection unit (103) to output power input from the PV module (210) to the battery (220) or the inverter (230). The control unit (104) measures input current, output voltage, output current, etc., and receives data including status information from the PV module (210), the battery (220), the inverter (230), an external controller, a load, etc., and controls each configuration so that power input from the PV module (210) can be output to the inverter (230) or the battery (220).

It goes without saying that the control unit (104) includes one or more processors and may further include memory, and that the functions of the control unit (104) or other components may be implemented in software or hardware.

In outputting power input from a PV module (210) to an inverter (230) or a battery (220), a power transmission device (100) according to an embodiment of the present invention may include a power line communication unit (111), an input current sensing unit (112), a reverse current blocking unit (113), an output voltage sensing unit (114), an output current sensing unit (115), a first switching unit (116), a second switching unit (117), a bypass unit (118), an abnormality detection unit (119), an RSD unit (120), a smoothing unit (121), etc. Each of the components may be configured as in FIG. 2 as an example.

The power line communication unit (111) can perform communication with the PV module (210) through a power line electrically connected to the PV module (210). The PV module connection unit (101) can include a (+) power line (122) and a (-) power line (123), and the power line communication unit (111) can perform communication with the PV module (210) by being connected to the (+) power line (122) of the PV module connection unit (101). At this time, the power line communication unit (111) can perform PLC (Power Line Communication) that performs communication using the power line. Alternatively, communication can be performed through wired communication or wireless communication other than the PV module (210). The control unit (104) controls the power line communication unit (111) to perform communication with the PV module (210) through PLC communication to receive information of the PV module (210) or control power of the PV module (210). At this time, the power line communication unit (111) can communicate with the optimizer (212) of the PV module (210). The control unit (104) can control the power output from the PV module (210) by transmitting a control signal to the optimizer (212) through the power line communication unit (111). Control can be performed by transmitting a signal for turning the optimizer (212) on and off or a signal for controlling the output amount of power.

The PV module (210) may include a plurality of PV modules, and the plurality of PV modules may be connected in parallel to the PV module connection portion. The plurality of PV modules (210) may be connected in parallel, as shown in FIG. 4. Alternatively, the plurality of PV modules may be connected in series, as shown in FIG. 6.

When charging a battery (220) by supplying power from a plurality of PV modules (210), if the voltage of the battery is low, the battery (220) can be sufficiently charged with one PV module, and thus the plurality of PV modules (210) can be connected in parallel. Since the plurality of PV modules (210) are connected in parallel, the battery (220) can be sufficiently charged even if a problem occurs in some of the plurality of PV modules (210). If the voltage of the battery is high, it may be difficult to charge the battery with the voltage of one PV module (210). In this case, the PV modules can be connected in series to form a large size of the voltage input to the PV module connection part (101). That is, depending on the voltage of the applied battery, the plurality of PV modules can be connected in parallel or in series.

The abnormality detection unit (119) can detect whether there is an abnormality in the PV module (210). It can detect an arc, etc., that may affect the PV module (210). Here, the arc is a gas insulation breakdown phenomenon that generates current through a non-conductive medium such as air, and when an arc occurs, a lot of heat is generated, which poses a risk of fire, etc. The abnormality detection unit (119) can detect the occurrence of an arc, etc., by including an arc sensor, etc. The abnormality detection unit (119) can be connected to the (-) power line (123) of the PV module connection.

The RSD unit (120) can lower the voltage of the PV module (210) to a first value or lower when an abnormality is detected in the PV module (210). When an abnormality is detected in status information received from the PV module (210), or when a risk of fire or the like occurs, or when an RSD operation command is received from the abnormality detection unit (119) or the outside, the RSD unit (120) can perform an RSD (Rapid Shut Down) function to quickly stop the PV module (210). For the RSD operation, a resistor that consumes power and a switch that connects the resistor can be included. By consuming power through the resistor, the voltage of the PV module (210) can be lowered to a first value or lower in a short period of time, thereby ensuring safety. When the RSD function is included in the optimizer (212) of the PV module (210), the RSD unit (120) may not be applied or may be applied as redundancy to the RSD function of the optimizer (212), thereby increasing safety.

In order to monitor the input/output of power, an input current sensing unit (112), an output voltage sensing unit (114), and an output current sensing unit (115) may be included.

The input current sensing unit (112) can measure the input current of the power input to the PV module connection unit. The input current sensing unit (112) is connected to the (+) power line (122) of the PV module connection unit and can measure the input current. The input current sensing unit (112) can be configured as a current sensor, as shown in FIG. 3.

The output voltage sensing unit (114) can measure the output voltage of the power output from at least one of the battery connection unit (102) and the inverter connection unit (103). It can measure the output voltage, which is the voltage at the front end of the node of the battery connection unit (102) and the inverter connection unit (103) that are connected in parallel. The output voltage sensing unit (114) can be configured as a voltage sensor, as shown in FIG. 3. The control unit (104) can calculate the power generation amount of the PV module (210) by using the current measured by the input current sensing unit (112) and the output voltage measured by the output voltage sensing unit (114).

A reverse current blocking unit (113) and a smoothing unit (121) may be included between the input current sensing unit (112) and the output voltage sensing unit (114). The reverse current blocking unit (113) may prevent current from being applied from the battery (220) or the inverter (230) to the PV module (210). Through this, the safety of the PV module (210) may be improved. The reverse current blocking unit (113) may include a first diode, as shown in FIG. 3. By utilizing the characteristics of the diode, current may flow from the PV module connection unit (101) to the battery (220) or the inverter (230), and reverse current flowing in the opposite direction may be blocked. The smoothing unit (121) may play a role in stabilizing power input from the PV module (210). The power generation of the PV module (210) is affected by the external environment, and may not be able to supply stable power to the inverter (230) or the load due to the occurrence of noise, etc. In order to remove such unstable signals or noise, etc., a smoothing unit (121) may be connected. The smoothing unit (121) may include a first capacitor, which is a smoothing capacitor, as shown in FIG. 3.

The output current sensing unit (115) can measure the output current of the power output to the inverter connection unit (103). Even if the output current sensing unit is connected only to the (+) power line (126) of the inverter connection unit among the battery connection unit (102) and the inverter connection unit (103) that are connected in parallel, the output current to the inverter and the output current to the battery can both be calculated using the input current measured by the input current sensing unit (112) and the output current measured by the output current sensing unit (115). The control unit (104) can calculate and monitor the amount of power output to the inverter (230) and the amount of power output to the battery (220). The output current sensing unit (115) can be configured as a current sensor, as shown in FIG. 3.

The first switching unit (116) can be connected to the battery (220) or disconnected from the battery (220). A switching element that can connect or disconnect the battery (220) can be connected to the battery connection unit (102). The first switching unit (116) can be a relay element, or can include a DC relay, a power semiconductor element, or the like. The first switching unit (116) can be connected to the (+) power line (124) of the battery connection unit.

When the first switching unit (116) connects the battery (220), a pre-charge unit may be included to prevent inrush current, etc. Before connecting the battery (220), the voltage of the battery connection unit (102) is formed through pre-charging to correspond to the voltage of the battery (220), and then the battery (220) is connected, thereby increasing stability.

In addition, it may include a communication unit that performs communication with a battery management device (BMS) that manages the battery (220). The communication unit receives status information such as the charge/discharge amount of the battery (220) from the battery management device, and the control unit (104) may control the first switching unit (116) or the initial charging unit using the status information of the battery. At this time, the communication unit may perform communication with the battery management device through wired or wireless communication such as CAN communication or RS-485.

The second switching unit (117) can connect or disconnect the inverter (230). A switching element that can connect the inverter (230) or separate the PV module (210) and the battery (220) from the inverter (230) can be connected to the inverter connection unit (103). When a failure occurs in the power transmission device according to an embodiment of the present invention, when the PV module (210) does not generate power due to the RSD function operation, or when a problem occurs in the battery, the second switching unit (117) can operate to separate the PV module (210) and the battery (220) from the inverter (230). The second switching unit (117) can be a relay element, or can include a DC relay, a power semiconductor element, or the like. The second switching unit (117) can be connected to the (-) power line (127) of the inverter connection unit.

The bypass unit (118) can form a bypass path on the inverter connection unit (103) when the connection with the inverter connection unit (103) is released according to the operation of the second switching unit. When the second switching unit (117) operates to separate the PV module (210) and the battery (220) from the inverter (230), the bypass path can be formed so that the power supply to the inverter (230) by other elements can be maintained. The bypass unit (118) can be composed of bypass diodes connected as shown in FIG. 3.

The power output to the inverter connector (103) may be directly applied to the inverter (230), or may be applied to the inverter (230) through the DC-DC converter (240), as shown in FIG. 5. If the voltage size of the power output to the inverter connector (103) corresponds to the voltage of the inverter (230), the DC-DC converter (240) may not be passed through. The voltage output to the inverter connector (103) may be formed through voltage control according to the charging and discharging of the battery (220). Through this, the DC-DC converter may be eliminated. However, in the case where the series battery is insufficient, the DC-DC converter (240) may be required to form the voltage required for the inverter. In addition, in the case where the battery is separated due to a battery module failure, the battery voltage cannot be used, so it may be required to convert the PV module to be suitable for the inverter module, and in the case where the charging power between the battery modules is not the same, the DC-DC converter (240) may be required to use the battery to the maximum.

A power transmission device according to an embodiment of the present invention comprises: a PV module connection unit connected to an output of a PV module; a power line communication unit connected to the (+) power line of the PV module connection unit and performing communication with the PV module; an abnormality detection unit connected to the (-) power line of the PV module connection unit and detecting an abnormality of the PV module; an input current sensing unit measuring current of the (+) power line of the PV module connection unit; a first diode connected to the (+) power line of the PV module connection unit and blocking current to the PV module; a battery connection unit connected to a battery and outputting power to the battery or receiving power from the battery; an inverter connection unit connected in parallel to the battery connection unit and outputting power to the inverter when connected to the inverter; an output current sensing unit measuring an output voltage of a front end of a node to which the battery connection unit and the inverter connection unit are connected; a first switching unit connected to the (+) power line of the battery connection unit and connecting or disconnecting the battery; an output current sensing unit measuring current of the (+) power line of the inverter connection unit; a first switching unit connected to the (-) power line of the inverter connection unit and connecting or disconnecting the inverter. The second switching unit may include a bypass unit connected to the (+) power line and the (-) power line of the inverter connection unit to form a bypass path. In addition, the unit may include an RSD unit connected between the (+) power line and the (-) power line of the PV module connection unit to lower the voltage of the PV module to a first value or lower when an abnormality in the PV module is detected, and a first capacitor connected between the (+) power line and the (-) power line of a front end of a node to which the battery connection unit and the inverter connection unit are connected. A detailed description of each component corresponds to the detailed description of each component of FIGS. 1 to 6, and thus, redundant description will be omitted.

The power transmission device (100) according to the embodiment of the present invention can be connected to other power transmission devices (200, 300, 400) to supply power to the inverter (230). At this time, the inverter connection part (103) can be connected in series with the inverter connection part of the other power transmission devices (200, 300, 400). Through this, the voltage output through each PV module (210, 310, 410, 510) and battery (220, 320, 420, 520) can be connected in series to form a required voltage, thereby making it possible to not require the DC-DC converter (240). By supplying power to the inverter (230) without going through the DC-DC converter (240), energy efficiency can be increased. In addition, when utilizing multiple power transmission devices, if a specific battery, etc. fails, a bypass unit (118) capable of bypassing the battery is included, so that power can be supplied to the inverter (230) using another battery, etc. Through such a configuration and connection relationship, the efficiency of power transmission from the PV module (210) to the battery (220), power transmission from the PV module (210) to the grid through the inverter (230), and power transmission from the battery (220) to the grid through the inverter (230) can be increased.

In addition, since the battery forms the voltage, inverter link voltage control is not required, and since the batteries are stacked in series, a DCDC converter may not be applied. In the event of a battery failure, the battery can be separated and operated. Even if the system is not operated for a long time due to reasons such as user vacation or system failure, battery over-discharge can be prevented by charging the battery with the power of the PV module (210). In addition, balancing control between batteries is possible through the control of the PV power generation amount connected to the battery, and individual charging control is possible. In addition, it can be operated as an AC-coupled product by configuring only the battery (220) without the PV module (210), and the PV module (210) can be added while operating as an AC-coupled product, and it is possible to add the battery (220) while operating as a PV-inverter product without the battery (220), and bypass operation is also possible when there is a problem with the system configured for each battery module.

In addition, when stably providing a large voltage for building or industrial use, as shown in Fig. 8, the expandability of the series-parallel design can be increased by connecting multiple battery module units connected in series in parallel with other battery module units.

In addition, a power transmission device according to an embodiment of the present invention may include a PV module connection part that receives power from a PV module, a battery connection part that is connected to a battery and outputs power to the battery or receives power from the battery, and an inverter connection part that outputs power to an inverter and is connected in parallel with the PV module connection part. As shown in FIG. 9, the PV module connection part and the inverter connection part are connected in parallel, and the battery connection part is connected to the battery so as to supply power to the inverter (230) using power of the PV module or the battery. At this time, the DC-DC converter (240) can be eliminated by connecting the batteries in series. At this time, the entire system battery management device (250) can communicate with each module battery management device (M-BMS, 251 to 254) and each power transmission device (100, 200, 300, 400), the inverter (230), and the DC-DC converter (240) through a communication line. Through these configurations and connections, the efficiency of power transmission from PV modules (210, 310, 410, 510) to batteries (220, 320, 420, 520), power transmission from PV modules (210, 310, 410, 510) to grid via inverter (230), and power transmission from batteries (220, 320, 420, 520) to grid via inverter (230) can be increased.

Those skilled in the art related to the present embodiment will understand that the above-described description can be implemented in a modified form without departing from the essential characteristics thereof. Therefore, the disclosed methods should be considered from an illustrative rather than a restrictive perspective. The scope of the present invention is indicated by the claims, not the above description, and all differences within the scope equivalent thereto should be interpreted as being included in the present invention.

Claims (10)

PV module connector that receives power from the PV module; A battery connector connected to a battery to output power to the battery or receive power from the battery; An inverter connection section that outputs power to the inverter when connected to the inverter and is connected in parallel with the battery connection section; and A power transmission device including a control unit that controls the PV module through communication with the PV module and controls the battery connection unit and the inverter connection unit to output power received from the PV module to the battery or the inverter. In the first paragraph, A power transmission device including a power line communication unit that performs communication with the PV module through a power line electrically connected to the PV module. In the first paragraph, The above PV module comprises a plurality of PV modules, A power transmission device in which the above plurality of PV modules are connected in parallel to the PV module connection part. In the first paragraph, A power transmission device including an abnormality detection unit that detects whether there is an abnormality in the PV module. In the first paragraph, A power transmission device including an RSD unit that lowers the voltage of the PV module to a first value or lower when an abnormality in the PV module is detected. In the first paragraph, An input current sensing unit for measuring the input current of the power input to the PV module connection unit; and An output voltage sensing unit for measuring the output voltage of power output from at least one of the battery connection unit and the inverter connection unit; A power transmission device including an output current sensing unit that measures the output current of power output to the inverter connection unit. In the first paragraph, A first switching unit for connecting to or disconnecting from the battery; and A power transmission device including an initial charging unit that performs initial charging when connected to the above battery. In the first paragraph, A power transmission device including a communication unit that performs communication with a battery management device that manages the above battery. In the first paragraph, A second switching unit for connecting or disconnecting the inverter; and A power transmission device including a bypass unit that forms a bypass path on the inverter connection unit when the connection with the inverter connection unit is released according to the operation of the second switching unit. In the first paragraph, The above inverter connection part is a power transmission device connected in series with the inverter connection part of another power transmission device.

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