WO2024180841A1 - Voltage converter and control method - Google Patents

Abstract

Provided is a voltage converter in which a specific indicator during voltage conversion can be improved. The voltage converter comprises: a first set of switching devices including a first switch and a second switch; a second set of switching devices including a third switch and a fourth switch; a capacitor; a transformer; detection circuits that detect an input voltage, an input current, an output voltage, and an output current; and a control circuit. The control circuit has a first control mode for controlling phase and a second control mode for controlling operation frequency. In the first control mode, the phase is changed at a predetermined cycle to a phase target value preset in accordance with the detected input voltage, a target output voltage, and a target output current. In the second control mode, the operation frequency is changed once or more during a period until the phase is next changed after the phase has been changed so that the detected output voltage becomes the target output voltage.

Description

Voltage converter and control method

This disclosure relates to a voltage converter and a method for controlling a voltage converter.

Patent Document 1 discloses a technique for adjusting the output voltage of a converter circuit to a value within the acceptable operating range even when the output voltage is not within the acceptable operating range and the operating frequency exceeds a maximum specified frequency. Specifically, the technique disclosed in Patent Document 1 first adjusts the output voltage by changing only the operating frequency, and if the output voltage does not reach the target value at the maximum frequency, the phase is changed to adjust the output voltage to a value within the acceptable operating range.

JP 2016-63745 A

There are countless combinations of operating frequency and phase to achieve a certain target voltage (target gain), but depending on the combination, certain indicators during voltage conversion, such as efficiency, may improve or deteriorate. The technology disclosed in Patent Document 1 does not take such specific indicators into account, and does not necessarily improve the specific indicator.

The present disclosure provides a voltage converter and the like that can improve specific indicators during voltage conversion.

The voltage converter according to the present disclosure includes a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path, a transformer having a primary winding and a secondary winding, one end of the primary winding connected to the resonant capacitor and the other end of the primary winding connected to the second node, and the secondary winding connected to a first output terminal and a second output terminal, and an input voltage applied between the first input terminal and the second input terminal, a voltage applied between the first input terminal and the second input terminal, and a voltage applied between the first input terminal and the second input terminal. The power supply includes a detection circuit that detects an input current input to the input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal, and a control circuit, the control circuit having a first control mode that controls a phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and a second control mode that controls an operating frequency of the first set of switching devices and the second set of switching devices, the first control mode changes the phase at a predetermined cycle toward a phase target value that is determined in accordance with the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current, and the second control mode changes the operating frequency one or more times during the period from when the phase is changed until the next time the phase is changed, so that the detected output voltage becomes the target output voltage.

The control method according to the present disclosure is a control method for a voltage converter, the voltage converter comprising: a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal; a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal; a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path; a primary winding and a secondary winding, one end of the primary winding is connected to the resonant capacitor and the other end of the primary winding is connected to the second node, the secondary winding is connected to a first output terminal and a second output terminal; and a voltage applied between the first input terminal and the second input terminal. The control method includes a first control step of controlling a phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and a second control step of controlling the operating frequency of the first set of switching devices and the second set of switching devices, and the first control step changes the phase at a predetermined cycle toward a phase target value that is determined in advance according to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current, and the second control step changes the operating frequency one or more times during the period from when the phase is changed until the next change of the phase, so that the detected output voltage becomes the target output voltage.

The voltage converter according to the present disclosure includes a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path, and a primary winding a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor and the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal; a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal; and a control circuit, wherein the control circuit controls switching of the first set of switching devices and switching of the second set of switching devices. (i) changing a phase between the input and output switching devices and an operating frequency of the first set of switching devices and the second set of switching devices to a phase reference value and an operating frequency reference value that are predetermined according to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current, and acquiring a first index calculated from the input voltage, the input current, the output voltage, or the output current detected when the phase and the operating frequency are changed to the phase reference value and the operating frequency reference value, and holding the phase reference value, the operating frequency reference value, and the first index as reference values; After changing the phase and the operating frequency to the phase reference value and the operating frequency reference value, (ii) change the phase by a fixed amount from the phase reference value, and then change the operating frequency so that the detected output voltage becomes the target output voltage. (iii) obtain a second index calculated from the input voltage, the input current, the output voltage, or the output current detected when the detected output voltage becomes the target output voltage. (iv) update the reference value according to the comparison result between the first index and the second index, and repeat the processes from (i) to (iv).

The control method according to the present disclosure is a control method for a voltage converter, the voltage converter including a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, a first node between the first switch and the second switch on the first path, and a second node between the third switch and the fourth switch on the second path. a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor and the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal; and a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal, and the control method includes detecting switching of the first set of switching devices and switching of the second set of switching devices. a phase between a switching of a switching device and a switching frequency of the first set of switching devices and the second set of switching devices to a phase reference value and an operating frequency reference value that are predetermined according to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current, and a first index is obtained that is calculated from the input voltage, the input current, the output voltage, or the output current detected when the phase and the operating frequency are changed to the phase reference value and the operating frequency reference value, and the phase reference value, the operating frequency reference value, and the first index are held as reference values. (i) changing the phase and the operating frequency to the phase reference value and the operating frequency reference value, and then changing the phase by a fixed amount from the phase reference value; (ii) changing the operating frequency so that the detected output voltage becomes the target output voltage after changing the phase by a fixed amount from the phase reference value; (iii) acquiring a second index calculated from the input voltage, the input current, the output voltage, or the output current detected when the detected output voltage becomes the target output voltage; (iv) updating the reference value according to the comparison result between the first index and the second index, and repeating the processes from (i) to (iv).

The voltage converter according to the present disclosure includes a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path, a primary winding and a secondary winding, one end of the primary winding is connected to the resonant capacitor and the other end of the primary winding is connected to the second node, and the secondary winding is connected to a first output terminal and a second output terminal, and a voltage applied between the first input terminal and the second input terminal. The input voltage, the input current input to the first input terminal, the output voltage applied between the first output terminal and the second output terminal, and the output current output from the first output terminal are detected by a detection circuit. A storage unit stores a data table in which combinations of the input voltage, the input current, the output voltage, and the output current, and combinations of phase target values and operating frequency target values are associated with each target output voltage for the output voltage. The control circuit changes the phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and the operating frequencies of the first set of switching devices and the second set of switching devices to the phase target value and the operating frequency target value obtained by comparing the detected input voltage, the input current, the output voltage, and the output current with the data table.

The control method according to the present disclosure is a control method for a voltage converter, the voltage converter including: a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal; a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal; a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path; a transformer having a primary winding and a secondary winding, one end of the primary winding connected to the resonant capacitor and the other end of the primary winding connected to the second node, the secondary winding connected to a first output terminal and a second output terminal; A detection circuit detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal; and a storage unit stores a data table in which combinations of the input voltage, the input current, the output voltage, and the output current, and combinations of phase target values and operating frequency target values are associated with each target output voltage for the output voltage. The control method changes the phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and the operating frequencies of the first set of switching devices and the second set of switching devices to the phase target values and the operating frequency target values obtained by comparing the detected input voltage, the input current, the output voltage, and the output current with the data table.

These comprehensive or specific aspects may be realized as a system, method, integrated circuit, computer program, or computer-readable recording medium such as a CD-ROM, or may be realized as any combination of a system, method, integrated circuit, computer program, and recording medium.

A voltage converter according to one embodiment of the present disclosure can improve a specific indicator during voltage conversion.

FIG. 1 is a configuration diagram illustrating an example of a voltage converter according to an embodiment. FIG. 2 is a graph showing an example of the relationship between the gain and the operating frequency of the voltage converter according to the embodiment. FIG. 3 is a flowchart showing a first operation example of the voltage converter according to the embodiment. FIG. 4 is a flowchart showing a second operation example of the voltage converter according to the embodiment. FIG. 5 is a flowchart illustrating a third operation example of the voltage converter according to the embodiment.

The following describes the embodiment in detail with reference to the drawings.

The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, the arrangement and connection of the components, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

(Embodiment)
A voltage converter according to an embodiment will be described below.

The voltage converter 1 is a DC-DC converter that steps up or down the input voltage to a specified voltage and outputs it; specifically, it is an LLC converter. The LLC converter is a circuit that utilizes LLC resonance due to the leakage inductance, excitation inductance, and resonant capacitor of the transformer T1. In an LLC converter, the input/output voltage ratio (gain) changes by changing the switching frequency (also written as the operating frequency), making it possible to output the desired voltage. Note that the gain can be calculated by (output voltage/input voltage) x (transformer turns ratio), so there is a correlation between the gain and the output voltage.

The voltage converter 1 has terminals t1, t2, t3, and t4. Terminal t1 is an example of a first input terminal and is an input terminal on the primary side of the voltage converter 1, and terminal t2 is an example of a second input terminal and is a ground terminal on the primary side of the voltage converter 1. Terminal t3 is an example of a first output terminal and is an output terminal on the secondary side of the voltage converter 1, and terminal t4 is an example of a second output terminal and is a ground terminal on the secondary side of the voltage converter 1. For example, terminals t3 and t4 are connected to the secondary winding of the transformer T1 via a rectifier circuit D10.

The voltage converter 1 includes switches Q1, Q2, Q3, and Q4, a capacitor Cr, a rectifier circuit D10, a transformer T1, a control circuit 10, an input voltage detection circuit 20, an input current detection circuit 30, an output voltage detection circuit 40, and an output current detection circuit 50. The control circuit 10, the input voltage detection circuit 20, the input current detection circuit 30, the output voltage detection circuit 40, and the output current detection circuit 50 can be realized, for example, by a microcomputer, but the method of realizing them is not particularly limited, and they may be realized by analog circuits, etc. In FIG. 1, the illustration of the circuit diagrams of the control circuit 10, the input voltage detection circuit 20, the input current detection circuit 30, the output voltage detection circuit 40, and the output current detection circuit 50 is omitted. In FIG. 1, the illustration of the signal lines connecting the control circuit 10, the input voltage detection circuit 20, the input current detection circuit 30, the output voltage detection circuit 40, and the output current detection circuit 50 to the other components is omitted.

Switches Q1 and Q2 are an example of a first set of switching devices consisting of a first switch and a second switch connected in series on a path P1 connecting terminals t1 and t2. Path P1 is an example of a first path. Hereinafter, switches Q1 and Q2 are also referred to as a first set of switching devices.

The switch Q1 is, for example, an N-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor). In FIG. 1, the parasitic capacitance of the switch Q1 is shown as a capacitor C1, which is connected in parallel with the switch Q1 in the equivalent circuit. The drain of the switch Q1 is connected to the terminal t1, and the source of the switch Q1 is connected to the drain of the switch Q2. Also, in FIG. 1, the parasitic diode of the switch Q1 is shown as a diode D1, and the anode of the diode D1 is connected to the source of the switch Q1 and the cathode is connected to the drain of the switch Q1 in the equivalent circuit.

Switch Q2 is, for example, an N-channel MOSFET. In FIG. 1, the parasitic capacitance of switch Q2 is shown as capacitor C2, and capacitor C2 is connected in parallel with switch Q2 in the equivalent circuit. The drain of switch Q2 is connected to the source of switch Q1, and the source of switch Q2 is connected to terminal t2. Also, in FIG. 1, the parasitic diode of switch Q2 is shown as diode D2, and in the equivalent circuit, the anode of diode D2 is connected to the source of switch Q2, and the cathode is connected to the drain of switch Q2.

Switches Q3 and Q4 are an example of a second set of switching devices consisting of a third switch and a fourth switch connected in series on a path P2 that connects terminals t1 and t2 and is different from path P1. Path P2 is an example of a second path. Hereinafter, switches Q3 and Q4 are also referred to as a second set of switching devices.

Switch Q3 is, for example, an N-channel MOSFET. In FIG. 1, the parasitic capacitance of switch Q3 is shown as capacitor C3, which is connected in parallel with switch Q3 in the equivalent circuit. The drain of switch Q3 is connected to terminal t1, and the source of switch Q3 is connected to the drain of switch Q4. Also, in FIG. 1, the parasitic diode of switch Q3 is shown as diode D3, and in the equivalent circuit, the anode of diode D3 is connected to the source of switch Q3, and the cathode is connected to the drain of switch Q3.

Switch Q4 is, for example, an N-channel MOSFET. In FIG. 1, the parasitic capacitance of switch Q4 is shown as capacitor C4, and capacitor C4 is connected in parallel with switch Q4 in the equivalent circuit. The drain of switch Q4 is connected to the source of switch Q3, and the source of switch Q4 is connected to terminal t2. Also, in FIG. 1, the parasitic diode of switch Q4 is shown as diode D4, and in the equivalent circuit, the anode of diode D4 is connected to the source of switch Q4, and the cathode is connected to the drain of switch Q4.

Capacitor Cr is an example of a resonant capacitor connected between node N1 between switch Q1 and switch Q2 on path P1 and node N2 between switch Q3 and switch Q4 on path P2. Node N1 is an example of a first node, and node N2 is an example of a second node.

The transformer T1 has a primary winding and a secondary winding, one end of the primary winding is connected to the capacitor Cr, the other end of the primary winding is connected to the node N2, and the secondary winding is connected to the terminals t3 and t4. Specifically, the secondary winding is connected to the terminals t3 and t4 via the rectifier circuit D10. FIG. 1 shows an equivalent circuit of the transformer T1, and the transformer T1 can be represented by an ideal transformer Tid, an excitation inductance Lm, and a leakage inductance Lr. The excitation inductance Lm is connected in parallel to the primary coil of the ideal transformer Tid, and the leakage inductance Lr is connected in series to the primary coil of the ideal transformer Tid. The voltage converter 1 may also include an inductor equivalent to the leakage inductance Lr and an inductor equivalent to the excitation inductance Lm.

The input voltage detection circuit 20 detects the voltage input to the voltage converter 1. Specifically, the input voltage detection circuit 20 detects the input voltage applied between terminals t1 and t2. The input current detection circuit 30 detects the current input to the voltage converter 1. Specifically, the input current detection circuit 30 detects the input current input to terminal t1. The output voltage detection circuit 40 detects the voltage output from the voltage converter 1. Specifically, the output voltage detection circuit 40 detects the output voltage applied between terminals t3 and t4. The output current detection circuit 50 detects the current output from the voltage converter 1. Specifically, the output current detection circuit 50 detects the output current output from terminal t3. The detected input voltage, input current, output voltage, and output current are notified to the control circuit 10.

The input voltage detection circuit 20, the input current detection circuit 30, the output voltage detection circuit 40, and the output current detection circuit 50 are examples of detection circuits.

The control circuit 10 is a circuit for controlling the switching (on and off) of the switches (e.g., switches Q1, Q2, Q3, and Q4) included in the voltage converter 1, thereby controlling the output voltage (or gain) of the voltage converter 1. For example, the control circuit 10 controls the switching of the switches Q1, Q2, Q3, and Q4 by controlling a gate drive circuit connected to the gates of the switches Q1, Q2, Q3, and Q4. Specifically, the control circuit 10 controls the phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and also controls the switching of the first set of switching devices and the operating frequency of the second set of switching devices, thereby controlling the output voltage (or gain) of the voltage converter 1. Details of the operation of the control circuit 10 will be described later.

Here, we will use Figure 2 to explain how to set the output voltage of voltage converter 1 to the target output voltage, in other words, how to set the gain of voltage converter 1 to the target gain.

FIG. 2 is a graph showing an example of the relationship between gain and operating frequency. FIG. 2 shows an example of the gain characteristics of the voltage converter 1, with the horizontal axis representing the operating frequency and the vertical axis representing the gain. Note that fr is the operating frequency when the gain is 1, and fmax is the maximum frequency at which the voltage converter 1 can operate. For example, a method of controlling the voltage converter 1 when the current gain is 1 and the target gain is 0.7 will be described.

For example, one method of changing the gain is to change the operating frequency of the switch of the voltage converter 1. As shown by arrow A in Figure 2, by changing the operating frequency, the gain can be changed from 1 to 0.7. However, as the operating frequency increases, the number of switching operations per unit time increases, resulting in greater losses and possibly worsening efficiency. Efficiency can be calculated by (output voltage x output current) / (input voltage x input current). Furthermore, the voltage converter 1 has a maximum operable frequency, and since the operating frequency cannot be controlled beyond this maximum frequency, it may not be possible to set the gain to the target gain simply by changing the operating frequency.

Also, for example, one method of changing the gain is to change the phase of switching between the switches of the voltage converter 1. By changing the phase, as shown by arrow B in Figure 2, it is possible to change the gain from 1 to 0.7 without changing the operating frequency. However, when changing the phase, it is difficult to adjust the current, and a large current may flow when the switch is turned off. This may result in large turn-off losses and poor efficiency.

Also, for example, there is a method described in Patent Document 1 as a method for changing the gain. As described above, this method first adjusts the output voltage by changing only the operating frequency, and if the output voltage does not reach the target value at the maximum frequency, changes the phase to adjust the output voltage to a value within the allowable operating range. This makes it possible to change the gain from 1 to 0.7, as indicated by arrow C in Figure 2. However, in this case, the operating frequency is increased to the maximum frequency and then the phase is changed, which may result in poor efficiency.

Then, as shown by arrow D in FIG. 2, the control circuit 10 changes the phase and operating frequency from the countless combinations of phases and operating frequencies to a combination that improves a specific indicator during voltage conversion, such as efficiency, thereby setting the gain to the target gain (in other words, setting the output voltage to the target output voltage). Below, operation examples 1 to 3 will be described as examples of the operation of the control circuit 10 that can improve a specific indicator during voltage conversion.

First, operation example 1 will be explained using Figure 3.

FIG. 3 is a flowchart showing a first operation example of the voltage converter 1 (control circuit 10) according to the embodiment. For example, in the first operation example, the control circuit 10 has a first control mode that controls the phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and a second control mode that controls the operating frequency of the first set of switching devices and the second set of switching devices.

First, the control circuit 10 detects the input voltage (step S101). Specifically, the control circuit 10 obtains the input voltage detected by the input voltage detection circuit 20.

Next, the control circuit 10 performs control in the first control mode. Specifically, the control circuit 10 performs the processes in steps S102 and S103 in the first control mode.

The control circuit 10 changes the phase between the switching of the first group of switching devices and the switching of the second group of switching devices (hereinafter also simply referred to as phase) toward a predetermined phase target value according to the detected input voltage, the target output voltage for the output voltage, and the target output current for the output current (step S102). For example, the voltage converter 1 has a storage unit that stores a data table in which combinations of input voltage, target output voltage, and target output current are associated with phase target values, and the control circuit 10 determines the phase target value using the data table and changes the phase toward the determined phase target value. The control circuit 10 changes the phase at a predetermined cycle. Specifically, after performing the process in step S102, if the result in step S103 described below is No, the control circuit 10 performs the process in step S102 again after a certain time has elapsed.

For example, the data table associates a phase target value that improves a specific index with each combination of input voltage, target output voltage, and target output current. The specific index is, for example, efficiency, operating frequency, current flowing through the switch at turn-off, voltage applied to the switch at turn-on, output ripple voltage, or noise level. In other words, the data table associates a phase target value that improves efficiency, makes the operating frequency a desired operating frequency, reduces the current at turn-off, reduces the voltage at turn-on, reduces the output ripple voltage, or reduces noise with each combination of input voltage, target output voltage, and target output current. The phase target value that improves a specific index can be determined in advance for each combination of input voltage, target output voltage, and target output current, for example, by experiments or past operating history.

In this way, the data table associates combinations of input voltage, target output voltage, and target output current that improve a specific indicator during voltage conversion with phase target values, so by comparing the detected input voltage and the target output voltage and target output current with the data table, it is possible to determine a phase target value that can improve a specific indicator.

Next, the control circuit 10 judges whether the phase has reached the phase target value (step S103). For example, if the phase is changed significantly at once, the output voltage will deviate significantly from the target output voltage, making it difficult to search for an operating frequency for making the output voltage the target output voltage, which is performed in steps S104 to S106 described below. Therefore, the processing from steps S102 to S106 is repeated, and in this repetition, the phase is gradually brought closer to the phase target value in step S102. After the judgment in step S103, the control circuit 10 performs control in the second control mode. Specifically, the control circuit 10 performs the processing from steps S104 to S106, or the processing from steps S107 to S109, in the second control mode.

If the control circuit 10 determines that the phase has not reached the phase target value (No in step S103), it detects the output voltage (step S104). Specifically, the control circuit 10 obtains the output voltage detected by the output voltage detection circuit 40.

Next, the control circuit 10 determines whether the output voltage is the target output voltage (step S105). For example, since the output voltage changes when the phase is changed, the control circuit 10 changes the operating frequency in the second control mode so that the output voltage becomes the target output voltage.

When the control circuit 10 determines that the output voltage is not the target output voltage (No in step S105), it changes the operating frequency so that the detected output voltage becomes the target output voltage (step S106). Since a single change in the operating frequency does not necessarily result in the output voltage becoming the target output voltage, after the processing in step S102 is performed, the processing from step S104 to step S106 is performed one or more times during the period until the next processing in step S102 is performed so that the output voltage becomes the target output voltage.

If the control circuit 10 determines that the output voltage is the target output voltage (Yes in step S105), in step S102, it changes the phase by a certain amount toward the phase target value, and repeats the processing from step S103 onwards.

The control circuit 10 may also detect the output current in step S104. In this case, it is also determined in step S105 whether the output current is the target output current, and if the output voltage is the target output voltage and the output current is the target output current, the process returns to step S102, and if the output voltage is not the target output voltage or the output current is not the target output current, the process proceeds to step S106.

If the control circuit 10 determines that the phase has reached the phase target value (Yes in step S103), it performs steps S107 to S109, which are basically the same as steps S104 to S106. Specifically, step S107 corresponds to step S104, step S108 corresponds to step S105, and step S109 corresponds to step S106. However, if the control circuit 10 determines that the output voltage is the target output voltage (Yes in step S108), the phase is already at the phase target value, and there is no need to change the phase toward the phase target value in step S102, so it ends the process.

In this way, in the first control mode, the control circuit 10 changes the phase at a predetermined period toward a predetermined phase target value according to the detected input voltage, as well as the target output voltage for the output voltage and the target output current for the output current, and in the second control mode, after the phase is changed, during the period until the next phase change, the control circuit 10 changes the operating frequency one or more times so that the detected output voltage becomes the target output voltage.

In operation example 1, the phase target value, which is determined in advance according to the detected input voltage, as well as the target output voltage and target output current, is a value that improves a specific index during voltage conversion, and the specific index can be improved by changing the phase toward the phase target value in the first control mode. However, since it is difficult to make the output voltage the target output voltage by simply changing the phase, after the phase is changed, during the period until the next phase change, the operating frequency is changed one or more times to search for an operating frequency that will make the output voltage the target output voltage. This makes it possible to improve the specific index during voltage conversion while keeping the output voltage the target output voltage.

Furthermore, if the phase is changed significantly all at once, the output voltage will deviate significantly from the target output voltage, making it difficult to find an operating frequency that will make the output voltage the target output voltage. Therefore, the control circuit 10 repeatedly changes the phase in the first control mode and the operating frequency in the second control mode while gradually bringing the phase closer to the phase target value. In this way, by repeatedly changing the phase and the operating frequency after the phase change while gradually bringing the phase closer to the phase target value, it becomes easier to make the output voltage the target output voltage.

Next, operation example 2 will be explained using Figure 4.

FIG. 4 is a flowchart showing a second operation example of the voltage converter 1 (control circuit 10) according to the embodiment.

First, the control circuit 10 detects the input voltage (step S201). Specifically, the control circuit 10 obtains the input voltage detected by the input voltage detection circuit 20.

Next, the control circuit 10 changes the phase (hereinafter also simply referred to as phase) between the switching of the first set of switching devices and the switching of the second set of switching devices, and the operating frequency (hereinafter also simply referred to as operating frequency) of the first set of switching devices and the second set of switching devices to a phase reference value and an operating frequency reference value that are determined in advance according to the detected input voltage, and the target output voltage for the output voltage and the target output current for the output current (step S202). For example, the voltage converter 1 includes a storage unit that stores a data table in which combinations of input voltage, target output voltage, and target output current are associated with combinations of phase reference values and operating frequency reference values, and the control circuit 10 determines the phase reference value and operating frequency reference value using the data table, and changes the phase and operating frequency to the determined phase reference value and operating frequency reference value.

For example, the data table associates a phase reference value and an operating frequency reference value that improve a specific index with each combination of input voltage, target output voltage, and target output current. The specific index is, for example, efficiency, operating frequency, current flowing through the switch at turn-off, voltage applied to the switch at turn-on, output ripple voltage, or noise level. In other words, the data table associates a combination of phase reference values and operating frequency reference values that improve efficiency, make the operating frequency a desired operating frequency, reduce the current at turn-off, reduce the voltage at turn-on, reduce the output ripple voltage, or reduce noise with each combination of input voltage, target output voltage, and target output current. The combination of phase reference values and operating frequency reference values that improve a specific index can be determined in advance for each combination of input voltage, target output voltage, and target output current, for example, by experiments or past operating history.

In this way, the data table associates combinations of input voltage, target output voltage, and target output current with combinations of phase reference values and operating frequency reference values, so that the initial phase reference value and operating frequency reference value can be determined by comparing the detected input voltage and the target output voltage and target output current with the data table.

Then, the control circuit 10 acquires a first index calculated from the input voltage, input current, output voltage, and output current detected when the phase and operating frequency are changed to the phase reference value and operating frequency reference value (step S203). As described above, the first index is, for example, the efficiency, operating frequency, the current flowing through the switch when turned off, the voltage applied to the switch when turned on, the output ripple voltage, or the magnitude of noise.

Next, the control circuit 10 stores the phase reference value, the operating frequency reference value, and the first index as reference values in a memory unit or the like (step S204).

Next, the control circuit 10 changes the phase and operating frequency to the phase reference value and the operating frequency reference value, and then changes the phase by a certain amount from the phase reference value (step S205). The certain amount is not particularly limited, but if the phase is changed significantly all at once, it becomes difficult to search for an operating frequency for making the output voltage the target output voltage, which is performed in steps S206 to S208 described below, so for example, the certain amount is a relatively small amount.

Next, the control circuit 10 detects the output voltage after changing the phase by a certain amount from the phase reference value (step S206). Specifically, the control circuit 10 obtains the output voltage detected by the output voltage detection circuit 40.

Next, the control circuit 10 determines whether the output voltage is the target output voltage (step S207). For example, since the output voltage changes when the phase is changed, the control circuit 10 changes the operating frequency so that the output voltage becomes the target output voltage.

If the control circuit 10 determines that the detected output voltage is not the target output voltage (No in step S207), it changes the operating frequency so that the detected output voltage becomes the target output voltage (step S208). Since a single change in the operating frequency does not necessarily result in the output voltage becoming the target output voltage, the process from step S206 to step S208 is performed one or more times so that the output voltage becomes the target output voltage.

When the control circuit 10 determines that the detected output voltage is the target output voltage (Yes in step S207), it acquires a second index calculated from the input voltage, input current, output voltage, or output current detected when the detected output voltage becomes the target output voltage (step S209). As described above, the second index is, for example, the efficiency, operating frequency, the current flowing through the switch when turned off, the voltage applied to the switch when turned on, the output ripple voltage, or the magnitude of noise.

The control circuit 10 may also detect the output current in step S206. In this case, it is also determined in step S207 whether the output current is the target output current, and if the output voltage is the target output voltage and the output current is the target output current, the process proceeds to step S209, and if the output voltage is not the target output voltage or the output current is not the target output current, the process proceeds to step S208.

Then, the control circuit 10 compares the first index with the second index, and determines whether the second index is better than the first index (step S210). For example, if the first index and the second index are efficiency, it determines whether the efficiency is better when the phase is changed by a certain amount from the phase reference value and the operating frequency is changed than the efficiency when the phase and operating frequency are changed to the phase reference value and the operating frequency reference value.

If the second index is better than the first index (Yes in step S210), the control circuit 10 updates the reference value (step S211). Specifically, the value of the first index in the held reference value is updated to the value of the second index, the value of the phase reference value in the held reference value is updated to the changed phase value, and the value of the operating frequency reference value in the held reference value is updated to the changed operating frequency value. The control circuit 10 then uses the updated reference value to perform the processes from step S205 onwards again.

If the second index is worse than the first index or the indexes are the same (No in step S210), in step S205 the control circuit 10 changes the phase from the phase reference value by an amount different from the previous time, and repeats the processing from step S206 onwards.

In this way, the control circuit 10 (i) changes the phase and operating frequency to the phase reference value and operating frequency reference value, and then changes the phase by a fixed amount from the phase reference value, (ii) changes the operating frequency so that the detected output voltage becomes the target output voltage after changing the phase by a fixed amount from the phase reference value, (iii) obtains a second index calculated from the input voltage, input current, output voltage, or output current detected when the detected output voltage becomes the target output voltage, and (iv) updates the reference value according to the comparison result between the first index and the second index, and repeats the processes from (i) to (iv) above.

In operation example 2, when the second index, which is a specific index when the phase and operating frequency are changed from a state in which they are reference values (a phase reference value and an operating frequency reference value in which a specific index during voltage conversion becomes a first index), is better than the first index, the reference values (the first index, the phase reference value and the operating frequency reference value) are updated to the second index and the changed phase and operating frequency. Then, the phase and operating frequency are changed again from a state in which they are the updated reference values (i.e., the phase and operating frequency when they became the previous second index). By repeating this, the specific index can be improved. Therefore, the specific index during voltage conversion can be improved.

For example, the control circuit 10 may perform PI control of the phase and the operating frequency according to the comparison result between the first index and the second index. Specifically, if a second index that is better than the first index that is the current reference value is not found even after repeating the process from step S205 to step S210 multiple times, the current first index may be regarded as the optimal index, and PI control of the phase and the operating frequency may be performed so that the current first index is maintained. Also, if a second index that is better than the first index that is the current reference value is not found even after repeating the process from step S205 to step S210 multiple times, a more optimal index may be searched for by changing the phase by a smaller amount of change than the previous time with respect to the current phase reference value.

Note that in the process (i) above, if the detected output voltage becomes the target output voltage after the phase is shifted by a certain amount from the phase reference value, the control circuit 10 does not need to perform the process (ii) above. In this way, if the output voltage becomes the target output voltage simply by changing the phase, there is no need to change the operating frequency.

Next, operation example 3 will be explained using Figure 5.

FIG. 5 is a flowchart showing an operation example 3 of the voltage converter 1 (control circuit 10) according to the embodiment. In the operation example 3, the voltage converter 1 is provided with a storage unit that stores a data table in which combinations of input voltage, input current, output voltage, and output current, and combinations of phase target values and operating frequency target values are associated with each target output voltage for the output voltage.

First, the control circuit 10 detects the input voltage, input current, output voltage, and output current (step S301). Specifically, the control circuit 10 obtains the input voltage detected by the input voltage detection circuit 20, the input current detected by the input current detection circuit 30, the output voltage detected by the output voltage detection circuit 40, and the output current detected by the output current detection circuit 50.

Next, the control circuit 10 changes the phase (hereinafter also simply referred to as phase) between the switching of the first set of switching devices and the switching of the second set of switching devices, and the operating frequency (hereinafter also simply referred to as operating frequency) of the first set of switching devices and the second set of switching devices to a phase target value and an operating frequency target value obtained by comparing the detected input voltage, input current, output voltage, and output current with a data table (step S302).

For example, in the data table, for each combination of input voltage, input current, output voltage, and output current, a phase target value and an operating frequency target value that improve a specific index are associated, and this correspondence exists for each target output voltage. The specific index is, for example, efficiency, operating frequency, current flowing through the switch at turn-off, voltage applied to the switch at turn-on, output ripple voltage, or noise level. In other words, in the data table, for each combination of input voltage, input current, output voltage, and output current, and target output voltage, a combination of phase target value and operating frequency target value that improves efficiency, makes the operating frequency a desired operating frequency, reduces the current at turn-off, reduces the voltage at turn-on, reduces the output ripple voltage, or reduces noise is associated. The combination of phase target value and operating frequency target value that improves a specific index can be determined in advance for each combination of input voltage, input current, output voltage, and output current, and target output voltage, for example, by experiments or past operating history.

In this way, the data table associates, for each target output voltage, a combination of input voltage, input current, output voltage, and output current, and a combination of phase target value and operating frequency target value that improves a specific index during voltage conversion. Therefore, by comparing the detected input voltage, input current, output voltage, and output current, as well as the target output voltage, with the data table, it is possible to determine a phase target value and operating frequency target value that can improve the specific index. Therefore, by changing the phase and operating frequency to the determined phase target value and operating frequency target value, it is possible to improve the specific index during voltage conversion.

Other Embodiments
As described above, the embodiment has been described as an example of the technology according to the present disclosure. However, the technology according to the present disclosure is not limited to this, and can be applied to an embodiment in which appropriate changes, substitutions, additions, omissions, etc. are made. For example, the following modified examples are also included in one embodiment of the present disclosure.

For example, in the above-described operation example 1 of the embodiment, an example has been described in which the control circuit 10 repeatedly changes the phase in the first control mode and the operating frequency in the second control mode while gradually bringing the phase closer to the phase target value, but this is not limiting. For example, the control circuit 10 does not need to gradually change the phase toward the phase target value, and may change the phase directly to the phase target value. In other words, the processes from step S104 to step S106 in FIG. 3 do not need to be performed.

For example, the present disclosure can be realized not only as a voltage converter 1, but also as a control method for the voltage converter 1 that includes steps (processing) performed by components that make up the voltage converter 1 (specifically, the control circuit 10).

The control method corresponding to the above-mentioned operation example 1 is a control method for a voltage converter 1, in which the voltage converter 1 includes a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path, a transformer having a primary winding and a secondary winding, one end of the primary winding connected to the resonant capacitor and the other end of the primary winding connected to the second node, and a secondary winding connected to a first output terminal and a second output terminal, and an input voltage applied between the first input terminal and the second input terminal, a first input voltage applied between the first input terminal and the second input terminal, a second input voltage applied between the first input terminal and the second input terminal, a third input voltage applied between the first input terminal and the second input terminal, a fourth input voltage applied between the first input terminal and the second input terminal, a fifth input voltage applied between the first input terminal and the second input terminal, a sixth input voltage applied between the first input terminal and the second input terminal, a seventh ... The control method includes a first control step of controlling the phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and a second control step of controlling the operating frequency of the first set of switching devices and the second set of switching devices, as shown in FIG. 3. In the first control step, the phase is changed at a predetermined period toward a phase target value that is determined in advance according to the detected input voltage, the target output voltage for the output voltage, and the target output current for the output current (step S102). In the second control step, the operating frequency is changed one or more times during the period from when the phase is changed until the next change of the phase, so that the detected output voltage becomes the target output voltage (step S106).

The control method corresponding to the above-mentioned operation example 2 is a control method of the voltage converter 1, in which the voltage converter 1 includes a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, and a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path. a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor and the other end of the primary winding being connected to a second node, and the secondary winding being connected to a first output terminal and a second output terminal; and a detection circuit for detecting an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal. The control method includes, as shown in FIG. 4, detecting an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal. The phase between the first set of switching devices and the second set of switching devices is changed to a phase reference value and an operating frequency reference value that are predetermined according to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current (step S202), a first index is obtained that is calculated from the input voltage, input current, output voltage, or output current detected when the phase and the operating frequency are changed to the phase reference value and the operating frequency reference value (step S203), and the phase reference value, the operating frequency reference value, and the first index are held as reference values (step S204); (i) the phase and After changing the phase and operating frequency to the phase reference value and operating frequency reference value, the phase is changed by a certain amount from the phase reference value (step S205); (ii) after changing the phase by a certain amount from the phase reference value, the operating frequency is changed so that the detected output voltage becomes the target output voltage (step S208); (iii) a second index is obtained that is calculated from the input voltage, input current, output voltage, or output current detected when the detected output voltage becomes the target output voltage (step S209); (iv) the reference value is updated according to the comparison result between the first index and the second index (step S211), and the above processes from (i) to (iv) are repeated.

The control method corresponding to the above operation example 3 is a control method for a voltage converter 1, in which the voltage converter 1 includes: a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal; a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal; a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path; a transformer having a primary winding and a secondary winding, one end of the primary winding connected to the resonant capacitor and the other end of the primary winding connected to the second node, and the secondary winding connected to a first output terminal and a second output terminal; The control method includes a detection circuit that detects the input voltage applied between the input terminal, the input current input to the first input terminal, the output voltage applied between the first output terminal and the second output terminal, and the output current output from the first output terminal, and a storage unit that stores a data table in which combinations of the input voltage, the input current, the output voltage, and the output current, and combinations of the phase target value and the operating frequency target value are associated with each target output voltage for the output voltage, and changes the phase between the switching of the first set of switching devices and the switching of the second set of switching devices, as well as the operating frequencies of the first set of switching devices and the second set of switching devices, to the phase target value and the operating frequency target value obtained by comparing the detected input voltage, input current, output voltage, and output current with the data table (step S302).

For example, the present disclosure can be realized as a program for causing a computer (processor) to execute the steps included in the control method. Furthermore, the present disclosure can be realized as a non-transitory computer-readable recording medium, such as a CD-ROM, on which the program is recorded.

For example, when the present disclosure is realized as a program (software), each step is performed by running the program using hardware resources such as a computer's CPU, memory, and input/output circuits. In other words, each step is performed by the CPU obtaining data from memory or input/output circuits, etc., performing calculations, and outputting the results of the calculations to memory or input/output circuits, etc.

In the above embodiment, each component included in the voltage converter 1 may be configured with dedicated hardware, or may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

Some or all of the functions of the voltage converter 1 according to the above embodiment are typically realized as an LSI, which is an integrated circuit. These may be individually integrated into one chip, or may be integrated into one chip that includes some or all of the functions. Furthermore, the integrated circuit is not limited to an LSI, and may be realized by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after LSI manufacture, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells inside the LSI may also be used.

Furthermore, if an integrated circuit technology that can replace LSIs emerges due to advances in semiconductor technology or other derived technologies, it is natural that each component included in the voltage converter 1 may be integrated using that technology.

In addition, this disclosure also includes forms obtained by applying various modifications to the embodiments that a person skilled in the art may conceive, and forms realized by arbitrarily combining the components and functions of each embodiment within the scope that does not deviate from the spirit of this disclosure.

(Additional Note)
The above description of the embodiments discloses the following techniques.

　(Technology 1) A transformer having a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path, a primary winding and a secondary winding, one end of the primary winding is connected to the resonant capacitor and the other end of the primary winding is connected to the second node, and the secondary winding is connected to a first output terminal and a second output terminal, an input voltage applied between the first input terminal and the second input terminal, A voltage converter comprising: a detection circuit that detects an input current, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal; and a control circuit, the control circuit having a first control mode that controls a phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and a second control mode that controls an operating frequency of the first set of switching devices and the second set of switching devices, in which in the first control mode, the phase is changed at a predetermined cycle toward a phase target value that is determined in advance according to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current, and in the second control mode, the operating frequency is changed one or more times during the period from when the phase is changed until the next time the phase is changed, so that the detected output voltage becomes the target output voltage.

The phase target value, which is determined in advance according to the detected input voltage, as well as the target output voltage and target output current, is a value that improves a specific index during voltage conversion, and by changing the phase toward the phase target value in the first control mode, the specific index can be improved. However, since it is difficult to make the output voltage the target output voltage by simply changing the phase, after the phase is changed, during the period until the next phase change, the operating frequency is changed one or more times to search for an operating frequency that will make the output voltage the target output voltage. This makes it possible to improve the specific index during voltage conversion while keeping the output voltage the target output voltage.

(Technology 2) The voltage converter according to Technology 1 includes a storage unit that stores a data table in which combinations of the input voltage, the target output voltage, and the target output current correspond to the phase target value, and the control circuit determines the phase target value using the data table.

In this way, the data table associates combinations of input voltage, target output voltage, and target output current that improve a specific indicator during voltage conversion with phase target values, so by comparing the detected input voltage and the target output voltage and target output current with the data table, it is possible to determine a phase target value that can improve a specific indicator.

(Technology 3) A voltage converter as described in Technology 1 or 2, in which the control circuit repeatedly changes the phase in the first control mode and the operating frequency in the second control mode while gradually bringing the phase closer to the phase target value.

If the phase is changed significantly all at once, the output voltage will deviate significantly from the target output voltage, making it difficult to find the operating frequency that will make the output voltage the target output voltage. Therefore, by gradually bringing the phase closer to the phase target value, and repeating the phase change and the change in the operating frequency after the phase change, it becomes easier to make the output voltage the target output voltage.

(Technology 4) A method for controlling a voltage converter, the voltage converter comprising: a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal; a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal; a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path; a transformer having a primary winding and a secondary winding, one end of the primary winding connected to the resonant capacitor and the other end of the primary winding connected to the second node, the secondary winding connected to a first output terminal and a second output terminal; The control method includes a detection circuit that detects an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal. The control method includes a first control step of controlling a phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and a second control step of controlling an operating frequency of the first set of switching devices and the second set of switching devices. In the first control step, the phase is changed at a predetermined cycle toward a phase target value that is determined in advance according to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current. In the second control step, the operating frequency is changed one or more times during the period from when the phase is changed until the next time the phase is changed, so that the detected output voltage becomes the target output voltage.

This makes it possible to provide a control method that can improve a specific indicator during voltage conversion while keeping the output voltage at a target output voltage.

(Technology 5) A first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path, and a primary winding and a secondary winding. a transformer having one end of the primary winding connected to the resonant capacitor, the other end of the primary winding connected to the second node, and the secondary winding connected to a first output terminal and a second output terminal; a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal; and a control circuit, wherein the control circuit detects a transition between switching of the first set of switching devices and switching of the second set of switching devices. (i) changing a phase and an operating frequency of the first set of switching devices and the second set of switching devices to a phase reference value and an operating frequency reference value that are predetermined according to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current, and acquiring a first index calculated from the input voltage, the input current, the output voltage, or the output current detected when the phase and the operating frequency are changed to the phase reference value and the operating frequency reference value, and holding the phase reference value, the operating frequency reference value, and the first index as reference values; A voltage converter that changes the operating frequency to the phase reference value and the operating frequency reference value, then changes the phase by a fixed amount from the phase reference value, (ii) changes the operating frequency so that the detected output voltage becomes the target output voltage after changing the phase by a fixed amount from the phase reference value, (iii) obtains a second index calculated from the input voltage, the input current, the output voltage, or the output current detected when the detected output voltage becomes the target output voltage, (iv) updates the reference value according to a comparison result between the first index and the second index, and repeats the processes from (i) to (iv).

If the second index, which is a specific index when the phase and operating frequency are changed from a state in which they are reference values (phase reference value and operating frequency reference value in which the specific index during voltage conversion becomes the first index), is better than the first index, the reference values (first index, phase reference value and operating frequency reference value) are updated to the second index and the changed phase and operating frequency. Then, the phase and operating frequency are changed again from a state in which they are the updated reference values (i.e., the phase and operating frequency when they became the previous second index). By repeating this, the specific index can be improved. Therefore, the specific index during voltage conversion can be improved.

(Technology 6) The voltage converter according to Technology 5 includes a storage unit that stores a data table in which combinations of the input voltage, the target output voltage, and the target output current correspond to combinations of the phase reference value and the operating frequency reference value, and the control circuit determines the phase reference value and the operating frequency reference value using the data table.

In this way, the data table associates combinations of input voltage, target output voltage, and target output current with combinations of phase reference values and operating frequency reference values, so that the initial phase reference value and operating frequency reference value can be determined by comparing the detected input voltage and the target output voltage and target output current with the data table.

(Technology 7) A voltage converter according to Technology 5 or 6, in which the first indicator and the second indicator are efficiency, operating frequency, current flowing through the switch when turned off, voltage applied to the switch when turned on, output ripple voltage, or noise magnitude.

This makes it possible to increase efficiency during voltage conversion, set the operating frequency to the desired operating frequency, reduce the current and voltage at turn-off, and reduce output ripple voltage and noise.

(Technology 8) A voltage converter according to any one of techniques 5 to 7, in which the control circuit performs PI control of the phase and the operating frequency according to a comparison result between the first index and the second index.

This allows PI control to control a specific indicator to become a target indicator.

(Technology 9) A voltage converter according to any one of techniques 5 to 8, in which the control circuit does not perform process (ii) if the detected output voltage becomes the target output voltage after the phase is changed by a certain amount from the phase reference value in process (i).

For example, there are cases where the output voltage becomes the target output voltage simply by changing the phase. In this case, there is no need to change the operating frequency.

(Technology 10) A method for controlling a voltage converter, the voltage converter comprising: a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal; a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal; and a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path. a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor and the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal; and a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal, and the control method includes detecting switching of the first set of switching devices and switching of the second set of switching devices. (i) changing a phase between switching and the first set of switching devices and an operating frequency of the first set of switching devices and the second set of switching devices to a phase reference value and an operating frequency reference value that are predetermined according to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current, and acquiring a first index calculated from the input voltage, the input current, the output voltage, or the output current detected when the phase and the operating frequency are changed to the phase reference value and the operating frequency reference value, and holding the phase reference value, the operating frequency reference value, and the first index as reference values; A control method that changes the phase and the operating frequency to the phase reference value and the operating frequency reference value, and then changes the phase by a fixed amount from the phase reference value, (ii) changes the operating frequency so that the detected output voltage becomes the target output voltage after changing the phase by a fixed amount from the phase reference value, (iii) obtains a second index calculated from the input voltage, the input current, the output voltage, or the output current detected when the detected output voltage becomes the target output voltage, (iv) updates the reference value according to a comparison result between the first index and the second index, and repeats the processes from (i) to (iv).

This provides a control method that can improve specific indicators during voltage conversion.

(Technology 11) A transformer having a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal, a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal, a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path, a primary winding and a secondary winding, one end of the primary winding is connected to the resonant capacitor and the other end of the primary winding is connected to the second node, and the secondary winding is connected to a first output terminal and a second output terminal, and an input voltage applied between the first input terminal and the second input terminal, A voltage converter including: a detection circuit that detects an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal; a storage unit that stores a data table in which combinations of the input voltage, the input current, the output voltage, and the output current, and combinations of phase target values and operating frequency target values are associated with each target output voltage for the output voltage; and a control circuit, wherein the control circuit changes the phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and the operating frequencies of the first set of switching devices and the second set of switching devices to the phase target values and the operating frequency target values obtained by comparing the detected input voltage, the input current, the output voltage, and the output current with the data table.

Accordingly, the data table associates, for each target output voltage, a combination of input voltage, input current, output voltage, and output current, and a combination of phase target value and operating frequency target value that improves a specific index during voltage conversion, so that by comparing the detected input voltage, input current, output voltage, and output current, as well as the target output voltage, with the data table, it is possible to determine a phase target value and operating frequency target value that can improve the specific index. Therefore, by changing the phase and operating frequency to the determined phase target value and operating frequency target value, it is possible to improve the specific index during voltage conversion.

(Technology 12) A method for controlling a voltage converter, the voltage converter comprising: a first set of switching devices consisting of a first switch and a second switch connected in series on a first path connecting a first input terminal and a second input terminal; a second set of switching devices consisting of a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal; a resonant capacitor connected between a first node between the first switch and the second switch on the first path and a second node between the third switch and the fourth switch on the second path; a transformer having a primary winding and a secondary winding, one end of the primary winding connected to the resonant capacitor and the other end of the primary winding connected to the second node, the secondary winding connected to a first output terminal and a second output terminal; The control method includes a detection circuit that detects an input current input to a first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal, and a storage unit that stores a data table in which combinations of the input voltage, the input current, the output voltage, and the output current, and combinations of phase target values and operating frequency target values are associated with each target output voltage for the output voltage. The control method obtains the detected input voltage, the input current, the output voltage, and the output current, and changes the phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and the operating frequencies of the first set of switching devices and the second set of switching devices to the phase target values and the operating frequency target values obtained by comparing the detected input voltage, the input current, the output voltage, and the output current with the data table.

This provides a control method that can improve specific indicators during voltage conversion.

This disclosure can be applied to voltage converters such as LLC converters.

1 Voltage converter 10 Control circuit 20 Input voltage detection circuit 30 Input current detection circuit 40 Output voltage detection circuit 50 Output current detection circuit C1, C2, C3, C4, Cr Capacitor D1, D2, D3, D4 Diode D10 Rectifier circuit Lm Excitation inductance Lr Leakage inductance N1, N2 Node P1, P2 Path Q1, Q2, Q3, Q4 Switch T1 Transformer Tid Ideal transformer t1, t2, t3, t4 Terminal

Claims (12)

a first set of switching devices including a first switch and a second switch connected in series on a first path connecting the first input terminal and the second input terminal;
a second set of switching devices including a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal;
a resonant capacitor connected between a first node on the first path between the first switch and the second switch and a second node on the second path between the third switch and the fourth switch;
a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor, the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal;
a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal;
A control circuit,
The control circuit includes:
a first control mode for controlling a phase between the switching of the first set of switching devices and the switching of the second set of switching devices;
a second control mode for controlling an operating frequency of the first set of switching devices and the second set of switching devices;
In the first control mode, the phase is changed at a predetermined period toward a phase target value that is determined in advance in response to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current;
In the second control mode, after the phase is changed, during a period until the phase is next changed, the operating frequency is changed one or more times so that the detected output voltage becomes the target output voltage.
Voltage converter. the voltage converter includes a storage unit configured to store a data table in which combinations of the input voltage, the target output voltage, and the target output current are associated with the phase target value;
The control circuit determines the phase target value using the data table.
The voltage converter according to claim 1 . the control circuit repeatedly changes the phase in the first control mode and the operating frequency in the second control mode while gradually bringing the phase closer to the phase target value;
3. A voltage converter according to claim 1 or 2. A method for controlling a voltage converter, comprising the steps of:
The voltage converter includes:
a first set of switching devices including a first switch and a second switch connected in series on a first path connecting the first input terminal and the second input terminal;
a second set of switching devices including a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal;
a resonant capacitor connected between a first node on the first path between the first switch and the second switch and a second node on the second path between the third switch and the fourth switch;
a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor, the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal;
a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal,
The control method includes:
a first control step of controlling a phase between the switching of the first set of switching devices and the switching of the second set of switching devices;
a second control step of controlling an operating frequency of the first set of switching devices and the second set of switching devices;
In the first control step, the phase is changed at a predetermined cycle toward a phase target value that is determined in advance in response to the detected input voltage, a target output voltage for the output voltage, and a target output current for the output current;
In the second control step, the operating frequency is changed one or more times during a period until the next change of the phase after the phase is changed, so that the detected output voltage becomes the target output voltage.
Control methods. a first set of switching devices including a first switch and a second switch connected in series on a first path connecting the first input terminal and the second input terminal;
a second set of switching devices including a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal;
a resonant capacitor connected between a first node on the first path between the first switch and the second switch and a second node on the second path between the third switch and the fourth switch;
a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor, the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal;
a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal;
A control circuit,
The control circuit includes:
changing a phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and an operating frequency of the first set of switching devices and the second set of switching devices to a predetermined phase reference value and an operating frequency reference value in response to the sensed input voltage, a target output voltage for the output voltage, and a target output current for the output current;
acquiring a first index calculated from the input voltage, the input current, the output voltage, or the output current detected when the phase and the operating frequency are changed to the phase reference value and the operating frequency reference value;
holding the phase reference value, the operating frequency reference value and the first indicator as reference values;
(i) changing the phase and the operating frequency to the phase reference value and the operating frequency reference value, and then changing the phase from the phase reference value by a fixed amount;
(ii) changing the operating frequency such that the detected output voltage becomes the target output voltage after the phase is changed by a certain amount from the phase reference value;
(iii) obtaining a second index calculated from the input voltage, the input current, the output voltage, or the output current detected when the detected output voltage becomes the target output voltage;
(iv) updating the reference value according to a comparison result between the first indicator and the second indicator;
Repeating the processes (i) to (iv);
Voltage converter. the voltage converter includes a storage unit configured to store a data table in which combinations of the input voltage, the target output voltage, and the target output current are associated with combinations of the phase reference value and the operating frequency reference value;
the control circuit determines the phase reference value and the operating frequency reference value using the data table;
The voltage converter according to claim 5 . The first index and the second index are efficiency, an operating frequency, a current flowing through a switch when turned off, a voltage applied to a switch when turned on, an output ripple voltage, or a noise level.
7. A voltage converter according to claim 5 or 6. the control circuit performs PI control of the phase and the operating frequency in response to a comparison result between the first index and the second index.
7. A voltage converter according to claim 5 or 6. the control circuit does not perform the process of (ii) when the detected output voltage becomes the target output voltage after the phase is changed by a certain amount from the phase reference value in the process of (i);
7. A voltage converter according to claim 5 or 6. A method for controlling a voltage converter, comprising the steps of:
The voltage converter includes:
a first set of switching devices including a first switch and a second switch connected in series on a first path connecting the first input terminal and the second input terminal;
a second set of switching devices including a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal;
a resonant capacitor connected between a first node on the first path between the first switch and the second switch and a second node on the second path between the third switch and the fourth switch;
a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor, the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal;
a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal,
The control method includes:
changing a phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and an operating frequency of the first set of switching devices and the second set of switching devices to a predetermined phase reference value and an operating frequency reference value in response to the sensed input voltage, a target output voltage for the output voltage, and a target output current for the output current;
acquiring a first index calculated from the input voltage, the input current, the output voltage, or the output current detected when the phase and the operating frequency are changed to the phase reference value and the operating frequency reference value;
holding the phase reference value, the operating frequency reference value and the first indicator as reference values;
(i) changing the phase and the operating frequency to the phase reference value and the operating frequency reference value, and then changing the phase from the phase reference value by a fixed amount;
(ii) changing the operating frequency such that the detected output voltage becomes the target output voltage after the phase is changed by a certain amount from the phase reference value;
(iii) obtaining a second index calculated from the input voltage, the input current, the output voltage, or the output current detected when the detected output voltage becomes the target output voltage;
(iv) updating the reference value according to a comparison result between the first indicator and the second indicator;
Repeating the processes (i) to (iv);
Control methods. a first set of switching devices including a first switch and a second switch connected in series on a first path connecting the first input terminal and the second input terminal;
a second set of switching devices including a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal;
a resonant capacitor connected between a first node on the first path between the first switch and the second switch and a second node on the second path between the third switch and the fourth switch;
a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor, the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal;
a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal;
a storage unit that stores a data table in which combinations of the input voltage, the input current, the output voltage, and the output current, and combinations of phase target values and operating frequency target values are associated with each other for each target output voltage for the output voltage;
A control circuit,
the control circuit changes a phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and an operating frequency of the first set of switching devices and the second set of switching devices to the phase target value and the operating frequency target value obtained by comparing the sensed input voltage, the input current, the output voltage, and the output current to the data table;
Voltage converter. A method for controlling a voltage converter, comprising the steps of:
The voltage converter includes:
a first set of switching devices including a first switch and a second switch connected in series on a first path connecting the first input terminal and the second input terminal;
a second set of switching devices including a third switch and a fourth switch connected in series on a second path different from the first path connecting the first input terminal and the second input terminal;
a resonant capacitor connected between a first node on the first path between the first switch and the second switch and a second node on the second path between the third switch and the fourth switch;
a transformer having a primary winding and a secondary winding, one end of the primary winding being connected to the resonant capacitor, the other end of the primary winding being connected to the second node, and the secondary winding being connected to a first output terminal and a second output terminal;
a detection circuit that detects an input voltage applied between the first input terminal and the second input terminal, an input current input to the first input terminal, an output voltage applied between the first output terminal and the second output terminal, and an output current output from the first output terminal;
a storage unit that stores a data table in which combinations of the input voltage, the input current, the output voltage, and the output current, and combinations of phase target values and operating frequency target values are associated with each other for each target output voltage for the output voltage;
The control method includes:
obtaining the sensed input voltage, the input current, the output voltage and the output current;
changing a phase between the switching of the first set of switching devices and the switching of the second set of switching devices, and an operating frequency of the first set of switching devices and the second set of switching devices to the phase target value and the operating frequency target value obtained by comparing the sensed input voltage, the input current, the output voltage, and the output current to the data table;
Control methods.

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