JP2013099092A - Power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply apparatus which carries out charge and discharge by using a plurality of batteries, suppresses an efficiency deterioration in the case of charge due to variation in characteristic of each of batteries and can efficiently utilize power of each of batteries in the case of discharge.SOLUTION: A step-up/down circuit 11 is provided so as to correspond to a plurality of capacitors 21, which are provided so as to correspond to batteries 12, connected in parallel to each other, and are connected in series. The step-up/down circuit 11 can carry out charge operation for stepping up or down and outputting a received DC voltage to a corresponding battery 12 and discharge operation for stepping up or down and outputting the DC voltage received from the corresponding battery 12, and also can adjust an output voltage in each of these operations. A circuit at the battery 12 side is electrically insulated from a circuit at the capacitor 21 side.

Description

  The present invention relates to a power supply device, and more particularly to a power supply device that includes a plurality of batteries and charges and discharges these batteries.

  A power storage system that stores power using a rechargeable secondary battery and supplies power to the system from the secondary battery when necessary has been developed (for example, Mitsubishi Heavy Industries Technical Report Vol. 41, No. 5, “Development of lithium ion battery power storage system”, September 2004 (Non-patent Document 1)).

  Such power storage systems include power generation facilities that use power generation methods with large fluctuations in power generation, such as solar power generation and wind power generation, in addition to applications that increase the utilization rate of power generation facilities by reducing fluctuations in power demand. It can be applied to supplementary uses (see, for example, Journal of the Institute of Electrical Installation, October 2005, “Application of Redox Flow Battery to Wind Power Generation Smoothing Use” (Non-Patent Document 2)).

  The power supply device used for such an application includes, for example, an assembly of a plurality of batteries. When the secondary battery is a lithium ion battery, for example, the voltage of one battery is, for example, about 3 V to 4 V, and therefore a plurality of batteries are connected in series. By charging the batteries connected in series, power can be supplied when necessary. That is, electric current flows into the series body of batteries during charging and electric power is stored, and during discharging, current flows out of the series body of batteries and electric power is supplied to the load.

Mitsubishi Heavy Industries Technical Report Vol. 41, no. 5. “Development of lithium-ion battery power storage system”, September 2004 Journal of the Institute of Electrical Installation, October 2005, “Application of Redox Flow Battery to Smooth Wind Power Output”

  By the way, when any one of the batteries in series is charged, if any one of the batteries is fully charged, the charging must be stopped. That is, even if the other battery does not reach the fully charged state, the other battery cannot be further charged.

  In addition, when discharging batteries in series and supplying power to the load, when the battery with the least remaining power reaches the discharge limit, discharging continues even if the remaining battery capacity is sufficient. I can't do it.

  In this way, in the power supply device using the series body of batteries, due to variations in the characteristics of each battery, the charge / discharge performance is constrained by the characteristics of any battery, so each battery cannot be charged sufficiently, In addition, there is a problem that the electric power stored in each battery cannot be effectively used during discharging.

  In order to solve such problems at the time of charging, for example, a configuration in which the charging current is released to another circuit so that the charging current is not supplied to the fully charged battery can be considered. However, with such a configuration, the charging efficiency is reduced due to the occurrence of loss, and the above-described problems during discharging cannot be solved.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to charge and discharge using a plurality of batteries, to suppress a reduction in efficiency during charging due to variations in characteristics of each battery, and It is an object of the present invention to provide a power supply device capable of effectively utilizing the power of each battery during discharging.

  In order to solve the above-described problem, a power supply apparatus according to an aspect of the present invention includes a plurality of batteries connected in parallel to each other, a plurality of capacitors connected in series corresponding to the batteries, and the capacitors A plurality of step-up / step-down circuits provided corresponding to the charging circuit, wherein the step-up / step-down circuit boosts or steps down a DC voltage received from the corresponding capacitor and outputs the boosted voltage to the corresponding battery. A discharge operation in which the DC voltage received from the battery is stepped up or down and output to the corresponding capacitor is possible, the output voltage in the charge operation and the output voltage in the discharge operation can be adjusted, and the battery side The circuit and the circuit on the capacitor side are electrically insulated, and received at both ends of the plurality of capacitors connected in series in the charging operation. The divided voltage of the flow voltage is applied to each said buck circuit, in the discharge operation, the combined voltage of the output voltage of each of the buck-boost circuits is output from the opposite ends.

  With such a configuration, even when there is variation in the characteristics of each battery, it is possible to prevent the charging or discharging from being restricted due to the characteristics of a specific battery. That is, each battery can be fully charged, and the electric power stored in each battery can be effectively utilized during discharging. Furthermore, it is not necessary to release the charging current to another circuit so that the charging current is not supplied to the fully charged battery, and it is possible to prevent a reduction in charging efficiency due to the occurrence of loss. Therefore, it is possible to charge and discharge using a plurality of batteries, suppress a reduction in efficiency during charging due to variations in characteristics of each battery, and to effectively use the power of each battery during discharging. Moreover, each battery can be connected in parallel by the structure which electrically insulates the circuit by the side of a battery and the circuit by the side of a capacitor. This eliminates the need to provide a voltage measurement unit for each battery and separately monitor the voltage of each battery. For example, the configuration and processing can be simplified by sharing the voltage measurement unit and the control unit. Can do.

  Preferably, the power supply device further controls a voltage measuring unit for measuring a voltage of each battery, and controls each step-up / down circuit based on the voltage of each battery measured by the voltage measuring unit. And a control unit for adjusting the output voltage of each of the step-up / down circuits.

  Thus, by simplifying the voltage measuring unit and the control unit for each battery, the configuration and processing can be simplified.

  More preferably, in the charging operation, the control unit controls the step-up / step-down circuits so that the voltages of the batteries reach a target value based on the measurement result of the voltage measurement unit.

  With such a configuration, the voltage of each battery can be uniformly changed based on the measurement result of the common voltage measurement unit, and thus the charging efficiency can be improved.

  More preferably, in the discharge operation, the control unit discharges the batteries by controlling the step-up / down circuits based on the measurement result of the voltage measurement unit, and the voltage of each of the batteries is a lower limit. When the value is reached, the discharge is stopped.

  With such a configuration, the voltage of each battery can be uniformly changed based on the measurement result of the common voltage measurement unit, so that the discharge efficiency can be improved.

  Preferably, the step-up / step-down circuit includes a capacitor connected in parallel to the corresponding battery.

  With such a configuration, the battery can be stabilized and charging and discharging operations can be performed more favorably.

  Preferably, the capacitor has a first end and a second end, and the step-up / down circuit is electrically connected to a transformer including a primary winding and a secondary winding and to the first end of the capacitor. A first switch having a first end and a second end electrically connected to the first end of the primary winding, and electrically connected to the first end of the secondary winding. A second switch having a first end and a second end; a first end electrically connected to the second end of the second switch; and a first end electrically connected to the first end of the battery. An inductor having a second end, a first end electrically connected to a second end of the second switch, a second end of the secondary winding, and a second end of the battery. A third switch having a second end connected to the capacitor, wherein the second end of the capacitor and the second end of the primary winding are electrically connected. To have.

  With such a configuration, a step-up / step-down circuit in which the battery side circuit and the capacitor side circuit are insulated can be realized with a simple configuration.

  Preferably, the power supply device is further connected between both ends of the plurality of capacitors connected in series. In the charging operation, the received AC voltage is converted into a DC voltage and output to both ends of the plurality of capacitors. In the discharging operation, a voltage conversion circuit is provided for converting a DC voltage received from both ends of the plurality of capacitors into an AC voltage and outputting the AC voltage to a load.

  With such a configuration, for example, an AC voltage supplied from an AC power source can be converted to a DC voltage to charge each battery, and an output voltage of each battery can be converted to an AC voltage and supplied to a load.

  According to the present invention, it is possible to charge and discharge using a plurality of batteries, to suppress a decrease in efficiency during charging due to variations in characteristics of each battery, and to effectively use the power of each battery during discharging. .

It is a figure which shows the example of a connection in the structure of the power supply device which concerns on embodiment of this invention, and charging operation. It is a figure which shows the connection example in the structure of the power supply device which concerns on embodiment of this invention, and discharge operation. It is a figure which shows an example of the charging operation by the power supply device which concerns on embodiment of this invention. It is a figure which shows an example of the discharge operation | movement by the power supply device which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram showing a configuration of a power supply device according to an embodiment of the present invention and a connection example in a charging operation. FIG. 2 is a diagram showing a configuration of the power supply device according to the embodiment of the present invention and a connection example in the discharging operation.

  Referring to FIGS. 1 and 2, power supply device 101 includes a plurality of sets of capacitor 21, buck-boost circuit 11, and battery 12, and further includes voltage measurement unit 13, control unit 14, and AC / DC converter (voltage Conversion circuit) 15 and a voltage measurement unit 16. The step-up / down circuit 11 includes a capacitor 27, switches 22, 23 and 24, a transformer 25, and an inductor 26. The transformer 25 includes a primary winding 31 and a secondary winding 32. The switches 22, 23, and 24 are semiconductor elements such as transistors, for example. Thereby, high-speed switching becomes possible. The voltage measuring unit 13 and the control unit 14 may be provided for each group.

  As the battery 12, for example, a lithium ion battery, a nickel metal hydride battery, a lead storage battery, and various other rechargeable batteries can be used.

  In FIG. 1, an AC power supply 201 supplies an AC voltage having an amplitude of 100 V and a frequency of 50 Hz or 60 Hz to the power supply apparatus 101, for example.

  Then, the power supply apparatus 101 charges each set of batteries 12 based on the AC voltage supplied from the AC power supply 201.

  In FIG. 2, the power supply device 101 supplies an AC voltage having an amplitude of 100 V and a frequency of 50 Hz or 60 Hz to the load 202 by discharging each set of batteries 12.

  More specifically, in the power supply apparatus 101, the capacitors 21 are connected in series. Each battery 12 is connected in parallel with each other. The AC / DC converter 15 is connected between both ends of a plurality of capacitors 21 connected in series.

  In the charging operation, the AC / DC converter 15 converts the AC voltage received from the AC power source 201 into a DC voltage, and outputs it to both ends of the plurality of capacitors 21 connected in series. In the discharging operation, the AC / DC converter 15 converts the DC voltage received from both ends of the plurality of capacitors 21 connected in series into an AC voltage and outputs the AC voltage to the load 202.

  In the step-up / step-down circuit 11, the switch 22 has a first end electrically connected to the first end of the capacitor 21 and a second end electrically connected to the first end of the primary winding 31. . Switch 23 has a first end electrically connected to a first end of secondary winding 32, and a second end. Inductor 26 has a first end electrically connected to the second end of switch 23 and a second end electrically connected to the first end of battery 12. The switch 24 includes a first end electrically connected to the second end of the switch 23, and a second end electrically connected to the second end of the secondary winding 32 and the second end of the battery 12. Have. The second end of the capacitor 21 and the second end of the primary winding 31 are electrically connected.

  The capacitor 27 is connected in parallel with the battery 12 in order to stabilize the battery 12.

  The step-up / step-down circuit 11 is capable of bidirectional operation. More specifically, the step-up / step-down circuit 11 boosts or lowers the DC voltage received from the AC / DC converter 15 via the corresponding capacitor 21 and outputs it to the corresponding battery 12, and receives from the corresponding battery 12. It is possible to perform a discharging operation in which the DC voltage is stepped up or stepped down and output to the AC / DC converter 15 via the corresponding capacitor 21. In the step-up / down circuit 11, the output voltage in the charging operation and the output voltage in the discharging operation can be adjusted. In the step-up / step-down circuit 11, the circuit on the battery 12 side and the circuit on the capacitor 21 side are electrically insulated.

  In the charging operation, the divided voltage of the DC voltage received at both ends of the plurality of capacitors 21 connected in series, that is, the divided voltage of the output voltage of the AC / DC converter 15 is applied to each step-up / down circuit 11. In the discharging operation, the combined voltage of the output voltages of the step-up / step-down circuits 11 is output to the AC / DC converter 15 from both ends of the plurality of capacitors 21 connected in series.

  The voltage measurement unit 13 measures the voltage of each set of batteries 12. Since each battery 12 is connected in parallel, in the power supply apparatus 101, one voltage measuring unit 13 may be provided. Moreover, the voltage measurement part 16 measures the voltage between the both ends of the several capacitor 21 connected in series, for example in discharge operation. Instead of the voltage measurement unit 16, a current measurement unit that measures the current flowing through each capacitor 21 may be provided.

  The control unit 14 controls each step-up / down circuit 11 based on the voltage of each battery 12 measured by the voltage measurement unit 13 and the voltage measured by the voltage measurement unit 16, thereby Adjust the output voltage. Specifically, the control unit 14 adjusts the output voltage of each step-up / down circuit 11 by PWM (Pulse Width Modulation) control of each switch in each step-up / down circuit 11.

  More specifically, control unit 14 supplies current corresponding to the current from AC / DC converter 15 to inductor 26 by turning on switch 22 and switch 23 and turning off switch 24 in the charging operation. By alternately repeating the operation of storing energy in the inductor 26 and the operation of discharging the energy stored in the inductor 26 to the battery 12 by turning off the switch 22 and the switch 23 and turning on the switch 24, The battery 12 is charged.

  In addition, the controller 14 supplies the current from the battery 12 to the inductor 26 by turning off the switch 22 and the switch 23 and turning on the switch 24 in the discharging operation, and stores energy in the inductor 26. The battery 12 is discharged by alternately repeating the operation of discharging the energy stored in the inductor 26 to the AC / DC converter 15 by turning on the switch 22 and the switch 23 and turning off the switch 24.

  In these charging operation and discharging operation, the control unit 14 controls the step-up / down circuit 11 so that, for example, the voltage across the capacitor 21 and the voltage of the battery 12 are substantially equal.

  Next, a charging operation by the power supply device according to the embodiment of the present invention will be described. Hereinafter, the target value of the battery 12 in the charging operation is set to 4.2V, and the voltage before charging of the battery 12 in the charging operation is set to 3.0V.

  FIG. 3 is a diagram showing an example of the charging operation by the power supply device according to the embodiment of the present invention.

  Referring to FIG. 3, control unit 14 controls each step-up / down circuit 11 so that the voltage of each battery 12 reaches a target value based on the measurement result of voltage measurement unit 13 in the charging operation.

  More specifically, the control unit 14 starts charging each battery 12 at the timing t1. Here, the control unit 14 controls each switch in each step-up / down circuit 11 while referring to the measurement result of the voltage measurement unit 13. Since each battery 12 is connected in parallel, the voltage of each battery 12 rises uniformly.

  Then, when the voltage of each battery 12 reaches the target value at timing t2, the control unit 14 turns off each switch in each step-up / down circuit 11 and ends the charging operation.

  Next, the discharge operation by the power supply device according to the embodiment of the present invention will be described. Hereinafter, the voltage before discharging of the battery 12 in the discharging operation is set to 4.2V, and the lower limit value of the battery 12, that is, the voltage value at which the discharging operation should be stopped is set to 3.0V.

  FIG. 4 is a diagram showing an example of a discharge operation by the power supply device according to the embodiment of the present invention.

  Referring to FIG. 4, control unit 14 discharges each battery 12 by controlling each step-up / down circuit 11 based on the measurement result of voltage measurement unit 13 in the discharge operation. And the control part 14 will stop discharge, if the voltage of each battery 12 reaches a lower limit.

  More specifically, the control unit 14 starts discharging each battery 12 at timing t21. The control unit 14 controls each step-up / down circuit 11 so that the voltage measured by the voltage measurement unit 16 maintains a predetermined value, for example, so that the level of the voltage supplied to the load 202 is constant.

  Here, the control unit 14 controls each switch in each step-up / down circuit 11 while referring to the measurement result of the voltage measurement unit 13. Since each battery 12 is connected in parallel, the voltage of each battery 12 falls uniformly.

  Then, when the voltage of each battery 12 reaches the lower limit value at timing t22, the control unit 14 turns off each switch in each step-up / down circuit 11 and ends the discharging operation.

  By the way, in the power supply device using the series body of the batteries, the charge / discharge performance is constrained by the characteristics of one of the batteries due to variations in the characteristics of each battery, so that each battery cannot be charged sufficiently. There is a problem that the electric power stored in each battery cannot be effectively used during discharging. In order to solve such problems at the time of charging, for example, a configuration in which the charging current is released to another circuit so that the charging current is not supplied to the fully charged battery can be considered. However, with such a configuration, the charging efficiency is reduced due to the occurrence of loss, and the above-described problems during discharging cannot be solved.

  On the other hand, in the power supply device according to the embodiment of the present invention, the batteries 12 are connected in parallel to each other. A plurality of capacitors 21 are provided corresponding to the battery 12, and each capacitor 21 is connected in series. In the step-up / step-down circuit 11, the circuit on the battery 12 side and the circuit on the capacitor 21 side are electrically insulated. The step-up / step-down circuit 11 is provided corresponding to the capacitor 21 and boosts or steps down the DC voltage received from the corresponding capacitor 21 and outputs it to the corresponding battery 12, and the DC voltage received from the corresponding battery 12. Can be discharged or boosted and output to the corresponding capacitor 21, and the output voltage in the charging operation and the output voltage in the discharging operation can be adjusted. In the charging operation, the divided voltage of the DC voltage received at both ends of the plurality of capacitors 21 connected in series is supplied to each step-up / down circuit 11. Further, in the discharging operation, a combined voltage of the output voltages of each step-up / down circuit 11 is output from both ends of the plurality of capacitors 21 connected in series.

  With such a configuration, even when there is variation in the characteristics of each battery, it is possible to prevent the charging or discharging from being restricted due to the characteristics of a specific battery. That is, each battery can be fully charged, and the electric power stored in each battery can be effectively utilized during discharging. Furthermore, it is not necessary to release the charging current to another circuit so that the charging current is not supplied to the fully charged battery, and it is possible to prevent a reduction in charging efficiency due to the occurrence of loss.

  Therefore, in the power supply device according to the embodiment of the present invention, charging / discharging is performed using a plurality of batteries, and a reduction in efficiency during charging due to variation in characteristics of each battery is suppressed, and power of each battery during discharging is reduced. Can be used effectively.

  Moreover, each battery can be connected in parallel by the structure which electrically insulates the circuit by the side of a battery and the circuit by the side of a capacitor. This eliminates the need to provide a voltage measurement unit for each battery and separately monitor the voltage of each battery. For example, the configuration and processing can be simplified by sharing the voltage measurement unit and the control unit. Can do.

  Moreover, in the power supply device according to the embodiment of the present invention, the voltage measurement unit 13 measures the voltage of each battery 12. The control unit 14 adjusts the output voltage of each step-up / down circuit 11 by controlling each step-up / down circuit 11 based on the voltage of each battery 12 measured by the voltage measurement unit 13.

  Thus, by sharing the voltage measuring unit 13 and the control unit 14 for each battery 12, the configuration and processing can be simplified.

  Further, in the power supply device according to the embodiment of the present invention, the control unit 14 is configured to increase or decrease each voltage so that the voltage of each battery 12 reaches a common target value based on the measurement result of the voltage measurement unit 13 in the charging operation. The pressure circuit 11 is controlled.

  With such a configuration, the voltage of each battery 12 can be uniformly changed based on the measurement result of the common voltage measurement unit 13, so that charging efficiency can be improved.

  In the power supply device according to the embodiment of the present invention, the control unit 14 discharges each battery 12 by controlling each step-up / down circuit 11 based on the measurement result of the voltage measurement unit 13 in the discharge operation. To do. And the control part 14 will stop discharge, if the voltage of each battery 12 reaches a common lower limit.

  With such a configuration, the voltage of each battery can be changed uniformly based on the measurement result of the common voltage measurement unit 13, so that the discharge efficiency can be improved.

  Further, in the power supply device according to the embodiment of the present invention, the step-up / step-down circuit 11 includes a capacitor 27 connected in parallel to the corresponding battery 12.

  With such a configuration, the battery 12 can be stabilized and the charging operation and the discharging operation can be performed better.

  In the power supply apparatus according to the embodiment of the present invention, in the step-up / step-down circuit 11, the switch 22 includes a first end electrically connected to the first end of the capacitor 21 and a first end of the primary winding 31. And a second end electrically connected to the end. Switch 23 has a first end electrically connected to a first end of secondary winding 32, and a second end. Inductor 26 has a first end electrically connected to the second end of switch 23 and a second end electrically connected to the first end of battery 12. The switch 24 includes a first end electrically connected to the second end of the switch 23, and a second end electrically connected to the second end of the secondary winding 32 and the second end of the battery 12. Have. The second end of the capacitor 21 and the second end of the primary winding 31 are electrically connected.

  With such a configuration, a step-up / step-down circuit in which the battery side circuit and the capacitor side circuit are insulated can be realized with a simple configuration.

  In the power supply device according to the embodiment of the present invention, the AC / DC converter 15 is connected between both ends of a plurality of capacitors 21 connected in series. The AC / DC converter 15 converts the received AC voltage into a DC voltage in the charging operation and outputs it to both ends of the plurality of capacitors 21, and the DC voltage received from the both ends of the plurality of capacitors 21 in the discharging operation And output to the load 202.

  With such a configuration, the AC voltage supplied from the AC power supply 201 is converted to a DC voltage to charge each battery 12, and the output voltage of each battery 12 is converted to an AC voltage and supplied to the load 202. Can do.

  In addition, although the power supply device which concerns on embodiment of this invention was set as the structure provided with the voltage measurement part 13 and the control part 14, it is not limited to this. The voltage measurement unit 13 and the control unit 14 may be provided outside the power supply device 101.

  Moreover, although the power supply device which concerns on embodiment of this invention was set as the structure provided with the AC / DC converter 15, it is not limited to this. Even when the AC / DC converter 15 is not provided, each battery 12 can be charged based on a DC voltage supplied from the outside, and each battery 12 can be discharged to supply a DC voltage to the outside. is there.

  In the power supply device according to the embodiment of the present invention, the voltage of the battery 12 is a positive voltage. However, the present invention is not limited to this, and the voltage of the battery 12 may be a negative voltage.

  Moreover, in the power supply device according to the embodiment of the present invention, the “inductor” includes a large component such as a reactor.

  The above embodiment should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 11 Buck-boost circuit 12 Battery 13 Voltage measurement part 14 Control part 15 AC / DC converter (voltage conversion circuit)
16 Voltage measuring unit 21, 27 Capacitor 22, 23, 24 Switch 25 Transformer 26 Inductor 31 Primary winding 32 Secondary winding 101 Power supply

Claims (7)

A plurality of batteries connected in parallel to each other;
A plurality of capacitors provided corresponding to the battery and connected in series;
A plurality of step-up / step-down circuits provided corresponding to the capacitors,
The step-up / step-down circuit boosts or steps down the DC voltage received from the corresponding capacitor and outputs the boosted voltage to the corresponding battery, and boosts or steps down the DC voltage received from the corresponding battery. The discharge operation to output to the capacitor is possible, the output voltage in the charge operation and the output voltage in the discharge operation can be adjusted, and the circuit on the battery side and the circuit on the capacitor side are electrically insulated ,
In the charging operation, a divided voltage of a DC voltage received at both ends of the plurality of capacitors connected in series is given to each of the step-up / down circuits.
In the discharging operation, a power supply device in which a combined voltage of output voltages of the step-up / step-down circuits is output from both ends. The power supply device further includes:
A voltage measuring unit for measuring the voltage of each of the batteries;
The control unit for adjusting the output voltage of each step-up / down circuit by controlling each step-up / down circuit based on the voltage of each battery measured by the voltage measuring unit. The power supply described.   3. The power supply device according to claim 2, wherein, in the charging operation, the control unit controls each of the step-up / step-down circuits so that the voltage of each battery reaches a target value based on a measurement result of the voltage measurement unit. .   In the discharging operation, the control unit discharges each battery by controlling each step-up / down circuit based on the measurement result of the voltage measuring unit, and the voltage of each battery reaches a lower limit value. The power supply device according to claim 2, wherein the discharge is stopped.   5. The power supply device according to claim 1, wherein the step-up / step-down circuit includes a capacitor connected in parallel to the corresponding battery. 6. The capacitor has a first end and a second end;
The step-up / down circuit is
A transformer including a primary winding and a secondary winding;
A first switch having a first end electrically connected to the first end of the capacitor and a second end electrically connected to the first end of the primary winding;
A second switch having a first end electrically connected to the first end of the secondary winding and a second end;
An inductor having a first end electrically connected to a second end of the second switch and a second end electrically connected to the first end of the battery;
A first end electrically connected to a second end of the second switch; and a second end electrically connected to a second end of the secondary winding and a second end of the battery. A third switch,
The power supply device according to any one of claims 1 to 5, wherein a second end of the capacitor and a second end of the primary winding are electrically connected. The power supply device further includes:
Connected between both ends of the plurality of capacitors connected in series. In the charging operation, the received AC voltage is converted into a DC voltage and output to both ends of the plurality of capacitors. In the discharging operation, the plurality of capacitors. The power supply device according to any one of claims 1 to 6, further comprising a voltage conversion circuit for converting a DC voltage received from both ends into an AC voltage and outputting the AC voltage to a load.

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