JP2014057387A - Power conversion circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion circuit which, although designed to transform voltage bidirectionally between a power supply and a mobile unit incorporating a secondary battery, can restrain a reduction in the efficiency of the power system.SOLUTION: Provided is a power conversion circuit having a first terminal connected to a power supply and a second terminal connected to a mobile unit incorporating a secondary battery and designed to transform voltage bidirectionally between the first and the second terminals, wherein a chopper circuit for transforming voltage by a chopping operation and a transformer having a prescribed transformation ratio are provided in series between the first and the second terminals. For voltage transformation from the first terminal to the second terminal, the chopping operation is not performed, and voltage transformation using the transformer is performed; for voltage transformation from the second terminal to the first terminal, the chopping operation is performed, and voltage transformation using the transformer and the chopper circuit is performed.

Description

  The present invention relates to a power conversion circuit that performs bidirectional transformation.

  Conventionally, various types of mobile bodies equipped with secondary batteries have been developed, and EV (Electric Vehicle) is a typical example. EV has various advantages and is expected to spread widely to various businesses and households.

  Generally, a power source (electric power system or the like) that supplies electric power to a household load is used to charge the EV in each home. In this case, when charging, power is transmitted from the power source to the EV. At this time, transformation is performed to optimize the charging voltage of the secondary battery.

  For example, it has been proposed to use an EV secondary battery as an external power source for household loads in an emergency such as an earthquake disaster. When the EV secondary battery is used as an external power supply in this way, the discharge power of the secondary battery is transmitted toward the household load. At this time, transformation is performed to optimize the supply voltage to the household load.

  FIG. 6 is a configuration example of a power system that enables charging and discharging in the above-described form. As shown in the figure, the electric power system is provided with a charger / discharger 101 for charging and discharging the secondary battery. The charger / discharger 101 has one end connected to the power system E and the household load LD via the DC / AC converter 104, and the other end connected to the EV 106 equipped with a secondary battery.

  The charger / discharger 101 is provided with a power conversion circuit that performs bidirectional transformation. The power conversion circuit performs a transformation operation for optimizing the charging voltage when charging the secondary battery, and performs a transformation operation for optimizing the supply voltage to the home load LD when discharging the secondary battery. .

JP 2011-200012 A JP 2009-177940 A

  Since the use of a moving body such as EV is basically a moving means, the secondary battery mounted thereon is mainly used as a driving power source for the moving body. Under such circumstances, when comparing the frequency of charging and the frequency of discharging in the secondary battery of the mobile body, the frequency of charging is expected to be overwhelmingly higher. Therefore, about the charger / discharger (power conversion circuit) of the example mentioned above, the one where the efficiency is improved at the time of charging than when the secondary battery is discharged can efficiently use the power system.

  As a configuration example of the above-described power conversion circuit, a configuration in which a circuit that performs bidirectional transformation using a transformer and a chopper circuit that performs bidirectional transformation is provided and a circuit that performs transformation is provided in two stages is considered. It is done. According to such a two-stage circuit configuration, since a chopper circuit is provided, it is possible to cope with a voltage that cannot be boosted or lowered only by a transformer whose transformation ratio is determined by the ratio of the number of windings. Also, by using a transformer, it is possible to insulate the EV side from the home power system side and ensure safety.

  However, the two-stage circuit configuration results in lower power efficiency than the one-stage circuit configuration. For example, compared to a one-stage circuit configuration having a circuit that performs bidirectional transformation using a transformer, the above-described two-stage circuit configuration has a power efficiency that is equivalent to the transformation operation (chopping operation) of the chopper circuit. descend. Therefore, when a charger / discharger having a two-stage circuit configuration is used, there is a problem that the efficiency of the power system is lowered.

  In view of the above-described problems, the present invention provides a power conversion circuit capable of suppressing a reduction in efficiency of a power system while performing bidirectional transformation between a power source and a mobile body equipped with a secondary battery. For the purpose of provision.

  A power conversion circuit according to the present invention has a first end connected to a power source and a second end connected to a mobile body equipped with a secondary battery, and is bidirectional between the first end and the second end. A power conversion circuit that performs voltage transformation in a chopper circuit that performs voltage transformation by a chopping operation and a transformer having a predetermined voltage transformation ratio are provided in series between the first end and the second end, and from the first end When performing transformation to the second end, the chopping operation is not performed, the transformation using the transformer is performed, and during the transformation from the second end to the first end, the chopping operation is performed, and the transformer and the It is configured to perform voltage transformation using a chopper circuit.

  According to this configuration, it is possible to suppress a reduction in the efficiency of the power system while performing bidirectional transformation between the power source and the mobile body equipped with the secondary battery. The specific form of connection between the power source and the first end is not particularly limited, and for example, either direct connection or indirect connection may be used. In addition, the specific form of connection between the mobile body on which the secondary battery is mounted and the second end is not particularly limited, and for example, either direct connection or indirect connection may be used.

  More specifically, the bidirectional transformer circuit including the chopper circuit and the transformer is provided in series between the first end and the second end, and the bidirectional transformer circuit, An operation of converting a DC voltage input to one end into AC, transforming the converted voltage using the transformer, converting the transformed voltage into a DC voltage, and outputting the voltage from the other end in both directions. It is good also as a structure to perform.

  More specifically, as the above configuration, the chopper circuit may be a boost type chopper circuit that performs boosting in the direction from the second end to the first end by the chopping operation.

  More specifically, in the above configuration, the transformer transformation ratio may be set based on the difference between the voltage value of the power source and the voltage value allowed for charging the secondary battery. .

  More specifically, the above configuration may include a control circuit that controls operations of the chopper circuit and the bidirectional transformer circuit, and the driving power of the control circuit may be supplied from the secondary battery. .

  More specifically, the mobile unit may be an electric vehicle that is driven using electric power stored in the secondary battery.

  According to the power conversion circuit of the present invention, it is possible to suppress a reduction in the efficiency of the power system while performing bidirectional transformation between the power source and the mobile body equipped with the secondary battery.

It is a lineblock diagram of an electric power system concerning an embodiment of the present invention. It is a block diagram of the charger / discharger and its periphery which concern on embodiment of this invention. 1 is a configuration diagram of a two-stage transformer circuit according to an embodiment of the present invention. It is explanatory drawing regarding the operation | movement form of the power converter circuit at the time of charge. It is explanatory drawing regarding the operation | movement form of the power converter circuit at the time of discharge. It is a block diagram of the electric power system which concerns on a prior art example.

[Power system configuration]
The power system according to the embodiment of the present invention will be described below. FIG. 1 is a configuration diagram of the power system 9. As shown in the figure, the power system 9 includes a charger / discharger 1, a PV-DC / DC converter 2, a BAT-DC / DC converter 3, a DC / AC converter 4, a charging port 5, EV6, and a solar cell PV. , Storage battery BAT, electric power system E, and load LD.

  The charger / discharger 1 has a function of performing bidirectional transformation, so that the secondary battery mounted on the EV 6 is appropriately charged / discharged. A more detailed configuration of the charger / discharger 1 will be described again. One end of the charger / discharger 1 is connected to a DC line Ln used for transmission of DC power, and the other end of the charger / discharger 1 is connected to the charging port 5.

  The PV-DC / DC converter 2 has one end connected to the solar cell PV and the other end connected to the DC line Ln, and plays a role of transforming DC power obtained by power generation of the solar cell PV. The DC power transformed by the PV-DC / DC converter 2 is sent to the DC line Ln.

  The BAT-DC / DC converter 3 has one end connected to the storage battery BAT and the other end connected to the DC line Ln, and plays a role of transforming the charging power and discharging power of the storage battery BAT. That is, the BAT-DC / DC converter 3 transforms the DC power received from the DC line Ln and sends it to the storage battery BAT when the storage battery BAT is charged. The BAT-DC / DC converter 3 transforms the DC power received from the storage battery BAT when the storage battery BAT is discharged, and sends it to the DC line Ln.

  The DC / AC converter 4 has one end connected to the DC line Ln and the other end connected to the power system E and the load LD. The DC / AC converter 4 converts the direct current power received from the direct current line Ln into alternating current and sends it to the load LD, and converts the alternating current power received from the power system E into direct current and sends it to the direct current line Ln. Play a role.

  The load LD is, for example, a household load (such as a home appliance), and the power system E supplies power to the load LD. The electric power system E is also used as a power source for supplying charging power to the EV6 secondary battery.

  The charging port 5 is detachably attached to the EV 6 and serves as an interface between the charger / discharger 1 and the EV 6. The EV 6 is a moving body on which, for example, a 12V secondary battery is mounted, and is driven using electric power stored in the secondary battery. When the EV 6 is connected to the charging port 5, the secondary battery of the EV 6 is connected to the charger / discharger 1.

[Configuration of charger / discharger]
Next, the configuration of the charger / discharger 1 will be described in more detail. FIG. 2 is a configuration diagram of the charger / discharger 1 and its surroundings.

  As shown in the figure, the charger / discharger 1 includes an EMI filter circuit 11, a filter circuit 12, a two-stage transformer circuit 13, an EMI filter circuit 14, an earth leakage circuit breaker 15, a ground fault detection circuit 16, a control circuit 17, and a sequence circuit. 18 and an auxiliary power source 19 and the like.

  One end of the charger / discharger 1 (side connected to the DC line Ln) is connected to the first terminal T1 which is one end of the two-stage transformer circuit 13 through the EMI filter circuit 11 and the filter circuit 12 in this order. The second terminal T2 which is the other end of the two-stage transformer circuit 13 is connected to the other end (the side connected to the charging port 5) of the charger / discharger 1 through the EMI filter circuit 14 and the leakage breaker 15 in this order. ing.

  Each EMI filter circuit (11, 14) is a filter that removes noise (electromagnetic interference) given to the surroundings by the power transmitted in the charger / discharger 1. The filter circuit 12 includes an electrolytic capacitor and an inductor, and is a filter that removes noise included in the power transmitted in the charger / discharger 1.

  The earth leakage circuit breaker 15 [ELCB (Earth Leakage Circuit Breaker)] plays a role of ensuring safety by automatically breaking between both ends when an earth leakage occurs. The ground fault detection circuit 16 detects a ground fault between the EMI filter circuit 14 and the earth leakage breaker 15.

  As will be described later, the two-stage transformer circuit 13 has a two-stage transformer circuit, and performs bidirectional transformation (power conversion) between the first terminal T1 and the second terminal T2. It is possible. The transformation operation of the two-stage transformer circuit 13 is controlled by a control signal supplied from the control circuit 17.

  That is, the two-stage transformer circuit 13 forms a power conversion circuit EC together with the control circuit 17. The power conversion circuit EC performs bidirectional transformation between the first terminal T1 and the second terminal T2. A more specific configuration of the two-stage transformer circuit 13 will be described again.

  The control circuit 17 controls various operations of the charger / discharger 1. The control circuit 17 has a function of performing communication with the charging port 5 and CAN [Controller Area Network] communication with the EV 6. The control circuit 17 also has a function of recognizing an operation of a user interface (not shown) (such as a remote controller) and receiving a user instruction.

  With these functions, the control circuit 17 can determine the connection state of the EV 6 to the charging port 5, the timing for charging or discharging the secondary battery of the EV 6, and the like. For example, the control circuit 17 charges the secondary battery when a charge instruction is given in a situation where the secondary battery can be charged. For example, the control circuit 17 discharges the secondary battery when a discharge instruction is given in a situation where the secondary battery can be discharged.

  The control circuit 17 detects the current value and the voltage value at both ends of the two-stage transformer circuit 13 and controls the two-stage transformer circuit 13 so that the secondary battery of the EV 6 is appropriately charged and discharged. . The sequence circuit 18 performs processing related to a CHAdeMO (registered trademark) charging sequence between the charger / discharger 1 and the EV 6.

  The auxiliary power supply unit 19 serves to supply drive power to the control circuit 17. The auxiliary power supply unit 19 is connected between the EMI filter circuit 11 and the filter circuit 12, and supplies electric power sent from here to the control circuit 17 as drive power in a normal state. Note that the auxiliary power supply unit 19 has a function as a UPS, and can continue to supply drive power to the control circuit 17 in an emergency such as a power failure.

  Further, the auxiliary power supply unit 19 may be connected to the secondary battery of the EV 6 via the charging port 5 and supply the electric power sent from the secondary battery to the control circuit 17 as driving power. In this case, the driving power of the control circuit 17 is supplied from the secondary battery of EV6.

  The charger / discharger 1 outputs the DC power input from the DC line Ln to the charging port 5 through a path including the two-stage transformer circuit 13 and the like when the EV6 secondary battery is charged. The output power is used for charging the EV6 secondary battery.

  In addition, the charger / discharger 1 passes the DC power input from the charging port 5 (secondary battery discharge power) through the path including the two-stage transformer circuit 13 and the like when the secondary battery of the EV 6 is discharged. Output to. This output power is sent to the load LD or the like.

[Configuration of two-stage transformer circuit]
Next, the configuration of the two-stage transformer circuit 13 will be described in more detail. FIG. 3 is a configuration diagram of the two-stage transformer circuit 13.

  As shown in the figure, the two-stage transformer circuit 13 includes a chopper circuit 131 and a bidirectional transformer circuit 132. More specifically, the chopper circuit 131 and the bidirectional transformer circuit 132 are provided in series between the first terminal T1 and the second terminal T2.

  That is, the two-stage transformer circuit 13 has a two-stage circuit configuration including a chopper circuit 131 and a bidirectional transformer circuit 132. The two-stage transformer circuit 13 includes a first terminal T1 connected to the filter circuit 12 and a second terminal T2 connected to the EMI filter circuit 14, and each terminal (T3, T4) connected to the ground point. Is also provided.

  The chopper circuit 131 includes a first switch element Q1, a second switch element Q2, a first diode D1, a second diode D2, a coil L, and a first capacitor C1.

  Note that the type of switch element used in the two-stage transformer circuit 13 is, for example, an IGBT [Insulated Gate Bipolar Transistor], but other types that can be switched on / off (conduction / cutoff) between both ends. It does not matter. The specific form of the diode is not particularly limited, and may be, for example, a built-in diode in a switch element.

  The chopper circuit 131 is a step-up chopper circuit that boosts a voltage input from the first terminal T1 side by a chopping operation and outputs the boosted voltage to the bidirectional transformer circuit 132 side. The chopping operation of the chopper circuit 131 is realized by the switching operation (repeat on / off switching) of the first and second switch elements (Q1, Q2).

  The bidirectional transformer circuit 132 includes third to tenth switch elements (Q3 to Q10), third to tenth diodes (D3 to D10), a second capacitor C2, a third capacitor C3, and a transformer Tr. . The transformer Tr has a first coil Tr1 and a second coil Tr2 that are insulated from each other, and electric power is transmitted between these coils by electromagnetic induction. Further, the transformation ratio of the transformer Tr is determined by the ratio of the number of windings (ratio of the number of windings of the first coil Tr1 and the number of windings of the second coil Tr2).

  The first capacitor C1 has one end connected to the first terminal T1 and the other end connected to the terminal T3. The first switch element Q1 has a collector connected to the first terminal T1, and an emitter connected to one end of the coil L and the collector of the second switch element Q2. The other end of the coil L is connected to one end of the second capacitor C2, the collector of the third switch element Q3, and the collector of the fifth switch element Q5.

  The other end of the second capacitor C2, the emitter of the second switch element Q2, the emitter of the fourth switch element Q4, and the emitter of the sixth switch element Q6 are connected to the terminal T3. The emitter of the third switch element Q3 is connected to the collector of the fourth switch element Q4 and one end of the first coil Tr1. The emitter of the fifth switch element Q5 is connected to the collector of the sixth switch element Q6 and the other end of the first coil Tr1.

  The collector of the seventh switch element Q7, the collector of the ninth switch element Q9, and one end of the third capacitor C3 are connected to the second terminal T2. The emitter of the eighth switch element Q8, the emitter of the tenth switch element Q10, and the other end of the third capacitor C3 are connected to the terminal T4. The emitter of the seventh switch element Q7 is connected to the collector of the eighth switch element Q8 and one end of the second coil Tr2. The emitter of the ninth switch element Q9 is connected to the collector of the tenth switch element Q10 and the other end of the second coil Tr2.

  The nth diode (n is 1 to 10) corresponds to the nth switch element. Each diode (D1 to D10) has an anode connected to the emitter of the corresponding switch element and a cathode connected to the collector of the corresponding switch element. A control signal Sn is input from the control circuit 17 to the gate of the nth switch element. Thereby, the operation of the two-stage transformer circuit 13 (the operation of the chopper circuit 131 and the bidirectional transformer circuit 132) is controlled by the control circuit 17.

[Operation form of power conversion circuit]
The control circuit 17 changes the control form of the two-stage transformer circuit 13 depending on whether the secondary battery of the EV 6 is charged or discharged. Thereby, the operation mode of the power conversion circuit EC changes during charging and discharging. This mode of operation will be described below.

  When the EV6 secondary battery is charged, the control circuit 17 controls the two-stage transformer circuit 13 so that transformation from the first terminal T1 to the second terminal T2 is performed. In addition, by performing the transformation from the first terminal T1 to the second terminal T2, the transformation from the DC line Ln side to the EV6 side is realized when viewed as the charger / discharger 1 as a whole.

  More specifically, the first switch element Q1 is fixed on, the second and seventh to tenth switch elements (Q2, Q7 to Q10) are fixed off, and the third to sixth switch elements (Q3 to Q3) are fixed. The control circuit 17 outputs each control signal (S1 to S10) so that Q6) performs the switching operation.

  FIG. 4 shows an equivalent configuration of the two-stage transformer circuit 13 when the control signals (S1 to S10) are output in this way. According to this configuration, when the third to sixth switch elements (Q3 to Q6) perform the switching operation in the bidirectional transformer circuit 132, the DC voltage input to the first terminal T1 is converted into an AC voltage. This AC voltage is transformed by the transformer Tr and then returned to DC, and is output from the second terminal T2.

  At this time, since the first and second switching elements (Q1, Q2) do not perform the switching operation, the chopping operation by the chopper circuit 131 is not performed. In this way, during the transformation from the first terminal T1 to the second terminal T2, the chopping operation by the chopper circuit 131 is not performed, and the transformation using the transformer Tr is performed. Therefore, power loss accompanying the chopping operation can be suppressed.

  Further, the transformation ratio of the transformer Tr is set so that an appropriate transformation can be realized only by the transformation by the transformer Tr when the transformation is performed from the first terminal T1 to the second terminal T2. For example, the transformation ratio of the transformer Tr is set based on the difference between the voltage value of the electric power system E and the voltage value allowed for charging the secondary battery of the EV6 so that the charging of the secondary battery is not hindered (transformation). The subsequent voltage value is set to be a voltage value allowed for charging the secondary battery. Therefore, even if the chopping operation by the chopper circuit 131 is not performed, the transformation from the first terminal T1 to the second terminal T2 is appropriately performed.

  On the other hand, when discharging the secondary battery of EV6, the control circuit 17 controls the two-stage transformer circuit 13 so that the transformation from the second terminal T2 to the first terminal T1 is performed. In addition, by performing the transformation from the second terminal T2 to the first terminal T1, the transformation from the EV6 side to the DC line Ln side is realized when viewed as the charger / discharger 1 as a whole.

  More specifically, the first and third to sixth switch elements (Q1, Q3 to Q6) are fixed off, and the second and seventh to tenth switch elements (Q2, Q7 to Q10) perform the switching operation. As is done, the control circuit 17 outputs each control signal (S1 to S10).

  FIG. 5 shows an equivalent configuration of the two-stage transformer circuit 13 when the control signals (S1 to S10) are output in this way. According to this configuration, when the seventh to tenth switch elements (Q7 to Q10) perform the switching operation in the bidirectional transformer circuit 132, the DC voltage input to the second terminal T2 is converted into an AC voltage. This AC voltage is transformed by the transformer Tr and then returned to DC, and sent to the chopper circuit 131. This DC voltage is boosted by the chopping operation of the chopper circuit 131, and is output from the first terminal T1 as a DC voltage.

  As described above, during the transformation from the second terminal T2 to the first terminal T1, the chopping operation by the chopper circuit 131 is performed, and the transformation using the transformer Tr and the chopper circuit 131 is performed.

  Therefore, even when there is a difference between the target amount of transformation and the amount of transformation by the transformer Tr in the transformation from the second terminal T2 to the first terminal T1, the amount of transformation by the chopping operation of the chopper circuit 131 is this. Appropriate transformation is realized by setting to cancel the difference. The chopper circuit 131 according to the present embodiment is a step-up type chopper circuit that performs step-up in the direction from the second end T2 toward the first end T1 by a chopping operation. It may be a pressure type.

[Others]
As described above, the power converter circuit EC is formed in the charger / discharger 1. The power conversion circuit EC has a first terminal T1 connected to a power source such as the electric power system E and the like, and a second terminal T2 connected to the EV 6 equipped with a secondary battery. The first terminal T1 and the second terminal T2 Transform in both directions.

  In the power conversion circuit EC, a chopper circuit 131 for performing transformation by a chopping operation and a transformer Tr having a predetermined transformation ratio are provided in series between the first terminal T1 and the second terminal T2, and the first terminal T1. In the transformation from the second terminal T2 to the second terminal T2, the chopping operation is not performed, the transformation using the transformer Tr is performed, and in the transformation from the second terminal T2 to the first terminal T1, the chopping operation is performed, Transformation is performed using the transformer Tr and the chopper circuit 131.

  Therefore, according to the power conversion circuit EC, it is possible to suppress a decrease in efficiency of the power system 9 while performing bidirectional transformation between the power source of the power system E and the like and the EV 6 equipped with the secondary battery. It has become.

  That is, according to the power conversion circuit EC, when the secondary battery is discharged, the chopping operation by the chopper circuit 131 is performed for adjusting the amount of transformation, but when the secondary battery is charged, the chopping operation is performed. No action is taken. Therefore, according to the power conversion circuit EC, the power loss due to the chopping operation can be suppressed during the charging of the secondary battery, and the power conversion efficiency is good.

  Since the use of a moving body such as EV is basically a moving means, the secondary battery mounted on the moving body is mainly used as a driving power source for the moving body. Under such circumstances, when comparing the frequency of charging and the frequency of discharging in the secondary battery of the mobile body, the frequency of charging is expected to be overwhelmingly higher. Therefore, according to the power conversion circuit EC having good power conversion efficiency during charging, a decrease in efficiency of the power system 9 can be suppressed.

  In the power conversion circuit EC, a chopper circuit 131 and a bidirectional transformer circuit 132 including a transformer Tr are provided in series between the first terminal T1 and the second terminal T2. The bidirectional transformer circuit 132 converts a DC voltage input to one end into an AC, transforms the converted voltage using a transformer Tr, converts the transformed voltage into a DC voltage, and outputs it from the other end. The operation to be performed is bidirectional.

  The configuration of the present invention can be variously modified in addition to the above embodiment without departing from the spirit of the invention. That is, the above-described embodiment is an example in all respects, and should be considered not restrictive. The technical scope of the present invention is shown not by the above description of the embodiment but by the scope of the claims, and is understood to include all modifications within the meaning and scope equivalent to the scope of the claims. Should.

  The present invention can be used for a power system to which an EV is connected.

DESCRIPTION OF SYMBOLS 1 Charger / Discharger 11 EMI filter circuit 12 Filter circuit 13 Two-stage transformer circuit 131 Chopper circuit 132 Bidirectional transformer circuit 14 EMI filter circuit 15 Earth leakage breaker 16 Ground fault detection circuit 17 Control circuit 18 Sequence circuit 19 Auxiliary power supply unit 2 PV -DC / DC converter 3 BAT-DC / DC converter 4 DC / AC converter 5 Charging port 6 EV (mobile body equipped with a secondary battery)
BAT Storage battery E Power system EC Power conversion circuit LD Load PV Solar cell T1 First terminal (first terminal)
T2 Second terminal (second end)
T3, T4 terminals L coil Tr transformer Tr1 first coil Tr2 second coil C1 to C3 capacitors Q1 to Q10 switching elements D1 to D10 diodes

Claims (6)

A power conversion circuit that has a first end connected to a power source and a second end connected to a mobile body equipped with a secondary battery, and performs bidirectional transformation between the first end and the second end. And
A chopper circuit for performing transformation by a chopping operation, and a transformer having a predetermined transformation ratio are provided in series between the first end and the second end,
During the transformation from the first end to the second end, the chopping operation is not performed, the transformation using the transformer is performed,
A power conversion circuit that performs the chopping operation during the transformation from the second end to the first end, and performs transformation using the transformer and the chopper circuit. The bidirectional circuit including the chopper circuit and the transformer is provided in series between the first end and the second end,
The bidirectional transformer circuit is:
An operation of converting a DC voltage input to one end into AC, transforming the converted voltage using the transformer, converting the transformed voltage into a DC voltage, and outputting the voltage from the other end in both directions. The power conversion circuit according to claim 1, wherein the power conversion circuit is performed. The chopper circuit is
The power conversion circuit according to claim 2, wherein the power conversion circuit is a step-up chopper circuit that performs step-up in a direction from the second end toward the first end by the chopping operation. The transformer transformation ratio is:
The power conversion circuit according to claim 3, wherein the power conversion circuit is set based on a difference between a voltage value of the power source and a voltage value allowed for charging the secondary battery. A control circuit for controlling operations of the chopper circuit and the bidirectional transformer circuit;
5. The power conversion circuit according to claim 2, wherein driving power of the control circuit is supplied from the secondary battery. 6. The moving body is
The power conversion circuit according to any one of claims 1 to 5, wherein the power conversion circuit is an electric vehicle that is driven by using electric power stored in the secondary battery.

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