Power conversion device

Abstract

This power conversion device comprises: a first power conversion circuit that converts output power from a storage battery into power to be output to a power supply port; a second power conversion circuit that converts input power from a charging port into power to be supplied to the storage battery; and a switching circuit that can switch to either a conductive state or a cut-off state. The first power conversion circuit includes: a first transformer having a primary winding connected to the storage battery side and a secondary winding connected to the power supply port side; and a bridge circuit connected between the secondary winding and the power supply port. The second power conversion circuit includes a second transformer having a first winding connected to the charging port side, a second winding connected to the storage battery side, and a third winding connected to the first power conversion circuit side. The third winding is connected to connection points provided between the secondary winding and the bridge circuit via the switching circuit.

Description

Power Conversion Device

[0001] The present invention relates to a power conversion device that converts DC power and AC power mutually.

[0002] Conventionally, power conversion devices mounted on vehicles having a storage battery that can be charged using an external power source and converting power supplied from the external power source to charge the storage battery or converting power discharged from the storage battery to supply power to a power outlet (power supply port) for general electrical appliances provided on the vehicle have been widely used. When supplying power to the outlet while the storage battery is being charged, such power conversion devices generally need to convert AC power supplied from the external power source to DC power corresponding to the charging voltage of the storage battery, and then convert the DC power to AC power corresponding to the voltage of the general electrical appliance, and output it to the outlet. As a result, power conversion between AC power and DC power is repeated, which poses a problem of reduced power supply efficiency due to conversion losses caused by these power conversions.

[0003] To solve the above problem, for example, a technology has been proposed in Patent Document 1. Patent Document 1 describes that in a vehicle equipped with a power storage device, a charging device, and an inverter, when an external power source is connected to the charging device to charge the power storage device while outputting power to an outlet, if the input voltage from the external power source is equal to the output voltage of the outlet, a relay arranged between the external power source and the outlet is turned on so that power is supplied from the external power source to the outlet without passing through the charging device and the inverter, thereby suppressing loss due to power conversion in the charging device and the inverter.

[0004] Japanese Patent Application Publication No. 2014-187774

[0005] The technology of Patent Document 1 can suppress losses due to power conversion and increase power supply efficiency by supplying power to an outlet without going through a charging device or inverter when the input voltage and output voltage are equal. However, when the input voltage and output voltage are different, power conversion by a charging device or inverter is still required, so it is not possible to prevent a decrease in power supply efficiency.

[0006] The present invention has been made in consideration of the above-mentioned problems, and a main object of the present invention is to suppress a decrease in power supply efficiency when the input voltage and output voltage are different in a power conversion device that supplies power to a power supply port while a storage battery is being charged.

[0007] A power conversion device according to the present invention includes a first power conversion circuit that converts output power from a storage battery mounted on a vehicle into power to be output to a power supply port provided on the vehicle; a second power conversion circuit that converts input power from a charging port provided on the vehicle into power to be supplied to the storage battery; and a switching circuit that can be switched between a conductive state and a cut-off state, wherein the first power conversion circuit includes a first transformer having a primary winding connected to the storage battery side and a secondary winding connected to the power supply port side, and a bridge circuit connected between the secondary winding and the power supply port, and the second power conversion circuit includes a second transformer having a first winding connected to the charging port side, a second winding connected to the storage battery side, and a third winding connected to the first power conversion circuit side, and the third winding is connected to a connection point provided between the secondary winding and the bridge circuit via the switching circuit.

[0008] According to the present invention, in a power conversion device that supplies power to a power supply port while a storage battery is being charged, it is possible to suppress a decrease in power supply efficiency when the input voltage and the output voltage differ.

[0009] 1 is a diagram showing a schematic configuration of a power conversion device according to an embodiment of the present invention; and FIG. 2 is a control flow diagram of the power conversion device according to an embodiment of the present invention.

[0010] Fig. 1 is a diagram showing the schematic configuration of a power conversion device according to one embodiment of the present invention. The power conversion device 1 shown in Fig. 1 performs power conversion when charging a storage battery 2 mounted on a vehicle from an external source, and when supplying power to general electrical equipment using power stored in the storage battery 2, and is connected to the storage battery 2, a power supply port 3, and a charging port 4.

[0011] The storage battery 2 is a rechargeable power storage device mounted on the vehicle and is configured using a rechargeable secondary battery such as a lithium-ion battery. For example, DC power for driving a drive motor (not shown) is supplied from the storage battery 2 to an inverter (not shown), and the inverter converts this DC power into AC power and outputs it to the drive motor, thereby operating the drive motor to drive the vehicle.

[0012] The power supply port 3 is an outlet for general electrical devices provided in the vehicle. For example, DC power supplied from the storage battery 2 can be converted by the power conversion device 1 into single-phase AC power or three-phase AC power of a predetermined voltage and output from the power supply port 3 to supply power to general electrical devices connected to the power supply port 3. In addition, DC power supplied from the power supply port 3 may be used to charge a storage battery installed in another vehicle, etc.

[0013] The charging port 4 is connected to an external power source via a charging cable (not shown). For example, a commercial power source supplied from an ordinary home can be used as the external power source. By connecting the charging port 4 to the external power source and converting AC power supplied from the external power source into DC power of a predetermined voltage using the power conversion device 1, the storage battery 2 can be charged.

[0014] The power conversion device 1 includes a first power conversion circuit 11 , a second power conversion circuit 12 , a switching circuit 13 , a power detection unit 14 , and a voltage conversion control unit 15 .

[0015] The first power conversion circuit 11 includes a first bridge circuit 111 , a first transformer 112 , a second bridge circuit 113 , and a third bridge circuit 114 .

[0016] The first bridge circuit 111 is configured by combining a plurality of (e.g., four) switch elements, and converts DC power output from the storage battery 2 into AC power by operating these switch elements at predetermined timings. The first transformer 112 has a primary winding C11 connected to the storage battery 2 side (first bridge circuit 111 side) and a secondary winding C12 connected to the power supply port 3 side (second bridge circuit 113 side), and changes the voltage of the AC power output from the first bridge circuit 111 at a voltage ratio corresponding to the turns ratio of the primary winding C11 and the secondary winding C12 and outputs the changed voltage to the second bridge circuit 113. The second bridge circuit 113 is an active ridge rectifier configured by combining a plurality of (e.g., four) switch elements, and converts AC power output from the first transformer 112 into DC power by operating these switch elements at predetermined timings. The third bridge circuit 114 is configured by combining multiple (e.g., four) switch elements, and by operating these switch elements at predetermined timings, the DC power output from the second bridge circuit 113 is converted into AC power suitable for output from the power supply port 3.

[0017] In the first power conversion circuit 11, each of the first bridge circuit 111, the first transformer 112, the second bridge circuit 113, and the third bridge circuit 114 performs the operations described above, thereby converting the output power from the storage battery 2 into power to be output to the power supply port 3.

[0018] The second power conversion circuit 12 includes a power factor correction circuit 121 , a fourth bridge circuit 122 , a second transformer 123 , and a fifth bridge circuit 124 .

[0019] The power factor correction circuit 121 performs a predetermined power factor correction process on the AC power supplied from the external power supply via the charging port 4 and then converts the AC power into DC power. The fourth bridge circuit 122 is configured by combining a plurality of (for example, four) switch elements, and converts the DC power output from the power factor correction circuit 121 into AC power by operating these switch elements at predetermined timings. The second transformer 123 has a first winding C21 connected to the charging port 4 side (fourth bridge circuit 122 side), a second winding C22 connected to the storage battery 2 side (fifth bridge circuit 124 side), and a third winding C23 connected to the first power conversion circuit 11 side, and changes the voltage of the AC power output from the fourth bridge circuit 122 at a voltage ratio corresponding to the turns ratio between the first winding C21 and the second winding C22 and outputs the changed voltage to the fourth bridge circuit 122, and also changes the voltage of the AC power output from the fourth bridge circuit 122 at a voltage ratio corresponding to the turns ratio between the first winding C21 and the third winding C23 and outputs the changed voltage to the first power conversion circuit 11. The fifth bridge circuit 124 is configured by combining a plurality of (e.g., four) switch elements, and converts the AC power output from the second transformer 123 into DC power by operating these switch elements at predetermined timings.

[0020] In the second power conversion circuit 12, each of the power factor correction circuit 121, the fourth bridge circuit 122, the second transformer 123, and the fifth bridge circuit 124 performs the operations described above, thereby converting the input power from the charging port 4 into power to be supplied to the storage battery 2.

[0021] The switching circuit 13 is a circuit that can be switched between a conductive state and a cut-off state, and is connected between the first power conversion circuit 11 and the second power conversion circuit 12. One end of the switching circuit 13 is connected to connection points CP1 and CP2 provided between the first transformer 112 and the second bridge circuit 113 in the first power conversion circuit 11. The other end of the switching circuit 13 is connected to the third winding C23 of the second transformer 123 in the second power conversion circuit 12. As a result, the third winding C23 of the second transformer 123 is connected to the connection points CP1 and CP2 via the switching circuit 13.

[0022] The power conversion device 1 can detect the input to the charging port 4 and the output from the power supply port 3. When input power from the external power source is detected at the charging port 4 and output power from the power supply port 3 is also detected, the power conversion device 1 switches the switching circuit 13 to a conductive state. This allows AC power output from the fourth bridge circuit 122 in the second power conversion circuit 12 to be input directly to the second bridge circuit 113 of the first power conversion circuit 11 without passing through the storage battery 2 when the storage battery 2 is being charged using power supplied from the external power source. On the other hand, in other cases, the power conversion device 1 switches the switching circuit 13 to a non-conductive state.

[0023] In the first power conversion circuit 11, a switch S1 is provided between the connection points CP1, CP2 and the secondary winding C12 of the first transformer 112. The power conversion device 1 opens the switch S1 when switching the switching circuit 13 to a conductive state. As a result, when AC power is directly input from the second power conversion circuit 12 to the first power conversion circuit 11 without passing through the storage battery 2, the switch S1 blocks the AC power from being input to the storage battery 2 side via the first transformer 112.

[0024] The power detection unit 14 detects the power output from the third winding C23 of the second transformer 123 to the first power conversion circuit 11 via the switching circuit 13. The voltage conversion control unit 15 controls the operation of the second bridge circuit 113 based on the frequency and voltage of the power detected by the power detection unit 14. This enables the second bridge circuit 113 and the third bridge circuit 114 to convert the AC power input from the second power conversion circuit 12 without passing through the storage battery 2 into AC power suitable for output from the power feeding port 3.

[0025] 2 is a control flow diagram of a power conversion device according to one embodiment of the present invention. The power conversion device 1 performs power conversion processing according to the connection state of the power supply port 3 and the charging port 4 by executing processing according to the control flow diagram of FIG. 2 at a predetermined processing cycle.

[0026] In step S10, it is determined whether or not there is an output to the power supply port 3. If there is an output to the power supply port 3, the process proceeds to the next step S20.

[0027] In step S20, it is determined whether or not there is power being supplied from the charging port 4. If there is power being supplied from the charging port 4, the process proceeds to step S30, and if there is no power being supplied, the process proceeds to step S50.

[0028] In step S30, the switching circuit 13 is switched to a conductive state, and the switch S1 is opened to switch the input to the second bridge circuit 113 to the second transformer 123. In step S40, the power detection unit 14 detects the power output from the third winding C23 of the second transformer 123, and the voltage conversion control unit 15 controls the second bridge circuit 113 in accordance with the frequency and voltage of that power. After the processing of step S40 has been executed, the control flow diagram in FIG. 2 ends.

[0029] In step S50, the switching circuit 13 is switched to the interrupted state, and the switch S1 is closed to switch the input to the second bridge circuit 113 to the first transformer 112. In step S60, the first bridge circuit 111, the first transformer 112, the second bridge circuit 113, and the third bridge circuit 114 in the first power conversion circuit 11 are operated, and power is output from the storage battery 2 to the power supply port 3 via these circuits. After the processing of step S60 has been executed, the control flow diagram in FIG. 2 ends.

[0030] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0031] (1) The power conversion device 1 includes a first power conversion circuit 11 that converts output power from a storage battery 2 mounted on a vehicle into power to be output to a power supply port 3 provided in the vehicle, a second power conversion circuit 12 that converts input power from a charging port 4 provided in the vehicle into power to be supplied to the storage battery 2, and a switching circuit 13 that can be switched between a conductive state and a cut-off state. The first power conversion circuit 11 includes a first transformer 112 having a primary winding C11 connected to the storage battery 2 side and a secondary winding C12 connected to the power supply port 3 side, and a second bridge circuit 113 connected between the secondary winding C12 and the power supply port 3. The second power conversion circuit 12 includes a second transformer 123 having a first winding C21 connected to the charging port 4 side, a second winding C22 connected to the storage battery 2 side, and a third winding C23 connected to the first power conversion circuit 11 side. The third winding C23 is connected via the switching circuit 13 to connection points CP1 and CP2 provided between the secondary winding C12 and the second bridge circuit 113. As a result, in the power conversion device 1 that supplies power to the power supply port 3 while the storage battery 2 is being charged, the AC power output from the fourth bridge circuit 122 of the second power conversion circuit 12 can be input directly to the second bridge circuit 113 of the first power conversion circuit 11 without passing through the storage battery 2. Therefore, even when the input voltage of the charging port 4 and the output voltage of the power supply port 3 differ, a decrease in power supply efficiency can be suppressed. Furthermore, because power can be supplied between the charging port 4 and the power supply port 3 without passing through the storage battery 2 while insulating them with the second transformer 123, it is possible to achieve both safety and power supply efficiency.

[0032] (2) In the power conversion device 1, when power is supplied from the power supply port 3 using the power output from the second power conversion circuit 12, the switching circuit 13 is switched to the conductive state (step S30). As a result, while the storage battery 2 is being charged, the AC power output from the fourth bridge circuit 122 of the second power conversion circuit 12 can be directly input to the second bridge circuit 113 of the first power conversion circuit 11 via the switching circuit 13 and used to supply power to the power supply port 3.

[0033] (3) The power conversion device 1 includes a switch S1 provided between the connection points CP1, CP2 and the secondary winding C12. When the switching circuit 13 is switched to the conductive state, the switch S1 is opened. This configuration prevents AC power input from the second power conversion circuit 12 to the first power conversion circuit 11 without passing through the storage battery 2 from being input to the storage battery 2 via the first transformer 112.

[0034] (4) The power conversion device 1 includes a power detection unit 14 that detects the power output from the third winding C23, and a voltage conversion control unit 15 that controls the operation of the second bridge circuit 113 based on the frequency and voltage of the power detected by the power detection unit 14. As a result, AC power input from the second power conversion circuit 12 to the first power conversion circuit 11 without passing through the storage battery 2 can be converted into AC power suitable for output from the power supply port 3.

[0035] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of an embodiment with other configurations. Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be implemented in hardware, in part or in whole, by, for example, designing them as integrated circuits. Furthermore, the above-described configurations, functions, etc. may be implemented in software, by a processor interpreting and executing a program that realizes each function. Information such as programs, tables, and files that realize each function may be stored in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

[0036] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0037] 1: power conversion device, 2: storage battery, 3: power supply port, 4: charging port, 11: first power conversion circuit, 12: second power conversion circuit, 13: switching circuit, 14: power detection unit, 15: voltage conversion control unit, 111: first bridge circuit, 112: first transformer, 113: second bridge circuit, 114: third bridge circuit, 121: power factor correction circuit, 122: fourth bridge circuit, 123: second transformer, 124: fifth bridge circuit

Claims

1. A power conversion device comprising: a first power conversion circuit that converts output power from a storage battery mounted on a vehicle into power to be output to a power supply port provided on the vehicle; a second power conversion circuit that converts input power from a charging port provided on the vehicle into power to be supplied to the storage battery; and a switching circuit that can be switched between a conductive state and a cut-off state, wherein the first power conversion circuit includes a first transformer having a primary winding connected to the storage battery side and a secondary winding connected to the power supply port side, and a bridge circuit connected between the secondary winding and the power supply port, and the second power conversion circuit includes a second transformer having a first winding connected to the charging port side, a second winding connected to the storage battery side, and a third winding connected to the first power conversion circuit side, and the third winding is connected to a connection point provided between the secondary winding and the bridge circuit via the switching circuit.

2. A power conversion device according to claim 1, wherein when power is supplied from the power supply port using power output from the second power conversion circuit, the switching circuit is switched to the conductive state.

3. A power conversion device according to claim 2, further comprising a switch provided between said connection point and said secondary winding, said switch being opened when said switching circuit is switched to said conductive state.

4. A power conversion device according to claim 1, comprising: a power detection unit that detects the power output from the third winding; and a voltage conversion control unit that controls the operation of the bridge circuit based on the frequency and voltage of the power detected by the power detection unit.

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