UENO, Satoru (1048, Oaza-Kadoma, Kadoma-sh, Osaka 86, 57186, JP)
| CLAIMS 1. A power feeding system for electric vehicle comprising: a DC distribution board comprising a distribution circuit, said distribution circuit being configured to distribute DC power from at least one DC power supply to a plurality of outputs." a bidirectional power feeding device configured to perform a charging operation for feeding a battery of an electric vehicle with DC power from the DC distribution board, and a feeding operation for supplying the DC distribution board with DC power from the battery of the electric vehicle; and a control device configured to generate a switching signal for changing the operation of the bidirectional power feeding device to either the charging operation or the feeding operation based on both power supplied from said at least one DC power supply and power required for the distribution circuit side, wherein the bidirectional power feeding device comprises: a control part configured to make the electric vehicle change its operation to either a charging operation of the battery or a feeding operation of the battery based on the switching signal generated by the control device; a vehicle side feeding part configured to supply the electric vehicle with DC power from the DC distribution board when the electric vehicle is charged; and a distribution board side feeding part configured to supply the DC distribution board with DC power from the electric vehicle when the electric vehicle discharges. 2. A power feeding system for electric vehicle as set forth in claim 1, wherein the DC distribution board is arranged in a building, wherein the electric vehicle is further equipped with a charge -discharge part for charging and discharging the battery, and a charge -discharge control part for controlling the operation of the charge-discharge part, wherein the bidirectional power feeding device is configured to supply the charge-discharge part of the electric vehicle with DC power supplied from the DC distribution board when the charging operation, and configured to supply the DC distribution board with DC power fed from the charge -discharge part of the electric vehicle when the feeding operation, wherein the control part of the bidirectional power feeding device is configured to, via the charge -discharge control part of the electric vehicle, make the charge -discharge control part of the electric vehicle change its operation to either a charging operation of the battery or a feeding operation of the battery based on the switching signal generated by the control device. 3. A power feeding system for electric vehicle as set forth in claim 2, wherein said at least one DC power supply comprises a storage battery, said storage battery being configured to be charged by DC power supplied from other DC power supply and configured to discharge when said other DC power supply stops feeding power, and wherein the storage battery is configured to be charged by DC power supplied from the distribution board side feeding part when the electric vehicle discharges. |
POWER FEED SYSTEM FOR ELECTRIC VEHICLE
TECHNICAL FIELD
[0001] The invention relates generally to a power feeding system for electric vehicle.
BACKGROUND ART
[0002] In recent years, electric vehicle such as Plug-in Hybrid Vehicle (PHV) or Battery Electric Vehicle (BEV) has been developed. As a way of charging the electric vehicle, it has been considered to feed the electric vehicle with the commercial AC (alternating current) power through an outlet of a house thereby charge the electric vehicle.
[0003] Besides, it has been examined to supply electrical apparatuses in a house with electric power by discharging a battery of the electric vehicle, if a power failure occurs while supplying the electric vehicle with the commercial AC power to charge the battery (For example, refer to Japanese Patent Application Laid-Open No. 2006-158084).
[0004] In the system disclosed in the above patent application, when charging the electric vehicle, commercial AC power is supplied to the electric vehicle and the AC is converted into DC (direct current) within the electric vehicle to charge the battery. Therefore, there is such a problem that conversion loss generates when converting AC into DC. Similarly, when discharging the electric vehicle, the DC power stored in the battery is converted into AC power and is supplied to the house side. Therefore, there is the problem that conversion loss generates when converting DC into AC. DISCLOSURE OF INVENTION
[0005] It is an object of the present invention to provide a power feeding system for electric vehicle which can skip the step of AC-DC conversion and/or DC-AC conversion when charging a battery of an electric vehicle and/or when discharging the battery to feed power to a house, and thereby efficiently uses electric power.
[0006] In order to achieve the above object, the present invention comprises- a DC distribution board comprising a distribution circuit, said distribution circuit being configured to distribute DC power from at least one DC power supply to a plurality of outputs, " a bidirectional power feeding device configured to perform a charging operation for feeding a battery of an electric vehicle with DC power from the DC distribution board, and a feeding operation for supplying the DC distribution board with DC power from the battery of the electric vehicle; and a control device configured to generate a switching signal for changing the operation of the bidirectional power feeding device to either the charging operation or the feeding operation based on both power supplied from said at least one DC power supply and power required for the distribution circuit side. The bidirectional power feeding device comprises " a control part configured to make the electric vehicle change its operation to either a charging operation of the battery or a feeding operation of the battery based on the switching signal generated by the control device; a vehicle side feeding part configured to supply the electric vehicle with DC power from the DC distribution board when the electric vehicle is charged; and a distribution board side feeding part configured to supply the DC distribution board with DC power from the electric vehicle when the electric vehicle discharges.
[0007] According to the present invention, when charging the battery of the electric vehicle, DC power is supplied from the DC distribution board to the electric vehicle through the bidirectional power feeding device. Therefore, there is no need to convert AC into DC in the electric vehicle side. For this reason, conversion loss does not generate for converting AC into DC. In addition, when discharging the battery of the electric vehicle thereby feeding power from the electric vehicle side, the bidirectional power feeding device directly supplies the DC distribution board with DC power stored in the battery of the electric vehicle. Therefore, there is no need to convert DC power supplied from the electric vehicle into AC power. For this reason, conversion loss does not generate for converting DC into AC. Therefore, electric power can be used efficiently.
[0008] In an embodiment, the DC distribution board is arranged in a building. The electric vehicle is further equipped with a charge -discharge part for charging and discharging the battery, and a charge -discharge control part for controlling the operation of the charge -discharge part. The bidirectional power feeding device is configured to supply the charge-discharge part of the electric vehicle with DC power supplied from the DC distribution board when the charging operation, and configured to supply the DC distribution board with DC power fed from the charge -discharge part of the electric vehicle when the feeding operation. The control part of the bidirectional power feeding device is configured to, via the charge -discharge control part of the electric vehicle, make the charge-discharge control part of the electric vehicle change its operation to either a charging operation of the battery or a feeding operation of the battery based on the switching signal generated by the control device.
[0009] In an embodiment, said at least one DC power supply comprises a storage battery, said storage battery being configured to be charged by DC power supplied from other DC power supply and configured to discharge when said other DC power supply stops feeding power. The storage battery is configured to be charged by DC power supplied from the distribution board side feeding part when the electric vehicle discharges.
[0010] According to this embodiment, DC power discharged from the battery of the electric vehicle can be stored in the storage battery.
BRIEF DESCRIPTION OF DRAWINGS
[0011] Preferred embodiments of the invention will now be described in further details. Other features and advantages of the present invention will become better understood with regard to the following detailed description and accompanying drawings where^
FIG. 1 is a diagram showing a system structure of an embodiment of the present invention. "
FIG. 2 is a diagram showing a system structure of another embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0012] An embodiment of the present invention is described below based on the attached figure.
[0013] The embodiment of the power feeding system for electric vehicle is not only configured to supply an electric vehicle, such as a Plug-in Hybrid Vehicle (PHV) or a Battery Electric Vehicle (BEV), with DC power to charge a battery of the electric vehicle, but also configured to supply house side with electric power stored in the battery of the electric vehicle by making the battery of the electric vehicle discharge when shortage of electricity occurs at the house side. In this embodiment, such a configuration that a power feed ng system for electric vehicle is applied to a detached house is explained. However, as a matter of course, a power feeding system for electric vehicle can be applied to such as a collective housing, a business office or another building.
[0014] Fig. 1 shows a schematic diagram of the power feeding system for electric vehicle. The power feeding system for electric vehicle includes a DC distribution board 1, a bidirectional power feeding device 2, a control device 3, and a setting/displaying device 4. The DC distribution board 1 is arranged at a house H, and is configured to distribute DC power supplied from DC power supply to branch circuits arranged in the house H. The bidirectional power feed ng device 2 is configured to perform a charging operation for feeding a battery of an electric vehicle with DC power from the DC distribution board, and a feeding operation for supplying the DC distribution board with DC power from the battery of the electric vehicle. For example, the bidirectional power feeding device 2 is configured to perform either a charging operation or a feeding operation. The bidirectional power feeding device 2 feeds a charge -discharge circuit 63 of an electric vehicle 60 with DC power supplied from the DC distribution board 1 in the charging operation. The bidirectional power feeding device 2 supplies the DC distribution board 1 with DC power fed from the charge -discharge circuit 63 of the electric vehicle 60 in the feeding operation.
[0015] The electric vehicle 60 includes a connector 61, a battery 62 such as a lithium-ion battery, the charge -discharge circuit 63, a communication circuit 64 and a charge -discharge control circuit 65. The connector 61 is configured to be detachably attached to a feed connector 26. Here, the feed connector 26 is provided at the end of a charging cable CA led out from the bidirectional power feeding device 2. The charge -discharge circuit 63 is configured to charge and discharge the battery 62. The communication circuit 64 is configured to communicate with the bidirectional power feeding device 2. The charge -discharge control circuit 65 is configured, based on a switching signal supplied from the bidirectional power feeding device 2 and received by the communication circuit 64, to change the operation of the charge-discharge circuit 63 to either a charging operation or a feeding operation.
[0016] The DC distribution board 1 is in conformity with 300 V class DC voltage. A cooperation control part 11 and a plurality of DC circuit breakers 12 are embedded in the DC distribution board 1. The cooperation control part 11 is configured to cooperate DC power supplied from a plurality of DC power supplies, and to supply to a load circuit. The plurality of DC circuit breakers 12 are connected between an output terminal of the cooperation control part 11 and the branch circuits of plural systems, respectively. Each of the DC circuit breakers 12 has an output for being connected with a branch circuit. In this embod ment, a distribution circuit 10 includes the plurality of DC circuit breakers 12. A DC-DC converter 13, a DC-DC converter 14, a DC-DC converter 15 and an AC-DC converter 16 are included in the DC distribution board 1. The DC-DC converter 13 is configured to convert DC voltage generated by a photovoltaic facility 50 into DC voltage of a predetermined voltage value. The DC-DC converter 14 is configured to convert DC voltage generated by a fuel cell 51 into DC voltage of the predetermined voltage value. The DC-DC converter 15 is configured to convert DC voltage supplied from a storage battery 52 into DC voltage of the predetermined voltage value. Here, the storage battery 52 is not only configured to be charged by other DC power supplies, but also configured to be discharged when said other DC power supplies stop feeding power. The AC-DC converter 16 is configured to convert AC power supplied from commercial AC power supply 100 into DC. Each outputs of the DC-DC converters 13~15 and the AC-DC converter 16 is connected with the cooperation control part 11 through DC power line LI. In the present embodiment, the photovoltaic facility 50, the fuel cell 51, the storage battery 52, the DC-DC converters 13, 14, 15 which are configured to convert output of the corresponding DC power supply into the predetermined voltage value, and the AC-DC converter 16 which is configured to convert AC input from the commercial AC power supply 100 into DC, are included as at least one DC power supply.
[0017] The bidirectional power feeding device 2 includes a DC-DC converter (vehicle side feeding part) 21, a DC-DC converter (distribution board side feeding part) 22, an interface part 24, a communication part 25 and a control part 23. The DC-DC converter 21 is configured to convert DC power supplied from the DC circuit breaker 12 through a DC power line L2 into DC power of voltage value corresponding to the electric vehicle 60, and to supply to the electric vehicle 60. The DC-DC converter 22 is configured to convert the voltage value of DC voltage supplied from the electric vehicle 60, and to output to the DC power line LI. The interface part 24 is configured to transmit signals to and from the control device 3. The communication part 25 is configured to communicate with the communication circuit 64 of the electric vehicle 60 through a communication line L4. The control part 23 is configured to control the operation of the DC-DC converters 21, 22 based on signals supplied from the control device 3 or the electric vehicle 60. In the present embodiment, the signal, which is transferred between the communication part 25 of the bidirectional power feeding device 2 and the communication circuit 64 of the electric vehicle 60, is transmitted through the dedicated communication line L4 incorporated in the charging cable CA. However, the signal may be superimposed on and transmitted through a power line L3 by way of power line communication. The signal may be transmitted by way of short distance wireless communication.
[0018] The control device 3 has a function that can control amount of DC power fed from the DC distribution board 1. The control device 3 is configured to control each electric power fed from the DC-DC converter 13-15 and the AC-DC converter 16 individually, thereby determines the feed ratio between the plurality of DC power supplies. The control device 3 also has a function that can supply the bidirectional power feeding device 2 with information about power feeding capacities of the plurality of the DC power supplies. The bidirectional power feeding device 2 is configured to control, based on the information about the power feeding capacities supplied from the control device 3, the DC-DC converter 21, thereby control DC power fed to the electric vehicle 60 so that the DC power fed to the electric vehicle 60 does not exceed the power feeding capacities of the DC power supplies.
[0019] The setting/displaying device 4 includes a liquid-crystal display monitor with touch panel. The setting/displaying device 4 is configured to display the feeding condition of the DC power supplies on the screen. In addition, by the touch operations of operation buttons displayed on the screen, a variety of setting conditions can be set to the control device 3 through the setting/displaying device 4.
[OO2O] Now, charge/discharge operation of the electric vehicle 60 by using the present power feeding system is explained.
[0021] The control device 3 compares the power from the DC power supplies (a supply power) with the power required for the branch circuit side (a required power). If the supply power from the DC power supplies is higher than the required power, the control device 3 supplies the bidirectional power feeding device 2 with a switching signal for switching the operation of the bidirectional power feeding device 2 to the charging operation, thereby the control device 3 makes the bidirectional power feeding device 2 feed power to the electric vehicle 60. Thus, the control device 3 makes the bidirectional power feeding_device 2 charge the battery 62 of the electric vehicle 60 preferentially. After completion of the charge of the battery 62, the control device 3 performs to charge the storage battery 52 by use of other DC power supplies. The control device 3 may be configured, after completion of the charge of the storage battery 52, to convert DC power supplied from the DC power supplies into AC power through a DC-AC converter (not shown in figure) and to supply to AC devices. On the other hand, if the supply power from the DC power supplies is lower than the required power, the control device 3 first makes the storage battery 52 discharge. After the discharge of the storage battery 52, the control device 3 supplies the bidirectional power feeding device 2 with a switching signal for switching the operation of the bidirectional power feeding device 2 to the feeding operation, thereby the control device 3 makes the bidirectional power feeding device 2 feed the DC distribution board 1 side with DC power discharged by the battery 62 of the electric vehicle 60. That is, the present embodiment is configured to switch the operation of the bidirectional power feeding device 2 to the feeding operation if the supply power from the DC power supply is lower than the required power.
[0022] In this embodiment, the required power is, for example, a total amount of electric power required for the operation of loads connected to the distribution circuit 10. The required power may be set to the control device 3 through an external setting device. For example, the required power is set to the control device 3 via a home server which is configured to manage the operation of the loads. In this case, the home server is connected with a plurality of loads each of which is connected to the outputs of the distribution circuit 10. Each loads is configured to provide the home server with information about electric power necessary for its own operation. The home server manages the information provided from the loads, and calculates the total amount of electric power required for the loads. The home server sends the total amount, as the required power, to the control device 3.
[0023] In the case of charging the electric vehicle 60, when the feed connector 26 of the charging cable CA led out from the bidirectional power feeding device 2 is connected to the connector 61 of the electric vehicle 60, the control part 23 of the bidirectional power feeding device 2 makes the communication part 25 supply the electric vehicle 60 side with a charge information sending request. Here, the charge information sending request is a request for sending charge information about charging voltage and charging current. When the communication circuit 64 of the electric vehicle 60 receives the charge information sending request sent from the bidirectional power feeding device 2, the charge-discharge control circuit 65 makes the communication circuit 64 supply the bidirectional power feeding device 2 with the charge information about charging voltage and charging current of own vehicle. After the charge information being received by the communication part 25 of the bidirectional power feeding device 2, the control part 23 of the bidirectional power feeding device 2 decides that whether power feeding from the DC distribution board 1 is possible or not based on both the charge information received by the communication part 25 and the power feeding capacities of the DC power supplies obtained from the control device 3 through the interface part 24. And then, the control part 23 controls output of the DC'DC converter 21, with a current value possible to supply and with the voltage value requested by the electric vehicle 60 side, thereby feeds power to the electric vehicle 60 side.
[0024] In the present embodiment, the photovoltaic facility 50, the fuel cell 51, the storage battery 52, and a DC power supply obtained by converting the AC output from the commercial AC power supply 100 into DC through the AC-DC converter 16, are used as DC power supplies for supplying the DC distribution board 1 with DC power. In the present embodiment, the control device 3 automatically performs a processing of selecting at least one DC power supply for feeding power to the electrical vehicle 60 from among the plurality of the DC power supplies. In this embodiment, power fed from the AC-DC converter 16 can be set to the control device 3 through the setting/displaying device 4. For example, upper limit of the power fed from the AC-DC converter 16 is set to the control device 3 through the setting/displaying device 4.
[0025] For example, in the case of charging the battery 62 of the electric vehicle 60 side, it is assumed that electric power fed from the AC-DC converter 16, which is configured to convert the AC input of the commercial AC power supply 100 into DC, is set at zero by use of the setting/displaying device 4, the sunlight exists (that is, power generation is performed by the photovoltaic facility 50), and there exists electric power stored in the storage battery 52. In addition, assuming that the electric vehicle 60 sends, in response to the charge information sending request, such a charge information that the charging voltage is DC 300 V and the charging current is 20 A to the bidirectional power feeding device 2. Then, this charge information is further sent from the bidirectional power feeding device 2 to the control device 3. Here, the control device 3 is configured to grasp the power feeding capacity of each DC power supplies. Assuming that the power generation of the photovoltaic facility 50 is 2000 VA, the power generation of the fuel cell 51 is 0 VA, the power feeding capacity of the storage battery 52 is 1000 VA, and no power is consumed by other electric devices in the house H. In this case, the control device 3 decides that possible feeding power to the electric vehicle 60 is 3000 VA. The control device 3 controls the DC-DC converter 13 and the DC-DC converter 15, and performs power feeding to the electric vehicle 60 in the condition that the charging voltage is 300 V and the charging current is 10 A, by using the photovoltaic facility 50 and the storage battery 52 as power supplies.
[0026] Next, assuming that the sunlight does not exist while the other conditions are same with the above case. In this case, the control device 3 decides that the possible feeding power to the electric vehicle 60 is 1000 VA, which corresponds to the power feeding capacity of the storage battery 52. Then, the control device 3 controls the DC-DC converter 15, and performs power feeding to the electric vehicle 60 in the condition that the charging voltage is 300 V and the charging current is 3.3 A, by using the storage battery 52 as a power supply.
[0027] Next, assuming that electric power fed from the AC-DC converter 16, which is configured to convert the AC input of the commercial AC power supply 100 into DC, is set at 1000 VA, the sunlight does not exist, and there exists electric power stored in the storage battery 52 and its power feeding capacity is 1000 VA. In this case, the control device 3 decides that the possible feeding power to the electric vehicle 60 is 2000 VA. Then, the control device 3 controls the DC-DC converter 15 and the AC-DC converter 16, and performs power feeding to the electric vehicle 60 in the condition that the charging voltage is 300 V and the charging current is 6.6 A, by using the AC-DC converter 16, which is configured to convert the AC input of the commercial AC power supply 100 into DC, and the storage battery 52 as power supplies.
[0028] Here, the control device 3 is configured to automatically select at least one optimum DC power supply based on a prehminarily-configured selection rule. However, what kind of DC power supply is preferentially used for feeding power can be set to the control device 3 by using the setting/displaying device 4.
[0029] DC power is supplied from the DC distribution board 1 to the electric vehicle 60 side as the above described way, and the battery 62 is charged through the charge-discharge circuit 63 of the electric vehicle 60. Here, if power feeding from DC power supply is stopped, the control device 3 sends the switching signal to the electric vehicle 60 through the bidirectional power feeding device 2. And then, the charge-discharge circuit 63 of the electric vehicle 60 makes the battery 62 discharge, thereby DC power is supplied from the battery 62 to the DC distribution board 1 side.
[0030] For example, assuming such a condition that during nighttime etc., the electric vehicle 60 is being charged, power conversion of the commercial AC power supply 100 is set at minimum by using the setting/displaying device 4, and the planed running distance for the next day of the electric vehicle 60 is set at 50km. Because the photovoltaic facility 50 does not generate electric power during nighttime, the present power feeding system is to both charge the electric vehicle 60 and feed power to the loads in the house H, by using the fuel cell 51 and the storage battery 52 as power supplies. If the power feeding capacity of combination of the fuel cell 51 and the storage battery 52 is lower than the power required for the loads in the house H, the control device 3 outputs the switching signal, which makes the operation of the bidirectional power feeding device 2 change from the charging operation for charging the battery 62 of the electric vehicle 60 to the discharging operation (the feeding operation) for discharging the battery 62, to the bidirectional power feeding device 2. The bidirectional power feeding device 2 sends this switching signal to the electric vehicle 60. Then, the charge -discharge control circuit 65 of the electric vehicle 60 makes the charge-discharge circuit 63 perform the discharging operation (the feeding operation) based on the switching signal received by the communication circuit 64, and thereby DC power stored in the battery 62 is discharged to the bidirectional power feeding device 2 through the power line L3. In the bidirectional power feeding device 2, in this time, in accordance with the switching signal input from the control device 3, the control part 23 not only makes the operation of the DC-DC converter 21 stop, but also makes the DC-DC converter 22 convert DC voltage supplied from the electric vehicle 60 (for example, 300 V) into a transmission voltage value in conformity with a power line of the house (for example, 350 V) and to output to the DC power line LI. Therefore, the present power feeding system can supply the loads in the house H with DC power by using the battery 62 of the electric vehicle 60 as a power supply.
[0031] By the way, when the planed running distance for the next day is set by using the setting/displaying device 4, the control device 3 sends the setting information about the planed running distance to the electric vehicle 60 through the bidirectional power feeding device 2. The charge-discharge control circuit 65 of the electric vehicle 60 decides a necessary battery level which is required for driving the planed running distance based on the setting information supplied from the bidirectional power feeding device 2. After starting the discharge of the battery 62 in accordance with the switching signal input from the bidirectional power feeding device 2, the charge -discharge control circuit 65 compares a remaining battery level of the battery 62 with the necessary battery level. If the remaining battery level of the battery 62 is lower than the necessary battery level, the charge-discharge control circuit 65 automatically controls the charge-discharge circuit 63 to stop the discharge of the battery 62. Therefore, the battery level necessary for driving the planed running distance can be ensured.
[0032] In addition, the charge-discharge control circuit 65 is configured, when the discharge of the battery 62 is stopped, to make the communication circuit 64 send a discharge stop signal for reporting the stop of discharge to the bidirectional power feeding device 2. When receiving the discharge stop signal, the bidirectional power feeding device 2 makes the operation of the DC-DC converter 22 stop as well as makes the interface part 24 send the discharge stop signal to the control device 3. When the control device 3 receiving the discharge stop signal, in order to compensate the shortfall in power caused by the stop of discharge of the electric vehicle 60, the control device 3 makes the AC-DC converter 16 work, and thereby the control device 3 makes the AC-DC converter 16 convert AC power supplied from the commercial AC power 100 into DC power, and to supply the storage battery 52 and the loads with the DC power.
[0033] In the present power feeding system, even if an excess current flows and/or an electrical leakage occurs when discharging the battery 62 of the electric vehicle 60 to supply the DC electricity distribution system of the house H with the discharged power, the loads in the house H are to be protected by an earth leakage breaker (not shown in figure) and/or the DC circuit breakers 12 arranged in the DC distribution board 1.
[0034] As explained above, in this power feeding system for electric vehicle, when charging the battery 62 of the electric vehicle 60, DC power is supplied from the DC distribution board 1 to the electric vehicle 60 through the bidirectional power feeding device 2. Therefore, there is no need to convert AC into DC in the electric vehicle 60 side. For this reason, conversion loss for converting AC into DC does not generate. In addition, when discharging the battery 62 of the electric vehicle 60 to feed power from the electric vehicle 60 side, the bidirectional power feeding device 2 supplies the DC distribution board 1 with DC power stored in the battery 62 of the electric vehicle 60. Therefore, there is no need to convert DC power supplied from the electric vehicle 60 into AC power. For this reason, conversion loss for converting DC into AC does not generate. Therefore, electric power can be used efficiently.
[0035] In the above power feeding system for electric vehicle, the storage battery 52 may be charged by DC power discharged by the battery 62 of the electric vehicle 60. In this configuration, DC power stored in the battery 62 of the electric vehicle 60 can be used effectively by the loads in the house H.
[0036] In the above power feeding system for electric vehicle, the bidirectional power feeding device 2 includes two DC-DC converters 21, 22. The DC-DC converter 21 is configured to perform voltage conversion of DC power supplied from the house side to supply to the electric vehicle 60 side when charging. The DC-DC converter 22 is configured to perform conversion of DC power supplied from the electric vehicle 60 to supply the house side with the DC power when discharging. However, as shown in Fig. 2, the bidirectional power feeding device 2 may include one DC-DC converter 27 which is compatible with both the charge from the house side and the discharge from the vehicle side. The DC-DC converter 27 is so configured that the operation of which is controlled by a control signal supplied from the control part 23. The DC-DC converter 27 is configured, when charging, to perform voltage conversion of the DC power supplied through a branch breaker (DC circuit breaker) 12 to supply to the electric vehicle 60 side. The DC-DC converter 27 is also configured, when discharging, to perform the conversion of the voltage value of the DC power supplied from the electric vehicle 60 to supply to the house side (the cooperation control part 11).
[0037] Although the present invention has been described with reference to certain preferred embodiments, numerous modifications and variations can be made by those skilled in the art without departing from the true spirit and scope of this invention, namely claims.