JP7802569B2 - power supply device - Google Patents

Description

The present invention relates to a power supply device that transfers power between a main battery installed in an electric vehicle and an external device.

Electric vehicles have recently become popular. Electric vehicles use a high-capacity lithium-ion battery as the main battery, and the driving motor is powered by the electricity stored in the main battery. In addition to the main battery, electric vehicles also generally have an auxiliary battery, such as a lead-acid battery, which serves as a power source for electrical components. The auxiliary battery is charged, for example, by the supply of electricity stored in the main battery while the electric vehicle is running.

Patent Document 1 proposes an electric vehicle charging device that charges the main battery from an external AC power source via a charger, and charges the auxiliary battery from the main battery via a DC-DC converter. This electric vehicle charging device is configured to stop operation of the DC-DC converter while the charger performs constant current charging at the beginning of charging, thereby reducing the capacity and size of the charger.

Japanese Unexamined Patent Publication No. 7-111711

In recent years, wireless charging systems that charge the main battery of an electric vehicle without using a charging cable or the like have been put into practical use. Electric vehicles that support wireless charging are equipped with a device that controls charging and communicates with the outside world, and this device operates on power supplied from the auxiliary battery. In electric vehicles in which the auxiliary battery is not charged while the main battery is being charged, as in the electric vehicle charging device described in Patent Document 1, power from the auxiliary battery is consumed while the main battery is being charged, which could result in the auxiliary battery running out of power.

Furthermore, the main battery installed in an electric vehicle may be used to extract stored power and operate an external device, such as a welding machine. In such cases, power from the auxiliary battery is consumed for control and communication between the electric vehicle and the external device, and there is a risk that the auxiliary battery may run out of power.

The present invention was made in consideration of these circumstances, and its purpose is to provide a power supply device that can be expected to prevent the auxiliary battery installed in an electric vehicle from running out of power.

In one embodiment, the power supply device exchanges power between a main battery mounted on an electric vehicle and an external device, and includes a first power path connecting the main battery and the external device, a second power path connecting an auxiliary battery mounted on the electric vehicle and a control power supply circuit, and a power supply circuit that receives power from the first power path and supplies power to the control power supply circuit.

In one embodiment, it is expected that the auxiliary battery installed in an electric vehicle can be prevented from running out of power.

1 is a block diagram for explaining a configuration of a power supply device according to a first embodiment. FIG. 10 is a block diagram for explaining the configuration of a power supply device according to a second embodiment. FIG. 10 is a block diagram for explaining the configuration of a power supply device according to a third embodiment. FIG. 10 is a block diagram for explaining the configuration of a power supply device according to a fourth embodiment.

Specific examples of power supply devices according to embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

First Embodiment
FIG. 1 is a block diagram illustrating the configuration of a power supply device according to a first embodiment. In this diagram, power supply paths are indicated by solid lines, and transmission paths for control signals and the like are indicated by dashed arrows. A vehicle 1 according to the first embodiment is an electric vehicle that travels by driving a motor 6 with power stored in a main battery 5 such as a lithium-ion battery. Note that the vehicle 1 may include a so-called hybrid electric vehicle that is equipped with both a motor 6 for travel and an engine that generates power by burning fuel.

The vehicle 1 according to the first embodiment is equipped with a function for charging the main battery 5 contactlessly without using a charging cable, i.e., a so-called wireless charging function. The vehicle 1 includes a power supply device 3 having a power receiving coil 2, an AC/DC converter 4, a main battery 5, a motor 6, a DC/DC converter 7, an auxiliary battery 8, and a control circuit 9. Of these, the power receiving coil 2 and the power supply device 3 are functional blocks for realizing the wireless charging function, and do not need to be installed in electric vehicles that do not have wireless charging function.

In contrast, the AC/DC converter 4, main battery 5, motor 6, DC/DC converter 7, auxiliary battery 8, and control circuit 9 are functional blocks that are installed in electric vehicles regardless of whether they have wireless charging functionality. In the case of electric vehicles that do not have wireless charging functionality, for example, a power supply device installed outside the vehicle is connected to the electric vehicle's AC/DC converter 4 via a charging cable, and AC power is supplied from the power supply device via the charging cable. The AC/DC converter 4 converts this AC power to DC power and supplies it to the main battery 5, thereby charging the main battery 5.

The power stored in the main battery 5 is supplied to the motor 6, which rotates the motor 6, driving the wheels of the vehicle 1 and propelling the vehicle 1. The main battery 5 is also connected to the DC/DC converter 7 via a switch SW, which is controlled by a control circuit 9 to turn on and off. When the switch SW is switched to the on state, the stored power is supplied to the DC/DC converter 7. The DC/DC converter 7 is a circuit that converts the voltage value of the direct current power supplied from the main battery 5. The output voltage of the main battery 5 is, for example, several hundred volts, and the DC/DC converter 7 converts this several hundred volts of power to, for example, 12 V and outputs it. The 12 V direct current power output by the DC/DC converter 7 is supplied to the auxiliary battery 8, which charges the auxiliary battery 8.

The auxiliary battery 8 stores power supplied from the main battery 5 via the DC/DC converter 7 and supplies 12V DC power to electrical equipment other than the motor 6 mounted on the vehicle 1, such as the control circuit 9. The control circuit 9 controls various electrical equipment mounted on the vehicle 1 and operates on power supplied from the auxiliary battery 8. In this embodiment, the control circuit 9 controls the conduction/cutoff of a switch SW provided between the main battery 5 and the DC/DC converter 7 depending on the on/off state of the vehicle 1's ignition switch or accessory switch. For example, the control circuit 9 cuts off the switch SW when the vehicle 1 is not running and wireless charging is performed (the ignition switch is off). As a result, while the vehicle 1 is performing wireless charging, power is not supplied from the main battery 5 to the auxiliary battery 8, and the auxiliary battery 8 is not charged.

The power supply device 3 according to the first embodiment can be added to an electric vehicle that charges the main battery 5 via a charging cable as described above, thereby adding wireless charging functionality to the electric vehicle. In this way, by consolidating the wireless charging functionality into the power supply device 3, it is expected that the manufacturing process and components will be standardized between electric vehicles with wireless charging functionality and electric vehicles without wireless charging functionality. It is also expected that it will be easier to add wireless charging functionality to electric vehicles without wireless charging functionality.

Wireless charging is a technology in which power is transmitted wirelessly from a power transmission coil (not shown) provided in a power supply device installed outside the vehicle 1 to a power receiving coil 2 provided in the power supply device 3 of the vehicle 1, for example, using electromagnetic induction or magnetic resonance. The power receiving coil 2 is located, for example, on the bottom of the vehicle 1, and the power transmission coil of the power supply device is located in a predetermined space, for example, a parking lot or a road. When the vehicle 1 is parked in this predetermined space, the power receiving coil 2 of the vehicle 1 and the power transmission coil of the external power supply device come into close proximity, and power is transmitted wirelessly from the power transmission coil to the power receiving coil 2.

The power supply device 3 according to this embodiment is configured to include a receiving coil 2, a control circuit 31, a rectifying and smoothing circuit 32, a DC/AC converter 33, a DC/DC converter 34, a capacitor 35, a diode D1, and a diode D2. The control circuit 31 controls the operation of each component within the power supply device 3 to perform wireless charging. In the illustrated example, the control circuit 31 controls the operation of the DC/AC converter 33, thereby outputting power received by the receiving coil 2 from a power supply device external to the vehicle 1 to the AC/DC converter 4 of the vehicle 1, thereby charging the main battery 5. The control circuit 31 may also wirelessly transmit and receive information regarding wireless charging to and from a power supply device installed external to the vehicle 1, for example.

The power supply input terminal of the control circuit 31 is connected to the output terminal of the DC/DC converter 34 via diode D1 and to the auxiliary battery 8 via diode D2. This allows the control circuit 31 to operate using power supplied from the DC/DC converter 34 via diode D1, or power supplied from the auxiliary battery 8 via diode D2.

The rectifying and smoothing circuit 32 combines a rectifying circuit that rectifies AC current to DC current and a smoothing circuit that smooths the pulsating current contained in the rectified DC current, and converts the AC power received by the receiving coil 2 into DC power for output. A DC/AC converter 33, a DC/DC converter 34, and a capacitor 35 are connected to the output terminals of the rectifying and smoothing circuit 32, respectively.

The DC/AC converter 33 is a circuit that converts DC power into AC power and outputs it. The DC/AC converter 33 switches the output on/off and controls the voltage value of the output power based on control signals provided by the control circuit 31. The power supply device 3 according to this embodiment is equipped with the DC/AC converter 33 because the main battery 5 of the vehicle 1 is charged using DC power output by the AC/DC converter 4, and the power supply device 3 outputs AC power suitable for input to the AC/DC converter 4. Therefore, in the block diagram shown in FIG. 1, it is also possible to eliminate the AC/DC converter 4 and DC/AC converter 33 and configure the power output by the rectifying and smoothing circuit 32 to be directly supplied to the main battery 5.

The DC/DC converter 34 is a circuit that converts the voltage value of the power output by the rectifying and smoothing circuit 32 into a predetermined voltage value and outputs it. In this embodiment, the DC/DC converter 34 outputs power at a voltage value (e.g., 15 V) higher than the output voltage value (e.g., 12 V) of the auxiliary battery 8. The output terminal of the DC/DC converter 34 is connected to the (power supply) input terminal of the control circuit 31 via diode D1, and the control circuit 31 can operate using the power supplied from the DC/DC converter 34.

Capacitor 35 is a circuit element that temporarily stores the power (charge) output by rectifying and smoothing circuit 32. When wireless charging begins, the AC power received by power receiving coil 2 is converted to DC power by rectifying and smoothing circuit 32 and output, and the power output by rectifying and smoothing circuit 32 is stored in capacitor 35. By storing power in capacitor 35, even if wireless charging is temporarily interrupted, for example, the DC/AC converter 33 and DC/DC converter 34 can continue to operate using the power stored in capacitor 35.

Diodes D1 and D2 are circuit elements that allow current to flow from anode to cathode but prevent current from flowing from cathode to anode. The anode of diode D1 is connected to the output terminal of DC/DC converter 34, and the cathode is connected to the power input terminal of control circuit 31. Power is supplied from DC/DC converter 34 to control circuit 31 via diode D1, but current does not flow from control circuit 31 to DC/DC converter 34. The anode of diode D2 is connected to auxiliary battery 8, and the cathode is connected to the power input terminal of control circuit 31. Power is supplied from auxiliary battery 8 to control circuit 31 via diode D2, but current does not flow from control circuit 31 to auxiliary battery 8. Diodes D1 and D2 may also be common-cathode center-tap diodes incorporating two diodes.

Diodes D1 and D2 included in the power supply device 3 in this embodiment form a selection circuit for selecting the power to be supplied to the control circuit 31. This selection circuit selects between power from the DC/DC converter 34 and power from the auxiliary battery 8 and supplies the selected power to the control circuit 31 depending on whether the DC/DC converter 34 is operating, i.e., whether wireless charging is occurring.

That is, when the DC/DC converter 34 is not operating, power output from the auxiliary battery 8, for example, at a voltage of 12 V, is supplied to the control circuit 31 via diode D2. When the DC/DC converter 34 is operating, power output from the DC/DC converter 34, for example, at a voltage of 15 V, is supplied to the control circuit 31 via diode D1. As a result, diode D2 enters a cut-off state in which no current flows because the anode voltage is 12 V and the cathode voltage is 15 V, and the power supply from the auxiliary battery 8 to the control circuit 31 is stopped. Note that in this embodiment, the output voltage of the DC/DC converter 34 is set to be higher than the output voltage of the auxiliary battery 8.

In this embodiment, when the vehicle 1 is running, power is supplied from the main battery 5 to the motor 6. At this time, the control circuit 9 places the switch SW in a conducting state, and power from the main battery 5 is supplied to the auxiliary battery 8 via the DC/DC converter 7, charging the auxiliary battery 8. When the vehicle 1 is parked in a parking lot or the like that is equipped with a power supply device for charging the main battery 5, and the ignition switch is switched to the off state, for example, the control circuit 9 switches the switch SW to the off state, thereby cutting off the power supply from the main battery 5 to the auxiliary battery 8.

At this time, the control circuit 31 of the power supply device 3 communicates wirelessly with, for example, a power feeding device installed outside the vehicle 1, and performs the specified procedures necessary to implement wireless charging. At this time, the control circuit 31 operates using power supplied from the auxiliary battery 8 via diode D2. After the specified procedures necessary for wireless charging are completed, wireless power transmission begins from the power transmission coil of the external power feeding device to the power receiving coil 2 of the vehicle 1, and the control circuit 31 starts operating the DC/AC converter 33. The power received by the power receiving coil 2 is supplied to the main battery 5 via the rectifying and smoothing circuit 32, DC/AC converter 33, and AC/DC converter 4, and the main battery 5 is charged.

When the receiving coil 2 receives power, the power output by the rectifying and smoothing circuit 32 is supplied to the DC/DC converter 34, which then begins operating. The DC/DC converter 34 outputs power at a voltage (e.g., 15 V) higher than the output voltage (e.g., 12 V) of the auxiliary battery 8, and this power is supplied to the control circuit 31 via diode D1. As power is supplied from the DC/DC converter 34 to the control circuit 31, the cathode of diode D2 becomes equal to or close to the output voltage (e.g., 15 V) of the DC/DC converter 34. The voltage at the anode of diode D2 is the output voltage (e.g., 12 V) of the auxiliary battery 8, and because the voltage at the cathode of diode D2 is higher than the voltage at the anode, diode D2 is cut off, and the power supply from the auxiliary battery 8 to the control circuit 31 is stopped.

The power supply device 3 according to the first embodiment, as configured above, is a device that transfers power between a main battery 5 mounted on a vehicle 1, such as an electric vehicle, and an external power supply device. The power supply device 3 includes a first power path connecting the main battery 5 and the external power supply device (i.e., a power path (e.g., wiring or cable) between the power receiving coil 2 and the rectifying and smoothing circuit 32, a power path between the rectifying and smoothing circuit 32 and the DC/AC converter 33, and a power path between the DC/AC converter 33 and the AC/DC converter 4). The power supply device 3 also includes a second power path connecting the auxiliary battery 8 mounted on the vehicle 1 and the control circuit 31 (i.e., a power path between the auxiliary battery 8 and the anode of diode D2, and a power path between the cathode of diode D2 and the control circuit 31). The power supply device 3 also includes a DC/DC converter 34 that receives power from the first power path and supplies it to the control circuit 31.

With these configurations, the power supply device 3 according to embodiment 1 can supply power from the auxiliary battery 8 of the vehicle 1 to the control circuit 31 to operate the control circuit 31 when wireless charging is not being performed. Furthermore, when wireless charging is being performed, the power supply device 3 can supply power from the DC/DC converter 34 to the control circuit 31 to operate the control circuit 31, which is expected to prevent the auxiliary battery 8 from running out of power.

The power supply device 3 according to embodiment 1 also includes a power supply selection circuit that selects power supplied from either the DC/DC converter 34 or the auxiliary battery 8, whichever has the higher output voltage, and supplies the power to the control circuit 31. The power supply selection circuit has two diodes D1 and D2, with the anode of diode D1 connected to the output terminal of the DC/DC converter 34, the anode of diode D2 connected to the second power path, and the cathodes of diodes D1 and D2 connected to each other and to the control circuit 31. By setting the output voltage of the DC/DC converter 34 higher than the output voltage of the auxiliary battery 8, it is possible to expect that when the DC/DC converter 34 is operating, power will be supplied from the DC/DC converter 34 to the control circuit 31 and power supply from the auxiliary battery 8 to the control circuit 31 will be stopped.

In the first embodiment, the power supply device 3 is configured to supply power of a predetermined voltage value output by the DC/DC converter 34 based on the power output by the rectifying and smoothing circuit 32 to the control circuit 31 via the diode D1, but this is not limited to this. For example, the power supply device 3 may be configured to include an AC/DC converter instead of the DC/DC converter 34, convert the AC power output by the DC/AC converter 33 into DC power using this AC/DC converter, and supply this power to the control circuit 31.

<Second Embodiment>
2 is a block diagram illustrating the configuration of a power supply device 3 according to a second embodiment. The power supply device 3 according to the second embodiment has a configuration in which a voltage detection unit 37 is added to the configuration of the power supply device 3 according to the first embodiment shown in FIG. 1. The voltage detection unit 37 is connected to an appropriate location on the power supply path between, for example, the auxiliary battery 8 and the diode D2. The voltage detection unit 37 detects the voltage value on this power supply path (the output voltage value of the auxiliary battery 8 and the voltage value at the anode of the diode D2) and outputs the detected voltage value to the control circuit 31.

The control circuit 31 of the power supply device 3 according to the second embodiment controls the operation of the DC/DC converter 34 in accordance with the voltage value detected by the voltage detection unit 37. The control circuit 31 determines whether the voltage value detected by the voltage detection unit 37 exceeds a predetermined voltage value, and if the detected voltage value exceeds the predetermined voltage value, i.e., if it is estimated that sufficient power has been stored in the auxiliary battery 8, the control circuit 31 stops the operation of the DC/DC converter 34. On the other hand, if the detected voltage value does not exceed the predetermined voltage value, i.e., if it is estimated that the power stored in the auxiliary battery 8 is decreasing, the control circuit 31 operates the DC/DC converter 34.

The power supply device 3 according to the second embodiment configured as described above detects the output voltage value of the auxiliary battery 8 using the voltage detection unit 37, and stops power supply from the DC/DC converter 34 if the detected voltage value exceeds a predetermined voltage value. As a result, when it is estimated that sufficient power has been stored in the auxiliary battery 8, the power supply device 3 can allocate the power used to operate the DC/DC converter 34 to charging the main battery 5, which is expected to enable efficient charging of the main battery 5.

Note that the power supply device 3 according to embodiment 2 is configured to stop the operation of the DC/DC converter 34 in accordance with the voltage value detected by the voltage detection unit 37, but this is not limited to this. For example, the power supply device 3 may perform control to change the output voltage value of the DC/DC converter 34 in accordance with the voltage value detected by the voltage detection unit 37.

Furthermore, the other configurations of the power supply device 3 according to embodiment 2 are the same as those of the power supply device 3 according to embodiment 1, so similar parts are given the same reference numerals and detailed descriptions are omitted.

<Third Embodiment>
3 is a block diagram for explaining the configuration of a power supply device 3 according to a third embodiment. The power supply device 3 according to the third embodiment corresponds to the configuration of the power supply device 3 according to the first embodiment shown in FIG. 1 , in which the diodes D1 and D2 are removed and the DC/DC converter 34 is replaced with a charging circuit 36. More specifically, in the power supply device 3 according to the third embodiment, the power input terminal of the control circuit 31 and the output terminal of the auxiliary battery 8 are directly connected without an intervening diode or the like. The control circuit 31 operates on power supplied from the auxiliary battery 8.

The charging circuit 36 operates based on the power output by the rectifying and smoothing circuit 32, and outputs power at a predetermined voltage value at which the control circuit 31 operates. Furthermore, the charging circuit 36 is a circuit that can perform constant current output operation at a predetermined current value required to charge the auxiliary battery 8, even when the auxiliary battery 8 is connected to its output and the output voltage value of the auxiliary battery 8 is lower than the predetermined voltage value.

When wireless charging begins and the rectifying and smoothing circuit 32 outputs DC power, the charging circuit 36 begins outputting a constant current. The current output by the charging circuit 36 is supplied to the control circuit 31 and the auxiliary battery 8, which operates the control circuit 31 and charges the auxiliary battery 8.

In the power supply device 3 according to embodiment 3 configured as described above, when wireless charging is being performed, the charging circuit 36 supplies a constant current to the control circuit 31 and the auxiliary battery 8, thereby operating the control circuit 31 and charging the auxiliary battery 8. Therefore, the power supply device 3 according to embodiment 3 is expected to prevent the auxiliary battery 8 from running out of power.

Note that the other configurations of the power supply device 3 according to embodiment 3 are the same as those of the power supply device 3 according to embodiments 1 and 2, so similar parts are given the same reference numerals and detailed descriptions are omitted.

<Fourth Embodiment>
4 is a block diagram for explaining the configuration of a power supply device 3 according to embodiment 4. The power supply devices 3 according to the above-described first to third embodiments are configured to supply power from a power feeding device provided outside the vehicle 1 to the main battery 5 inside the vehicle 1. In contrast, the power supply device 3 according to embodiment 4 is configured to supply power stored in the main battery 5 inside the vehicle 1 to various devices outside the vehicle 1.

In the fourth embodiment, a welding machine 51 having the functions of the power supply device 3 is used as an example of a device external to the vehicle 1, but the external device is not limited to the welding machine 51 and may be any device. The vehicle 1 according to the fourth embodiment has the function of supplying power stored in the main battery 5 to an external device, for example, by connecting a power supply cable to a plug located in an appropriate location on the vehicle body. The plug to which the power supply cable for external power supply is connected may be the same as or different from the plug to which the charging cable is connected when charging the main battery 5 via a wired connection.

The welding machine 51 according to the fourth embodiment is provided outside the vehicle 1 and operates using power supplied from the vehicle 1. The welding machine 51 according to the fourth embodiment is equipped with a control circuit 31, a DC/DC converter 34, and diodes D1 and D2 similar to those of the power supply device 3 according to the first embodiment, as well as a rectifying and smoothing circuit 52, an inverter 53, a rectifying circuit 54, etc.

When the welding machine 51 is connected to the vehicle 1, the power output from the vehicle 1's main battery 5 passes through the welding machine's rectifying and smoothing circuit 52, inverter 53, and rectifying circuit 54, and is supplied to various components (not shown) within the welding machine 51. The rectifying and smoothing circuit 52 combines a rectifying circuit that rectifies current and a smoothing circuit that smooths it, and outputs the power from the vehicle 1's main battery 5 as DC power. The inverter 53 and DC/DC converter 34 are connected to the output terminals of the rectifying and smoothing circuit 52, respectively.

The inverter 53 is a circuit that converts DC to AC. The inverter 53 converts the DC power output by the rectifying and smoothing circuit 52 into AC power of a predetermined voltage value and a predetermined frequency under the control of the control circuit 31 and outputs it. A rectifying circuit 54 is connected to the output terminal of the inverter 53, and the rectifying circuit 54 converts the AC power output by the inverter 53 into DC power and supplies it to each part of the welding machine 51. Each part of the welding machine 51 operates using the DC power output by the rectifying circuit 54.

The DC/DC converter 34 is a circuit that converts the voltage value of the power output by the rectifying and smoothing circuit 52 to a predetermined voltage value, for example, a voltage value (15 V) higher than the output voltage value (12 V) of the auxiliary battery 8, and outputs the converted voltage. Diodes D1 and D2 form a selection circuit that selects the power to be supplied to the control circuit 31, and selects between power from the DC/DC converter 34 and power from the auxiliary battery 8 and supplies this to the control circuit 31 depending on whether the DC/DC converter 34 is operating.

For example, a user of vehicle 1 and welding machine 51 connects welding machine 51 to a stopped vehicle 1 via a power supply cable. When the power supply cable is connected to vehicle 1, rectifying and smoothing circuit 52 of welding machine 51 is electrically connected to vehicle 1's main battery 5, and the anode of diode D2 is electrically connected to vehicle 1's auxiliary battery 8. This causes power stored in auxiliary battery 8 to be supplied to control circuit 31 through diode D2, and control circuit 31 operates using this power supply. After exchanging various information regarding power supply with vehicle 1, for example, control circuit 31 operates inverter 53 to start supplying power to various components within welding machine 51. At the same time, vehicle 1 also exchanges various information regarding power supply with power supply device 3, for example, before starting power supply to welding machine 51.

Power from the vehicle 1's main battery 5 is supplied to the welding machine 51, and this power is then supplied to various parts of the welding machine 51 via the power supply device 3's rectifying and smoothing circuit 52, inverter 53, and rectifying circuit 54. The direct current power output by the rectifying and smoothing circuit 52 is supplied to the DC/DC converter 34, which converts the supplied power to a predetermined voltage value (a voltage value higher than the output voltage value of the auxiliary battery 8) and outputs it. The power output by the DC/DC converter 34 is supplied to the control circuit 31 via diode D1. As a result, the voltage value of the cathode of diode D2 becomes higher than the voltage value of the anode, so diode D2 is cut off and the power supply from the auxiliary battery 8 to the control circuit 31 is cut off.

The power supply device according to the fourth embodiment, configured as described above, exchanges power between a main battery 5 mounted on a vehicle 1 such as an electric automobile and an external device such as a welding machine 51. The welding machine 51, which functions as a power supply device, includes a first power path (i.e., a rectifying and smoothing circuit 52, an inverter 53, a rectifying circuit 54, and a power path (wiring, cable, etc.) between them) connecting to the main battery 5 and the external device (each part of the welding machine 51). The welding machine 51 also includes a second power path (i.e., a power path including a power path between the auxiliary battery 8 and the anode of diode D2, and a power path between the cathode of diode D2 and the control circuit 31) connecting to an auxiliary battery 8 mounted on the vehicle 1 and a control circuit 31. The welding machine 51 also includes a DC/DC converter 34 that receives power from the first power path and supplies it to the control circuit 31.

With these configurations, the welding machine 51 according to embodiment 4 can supply power from the auxiliary battery 8 of the vehicle 1 to the control circuit 31 to operate the control circuit 31 until power supply from the main battery 5 of the vehicle 1 begins. Furthermore, after power supply from the main battery 5 of the vehicle 1 begins, the welding machine 51 can supply power from the DC/DC converter 34 to the control circuit 31 to operate the control circuit 31, which is expected to prevent the auxiliary battery 8 from running out.

The welding machine 51 according to embodiment 4 may be configured to include a charging circuit 36 to charge the auxiliary battery 8, similar to the power supply device 3 according to embodiment 3. The welding machine 51 according to embodiment 4 may also be configured to include a voltage detection unit 37 to detect the output voltage value of the auxiliary battery 8, similar to the power supply device 3 according to embodiment 2, and control the operation of the DC/DC converter 34 in accordance with the detection result.

Note that the remaining configuration of the welding machine (power supply device) 51 according to embodiment 4 is the same as that of the power supply device 3 according to embodiments 1 to 3, so similar parts are given the same reference numerals and detailed descriptions are omitted.

The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is defined by the claims, not by the meaning described above, and is intended to include all modifications within the meaning and scope of the claims.

REFERENCE SIGNS LIST 1 vehicle 2 power receiving coil 3 power supply device 4 AC/DC converter 5 main battery 6 motor 7 DC/DC converter 8 auxiliary battery 9 control circuit 31 control circuit (control power supply circuit)
32 Rectification smoothing circuit 33 DC/AC converter 34 DC/DC converter (power supply circuit)
35 Capacitor 36 Charging circuit (power supply circuit)
37 Voltage detection unit 51 Welding machine 52 Rectification smoothing circuit 53 Inverter 54 Rectification circuit D1, D2 Diodes (power supply selection circuit)
SW Switch

Claims (1)

A power supply device that exchanges power between a main battery mounted on an electric vehicle and an external device,
a first power path leading to the main battery and the external device;
a second power path connected to an auxiliary battery and a control power supply circuit mounted on the electric vehicle;
a power supply circuit that receives power from the first power path and supplies power to the control power supply circuit ,
the power supply circuit is a circuit that outputs a constant current and charges the auxiliary battery via the second power path;
Power supply device.