阅读说明：本技术 车辆的电源系统 (Power supply system for vehicle ) 是由 武田光弘 于 2019-05-23 设计创作，主要内容包括：本发明提供车辆的电源系统,能向降压侧的电容器适当地进行充电,抑制系统故障。车辆的电源系统(1)具备：高电压蓄电池(21)；与高电压蓄电池(21)连接的第1逆变器(23)；与第1逆变器(23)连接的驱动电动机(RM)；将高电压蓄电池(21)的电压降压的高电压DCDC转换器(22)；与高电压DCDC转换器(22)连接的辅机(6)等；与辅机(6)等并联连接的电容器(C1)；取得电容器(C1)的充电状态的电流传感器(30)等；和基于电流传感器(30)等的取得值来控制高电压DCDC转换器(22)的VCUECU(8)。(The invention provides a power supply system for a vehicle, which can properly charge a capacitor on a voltage reduction side and suppress system failure. A power supply system (1) for a vehicle is provided with: a high-voltage battery (21); a 1 st inverter (23) connected to the high-voltage battery (21); a drive motor (RM) connected to the 1 st inverter (23); a high-voltage DCDC converter (22) for stepping down the voltage of the high-voltage battery (21); an auxiliary machine (6) connected to the high-voltage DCDC converter (22); a capacitor (C1) connected in parallel with the auxiliary machine (6) and the like; a current sensor (30) for acquiring the state of charge of the capacitor (C1); and a VCUECU (8) for controlling the high-voltage DCDC converter (22) on the basis of the acquired value of the current sensor (30) or the like.)

1. A power supply system for a vehicle, comprising:

a storage battery;

a first power converter connected to the battery;

a first driving motor connected to the first power converter;

a voltage converter that steps down a voltage of the battery;

an electrical device connected to the voltage converter;

a capacitor connected in parallel with the electrical device;

a charging state acquiring unit that acquires a charging state of the capacitor; and

and a control unit that controls the voltage conversion device based on the acquired value of the state-of-charge acquisition unit.

2. The vehicular power supply system according to claim 1,

the power supply system for a vehicle further includes:

a switching unit that switches a connection state and a blocking state of the storage battery,

the control unit controls the voltage conversion device based on the acquired value of the charging state acquisition unit when the switching unit switches from the blocking state to the connection state.

3. The vehicular power supply system according to claim 1 or 2,

the charging state acquisition means is current value acquisition means for controlling the voltage converter so that the value of the charging current to the capacitor becomes constant.

4. The vehicular power supply system according to claim 1 or 2,

the charging state acquiring unit is a voltage value acquiring unit,

controlling the voltage converter to increase a charging voltage value of the capacitor in a stepwise manner.

5. The vehicular power supply system according to any one of claims 1 to 4,

the electric device is a second driving motor connected via the second power converter.

6. The vehicular power supply system according to any one of claims 1 to 5,

the electrical device is an auxiliary machine.

7. The vehicular power supply system according to claim 6,

the auxiliary machine is as follows:

a dc charging section chargeable by the dc charging source;

an applied voltage value acquisition unit that acquires a voltage value applied to the dc charging unit by an external charging device;

a high-voltage charging path connected from the dc charging unit to between the voltage converter and the battery; and

a low-voltage charging path connected from the DC charging unit to the voltage converter and the second power converter,

the control unit controls the voltage conversion device based on the applied voltage acquisition value to adjust the voltage of the capacitor before the start of charging from the low-voltage charging path.

8. The vehicular power supply system according to any one of claims 1 to 7,

a switching element is arranged between a coil of a voltage converter for stepping down the voltage of a battery and an electric device connected to the voltage converter.

Technical Field

The present invention relates to a power supply system for a vehicle.

Background

In the past, there has been known a power supply system for a vehicle that supplies electric power from a battery to a plurality of drive motors via a single voltage converter. The voltage of the battery is converted into a predetermined voltage by a voltage converter, and each drive motor is driven by the converted voltage (patent document 1).

Disclosure of Invention

The invention aims to provide a power supply system of a vehicle, which can properly charge a capacitor on a voltage reduction side and restrain system faults.

(1) A vehicle power supply system (for example, a power supply system 1 described later) according to the present invention includes: a battery (for example, a high-voltage battery 21 described later); a first power converter (for example, a 1 st inverter 23 described later) connected to the battery; a first driving motor (e.g., a driving motor RM described later) connected to the first power converter; a voltage converter (for example, a high-voltage DCDC converter 22 described later) that steps down the voltage of the battery; electrical devices (for example, a 2 nd inverter 24, an auxiliary machine 6, and the like described later) connected to the voltage converter; a capacitor (e.g., capacitor C1 described later) connected in parallel with the electric device; a charging state acquisition unit (for example, a current sensor 30 and a voltage sensor 28 described later) that acquires a charging state of the capacitor; and a control unit (for example, VCUECU8 described later) that controls the voltage conversion device based on the acquired value of the state-of-charge acquisition unit.

According to the power supply system for a vehicle of (1), since the capacitor on the step-down side can be appropriately charged, a system failure can be suppressed.

(2) In the power supply system for a vehicle according to (1), a switching means (for example, a contactor 212p described later) for switching between a connection state and a disconnection state of the battery may be further provided, and the control means may control the voltage conversion device based on the acquired value of the state-of-charge acquisition means when the switching means switches from the disconnection state to the connection state.

According to the power supply system for a vehicle of (2), the capacitor on the voltage step-down side can be appropriately charged after the system is started, and the electrical device can be quickly put into a standby state.

(3) In the power supply system of the vehicle of (1) or (2), the charging state acquisition means may be current value acquisition means (for example, a current sensor 30 described later), and the voltage converter may be controlled so that the value of the charging current to the capacitor becomes constant.

According to the power supply system for a vehicle of (3), charging can be reliably performed within a desired charging time, and disconnection of the fuse can be suppressed.

(4) In the power supply system of the vehicle of (1) or (2), the charging state acquiring means may be voltage value acquiring means (for example, a voltage sensor 28 described later) and may control the voltage converter so that the charging voltage value of the capacitor is increased in stages.

According to the power supply system for a vehicle of (4), it is possible to appropriately perform charging up to a desired charging voltage and to suppress disconnection of the fuse.

(5) In the power supply system for a vehicle according to any one of (1) to (4), the electric device may be a second driving motor connected via a second power converter.

According to the power supply system for a vehicle of (5), a system including a plurality of motors having different drive voltages for one battery can be realized.

(6) In the power supply system for a vehicle according to any one of (1) to (5), the electric device may be an auxiliary device.

According to the power supply system for a vehicle of (6), it is possible to suppress a failure of the auxiliary machine while avoiding an unnecessary increase in cost such as a countermeasure for increasing the voltage of the auxiliary machine.

(7) The auxiliary devices in the power supply system of the vehicle in (6) may be: a dc charging unit (for example, a dc charging port 4 described later) chargeable by a dc charging source; an applied voltage value acquisition unit (for example, a voltage sensor 49 described later) that acquires a voltage value applied to the dc charging unit by the external charging device; a high-voltage charging path (not charging the battery via the VCU) connected between the voltage converter and the battery from the dc charging unit; and a low-voltage charging path (for charging the battery via the VCU) connected between the voltage converter and the second power converter from the dc charging unit, wherein the control unit controls the voltage conversion device based on the applied voltage acquisition value before starting charging from the low-voltage charging path, and adjusts the voltage of the capacitor.

According to the power supply system for a vehicle of (7), since the capacitor on the step-down side can be appropriately charged when the vehicle is charged from the external charging device, system failure can be suppressed.

(8) In the power supply system for a vehicle according to any one of (1) to (7), a switching element may be disposed between a coil of a voltage converter that steps down a voltage of a battery and an electric device (for example, a 2 nd inverter 24 and an auxiliary device 6 described later) connected to the voltage converter.

According to the power supply system for a vehicle of (8), it is possible to suppress application of a high-voltage to the electrical equipment side when the element of the upper arm of the voltage converter fails due to a short circuit.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a power supply system for a vehicle capable of appropriately charging a capacitor on the step-down side and suppressing a system failure.

Drawings

Fig. 1 is a diagram showing a power supply system of a vehicle according to embodiment 1 of the present invention.

Fig. 2 is a diagram showing the flow of a precharge current according to embodiment 1.

Fig. 3 is a diagram showing a timing chart of precharging in embodiment 1.

Fig. 4 is a diagram showing the flow of the precharge current according to embodiment 2.

FIG. 5 is a timing chart showing precharging in accordance with embodiment 2

Fig. 6 is a diagram showing a part of a power supply system of a vehicle according to embodiment 3.

Description of reference numerals

1 power supply system

21 high-voltage accumulator

23 st inverter

RM driving motor

22 high voltage DCDC converter

24 nd 2 inverter

Auxiliary machine of C1

6 capacitor

30 current sensor

28 Voltage sensor

8 VCUECU

Detailed Description

One embodiment of the present invention is described below with reference to the drawings.

Fig. 1 is a diagram showing a configuration of an electrically powered vehicle V (hereinafter simply referred to as a "vehicle") on which a power supply system 1 according to the present embodiment is mounted. In the present embodiment, a four-wheel drive electric vehicle including a drive motor is described as an example of the vehicle V, but the present invention is not limited to this. The power supply system according to the present invention can be applied to any vehicle that runs on electric power stored in a battery, such as a two-wheel drive electric vehicle, a hybrid vehicle, and a fuel cell vehicle.

The vehicle V includes a power supply system 1, a drive motor FM for front wheels FW, and a drive motor RM for rear wheels RW. The drive motors FM, RM mainly generate power for running of the vehicle V. Output shafts of the drive motors FM, RM are coupled to drive wheels FW, RW via a power transmission mechanism, not shown. Torque generated by the drive motors FM, RM by supplying electric power from the power supply system 1 to the drive motors FM, RM is transmitted to the drive wheels FW, RW via a power transmission mechanism, not shown, respectively, and the vehicle V travels by rotating the drive wheels FW, RW. The drive motors FM, RM function as generators during deceleration regeneration of the vehicle V. The electric power generated by the drive motor M is charged into the high-voltage battery 21 provided in the power supply system 1.

The power supply system 1 includes: a high-voltage circuit 2 provided with a high-voltage battery 21; a low-voltage circuit 3 having a lower voltage than the high-voltage battery 21; a dc charging unit 4 capable of supplying electric power to a drive motor FM for driving front wheels FW, a drive motor RM for driving rear wheels RW, the high-voltage circuit 2, and the low-voltage circuit 3; an ac charging unit 5 capable of supplying electric power to the low-voltage circuit 3; and an auxiliary machine 6 having a heater and the like.

The high-voltage circuit 2 includes: a high-voltage battery 21; a high-voltage DCDC converter 22 as a voltage converter; 1 st power lines 26p and 26n connecting the positive and negative poles of the high-voltage battery 21 and the low-voltage positive terminal 221 and the low-voltage negative terminal 222 of the high-voltage DCDC converter 22; the 1 st inverter 23 as a power converter; 2 nd power lines 27p and 27n connecting the high-voltage-side positive terminal 223 and the high-voltage-side negative terminal 224 of the high-voltage DCDC converter 22 and the dc input/output side of the 1 st inverter 23; and a secondary-2 side voltage sensor 29 that detects the voltage of the 2 nd power lines 27p, 27 n.

The high-voltage battery 21 is a secondary battery capable of performing both discharge for converting chemical energy into electric energy and charge for converting electric energy into chemical energy. The following description will be made of a case where a so-called lithium ion battery that performs charge and discharge by lithium ions moving between electrodes is used as the high-voltage battery 21, but the present invention is not limited to this.

High-voltage DCDC converter 22 is provided between 1 st power lines 26p, 26n and 2 nd power lines 27p, 27 n. The low-voltage-side positive terminal 221 and the low-voltage-side negative terminal 222 of the high-voltage DCDC converter 22 are connected to the high-voltage battery 21 via the 1 st power lines 26p and 26n, respectively, as described above. The high-voltage-side positive terminal 223 and the high-voltage-side negative terminal 224 of the high-voltage DCDC converter 22 are connected to the high-voltage battery 21 and the 1 st inverter 23 via the 2 nd power lines 27p and 27 n.

The high-voltage DCDC converter 22 is a bidirectional DCDC converter configured by combining a reactor L, a 1 st smoothing capacitor C1, high-arm (high arm) elements 225H and 226H, low-arm (low arm) elements 225L and 226L, a 2 nd smoothing capacitor C2, and a negative bus 227.

The high arm member 225H includes: known power switching elements such as IGBTs and MOSFETs; and a diode connected in parallel with the power switching element. The lower arm member 225L includes: known power switching elements such as IGBTs and MOSFETs; and a diode connected in parallel with the power switching element. These high-arm element 225H and low-arm element 225L are connected in series in this order between the high-voltage-side positive terminal 223 and the negative bus bar 227. In addition, the high-arm element 226H and the low-arm element 226L are also connected in series in this order between the high-voltage-side positive electrode terminal 223 and the negative bus bar 227.

The collector of the power switching element of the high-arm element 225H is connected to the high-voltage-side positive terminal 223, and the emitter thereof is connected to the collector of the low-arm element 225L. The emitter of the power switching element of the low-arm element 225L is connected to the negative bus bar 227. The forward direction of the diode provided in the high-arm element 225H is from the reactor L to the high-voltage-side positive terminal 223. The diode provided in the low-arm element 225L has a forward direction from the negative bus 227 toward the reactor L. One terminal of the reactor L is connected between the emitter of the high-arm element 225H and the collector of the low-arm element 225L, and the other terminal of the reactor L is connected between the emitter of the high-arm element 226H and the collector of the low-arm element 226L.

These high-arm elements 225H, 226H and low-arm elements 225L, 226L are respectively turned on or off by a gate drive signal generated by VCUECU 8.

The high-voltage DCDC converter 22 performs a voltage reduction function for bidirectional current by driving the elements 225H and 225L to be turned on and off in accordance with a gate drive signal generated at a predetermined timing from VCUECU 8. The step-down function is a function of stepping down a voltage applied to the high-voltage-side terminals 223 and 224 and outputting the voltage to the low-voltage-side terminals 221 and 222, and thus it is possible to flow a current from the 2 nd power lines 27p and 27n to the 1 st power lines 26p and 26n and also to flow a current from the 1 st power lines 26p and 26n to the 2 nd power lines 27p and 27 n. Hereinafter, the potential difference between the 1 st power lines 26p and 26n is referred to as the 1 st-side voltage V1. The potential difference between the 2 nd power lines 27p and 27n is referred to as a 2 nd side voltage V2.

The 1 st-order side voltage sensor 28 detects the 1 st-order side voltage V1, the 2 nd-order side sensor 29 detects the 2 nd-order side voltage V2, and sends a signal corresponding to the detected value to VCUECU 8.

The 1 st inverter 23 is, for example, a PWM inverter based on pulse width modulation including a bridge circuit configured by bridging a plurality of switching elements (for example, IGBTs), and has a function of converting dc power and ac power. The 1 st inverter 23 is connected to the terminal 231 of the 2 nd power line 27p and the terminal 232 of the 2 nd power line 27n on the dc input/output side thereof, and is connected to the coils of the U-phase, V-phase, and W-phase of the drive motor RM on the ac input/output side thereof. A terminal 233 which is grounded is provided between the terminals 231 and 232, a capacitor C4 is provided between the terminals 231 and 233, and a capacitor C5 is provided between the terminals 232 and 233. An active discharge controller 234 that controls discharge at the time of collision of the vehicle V and a capacitor C3 are provided in parallel with the capacitors C4, C5 between the 2 nd power lines 27p, 27 n.

The 1 st inverter 23 is configured by bridging a high-side U-phase switching element and a low-side U-phase switching element connected to U of the drive motor RM, a high-side V-phase switching element and a low-side V-phase switching element connected to V of the drive motor RM, and a high-side W-phase switching element and a low-side W-phase switching element connected to W of the drive motor RM for each phase.

The 1 st inverter 23 converts the direct-current power supplied from the high-voltage DCDC converter 22 into alternating-current power and supplies the alternating-current power to the drive motor RM, or converts the alternating-current power supplied from the drive motor RM into direct-current power and supplies the direct-current power to the high-voltage DCDC converter 22, by on/off driving the switching elements of the above-described phases in accordance with the gate drive signal generated by the motor ECU9 at a given timing. Further, the output of the drive motor FM for the front wheels FW and the output of the drive motor RM for the rear wheels RW may be larger.

The dc charging unit 4 is controlled by the PLC unit 7, is connected to a dc power supply, and charges the high-voltage battery 21 and supplies electric power to the primary side. The positive terminal of dc charging unit 4 is connected to 3 rd power line 41p, and the negative terminal of dc charging unit 4 is connected to 3 rd power line 41 n. The 3 rd power line 41p is connected to the terminal 211 of the 2 nd power line 27p via the terminal 411 and the contactor 42, and is connected to the terminal 301 of the 1 st power line 26p via the terminal 304. The 3 rd power line 41n is connected to the terminal 229 of the negative bus bar 227 via the terminals 412 and 413 in this order. In the 3 rd power line 41n, contactors 45 and 46 are disposed in parallel between the terminal 412 and the terminal 413, a protection fuse 44 for short-circuit is connected in series to the contactor 45 on the terminal 412 side, and a diode 47 in the forward direction from the terminal 413 toward the terminal 412 is connected in series to the contactor 46.

The high-voltage battery 21 is connected in parallel between the high-voltage DCDC converter 22 and the 1 st inverter 23 by a positive terminal connected to the 2 nd power line 27p and a negative terminal connected to the 2 nd power line 27 n. The high-voltage battery 21 is controlled in charging and discharging functions by the battery ECU 10. The high-voltage battery 21 is connected in series with the main contactor 212p and the contactor 211n in this order, and when these are turned on, a capacitor, not shown, is formed between the positive electrode terminal and the negative electrode terminal. The precharge contactor 211p and the precharge resistor 211r are connected in parallel to the main contactor 212 p. The precharge contactor 211p and the precharge resistor 211r are connected in series, and a current passing through the precharge contactor 211p is moderated by the precharge resistor 211 r. When the contactors 42 and 45 are turned on, a capacitor, not shown, is charged with a voltage applied from the dc charging unit 4. On the other hand, when the contactor 42 is opened, the precharge contactor 211p and the contactor 211n are turned on, the electric charge stored in the high-voltage battery 21 is discharged, and a current (hereinafter referred to as "precharge") is supplied to the 1 st inverter 23 or the high-voltage DCDC converter 22. When the precharge contactor 211p is opened and the main contactor 212p and the contactor 211n are closed, a current is supplied to the 1 st inverter 23 or the high-voltage DCDC converter 22.

The low-voltage circuit 3 includes: 1 st power lines 26p and 26n connecting the high-voltage-side positive electrode terminal 221 and the high-voltage-side negative electrode terminal 222 of the high-voltage DCDC converter 22 and the dc input/output side of the 2 nd inverter 24; a 1 st-side voltage sensor 28 that detects the voltage of the 1 st power lines 26p, 26 n; a 1 st-order side current sensor 30 capable of detecting a current to the capacitor C1; an auxiliary machine 6; and an ac charging unit 5.

The 2 nd inverter 24 has the same configuration as the 1 st inverter 23, and has a function of converting dc power and ac power. The 2 nd inverter 24 is connected to the terminal 241 of the 1 st power line 26p and the terminal 242 of the 1 st power line 26n on the dc input/output side thereof, and is connected to the coils of the U-phase, V-phase, and W-phase of the drive motor RM on the ac input/output side thereof. A capacitor C6 is provided between the terminals 241 and 242. An active discharge controller 244 that controls discharge at the time of a collision of the vehicle V, and capacitors C7 and C8 are provided in parallel to the capacitor C6 on the high-voltage DCDC converter 22 side. A terminal 243 grounded is provided between the terminal 245 of the 1 st power line 26p and the terminal 246 of the 1 st power line 26n, a capacitor C7 is provided between the terminal 245 and the terminal 243, and a capacitor C8 is provided between the terminal 243 and the terminal 246.

The 2 nd inverter 24 converts the direct-current power supplied from the high-voltage DCDC converter 22 into alternating-current power and supplies to the drive motor FM, or converts the alternating-current power supplied from the drive motor FM into direct-current power and supplies to the high-voltage DCDC converter 22, by on/off driving the switching elements of each phase in accordance with the gate drive signal generated by the motor ECU11 at a given timing.

The AC charging unit 5 includes an AC charger 53 having a function of converting an AC current into a dc current, and an output current thereof is supplied to the 1 st side. The input and output of the current to the AC charger 53 are controlled by the charging ECU 54. The positive-side terminals of the AC charging unit 5 and the AC charger 53 are connected to the 5 th power line 51p, and the negative-side terminals of the AC charging unit 5 and the AC charger 53 are connected to the 5 th power line 51 n. The 5 th power line 51p is connected to the terminal 301 of the 1 st power line 26p via the fuse 51, the terminal 304, and the terminal 302. The 5 th power line 51n is connected to the terminal 303 of the 1 st power line 26n via the terminal 228.

The auxiliary machine 6 includes, for example, an electric compressor, a heater, and the like. The positive terminal of the smoothing capacitor C9 provided in the auxiliary device 6 is connected to the 4 th power line 61p, and the negative terminal of the capacitor C9 is connected to the 4 th power line 61 n. The 4 th power line 61p is connected to the terminal 301 of the 1 st power line 26p via the fuse 61 and the terminal 302, and the 4 th power line 61n is connected to the terminal 303 of the 1 st power line 26n via the terminal 228. That is, the auxiliary machine 6 is connected in parallel between the high-voltage DCDC converter 22 and the 2 nd inverter 24.

Therefore, the dc charging unit 4 is connected to the high-voltage source, charges the high-voltage battery 21, and applies a voltage between the 1 st power lines 26p and 26n to supply electric power. That is, in the high-voltage charging path formed by turning on the contactors 42 and 45, a high voltage is applied between the terminals 211 and 229. In the low-voltage charging path formed by the contactors 43, 45 being turned on, the low voltage stepped down by the DCDC converter 22 is applied between the terminals 229, 301.

The precharge operation according to embodiment 1 will be described with reference to fig. 2 and 3. In embodiment 1, when main contactor 212p, which is a switching means for switching between the connection state and the disconnection state of high-voltage battery 21, is switched from the disconnection state to the connection state, VCUECU8 controls high-voltage DCDC converter 22 based on the value obtained by current sensor 30, as indicated by arrow S in fig. 2.

Fig. 3 is a timing chart of precharging in embodiment 1. When the ignition is turned on at time t0, VCUECU8 starts controlling the electric power. The precharge is started at time t 1. When the contactor 211p is turned on, the VCUECU8 causes current to flow in the capacitors C2 and C3 on the path indicated by the arrow a, and the voltage value V2 gradually increases from the time t 1. At time t2, VCUECU8 brings main contactor 212p into the on state. When the switches of the high-arm elements 225H and 226H are turned on at time t3, electric charges flow into the capacitors C1, C6, C7, C8, and C9 on the path indicated by arrow B in fig. 3. When VCUECU8 controls current I1 flowing in capacitor C1 to be constant based on the value obtained by current sensor 30, voltage V1 of capacitor C1 gradually rises. When the capacitor C1 is in the fully charged state at time t4, the voltage value V1 reaches a constant value and the value of the current I1 also becomes substantially 0. The value of the charging current I1 may be a predetermined given value, or may be set to be smaller as the ambient temperature, for example, the external atmospheric temperature or the fuse temperature, is higher.

As described above, according to the power supply system for a vehicle according to embodiment 1, the high-voltage DCDC converter 22 is controlled so that the value of the charging current to the capacitor C1 in the current sensor 30 becomes constant, whereby disconnection of the fuse can be suppressed, and charging of the contactor after system start can be appropriately performed. As a result, the electric device can be quickly brought into a standby state.

The precharge operation according to embodiment 2 will be described with reference to fig. 4 and 5. The circuit configuration of the power supply system 1 is the same as that of embodiment 1, and therefore, the description thereof is omitted. The difference from embodiment 1 is a control method of precharging performed by VCUECU 8.

In embodiment 2, when the contactor 211p, which is a switching means for switching between the connection state and the disconnection state of the high-voltage battery 21, is switched from the disconnection state to the connection state, the VCUECU8 controls the high-voltage DCDC converter 22 based on the acquired values of the voltage sensors 28 and 29 so that the charging voltage value of the capacitor C1 increases in a stepwise manner, as indicated by an arrow S in fig. 4.

Fig. 5 is a timing chart of precharging in embodiment 2. If the ignition is turned on at time t0, VCUECU8 starts the control of the electric power. The precharge is started at time t 1. When the contactor 211p is turned on, the VCUECU8 causes current to flow into the capacitors C2 and C3 on the path indicated by the arrow a, and the voltage value V2 gradually increases from the time t 1. At time t2, VCUECU8 brings main contactor 212p into the on state. When the switches of the high-arm elements 225H and 226H are turned on at time t3, electric charges flow into the capacitors C1, C6, C7, C8, and C9 on the path indicated by arrow B in fig. 4. The VCUECU8 controls the current I1 flowing in the capacitor C1 based on the acquired values of the voltage sensors 28 and 29, so that the capacitor C1 rises in stages. When the voltage value V1 of the capacitor C1 increases in a stepwise manner and the capacitor C1 becomes a fully charged state at time t4, the voltage value V1 reaches a constant value and the value of the current I1 also becomes substantially 0.

As described above, according to the power supply system for a vehicle in embodiment 2, since the current smoothly flows to the capacitor C1, damage to the element can be prevented and disconnection of the fuse can be suppressed, and thus charging can be appropriately performed up to a desired charging voltage.

Fig. 6 is a diagram showing a part of a power supply system of a vehicle according to embodiment 3. The circuit configuration of embodiment 3 is obtained by adding a switching element 400 to the circuit configuration of embodiment 1. Switching element 400 is disposed between reactor L of high-voltage DCDC converter 22 that steps down the voltage of high-voltage battery 21, and 2 nd inverter 24, auxiliary machine 6, and ac charging unit 5 connected to high-voltage DCDC converter 22. As shown in fig. 6, switching element 400 such as an IGBT is connected between reactor L and terminal 221 in the direction in which the collector is connected to terminal 221.

Switching element 400 may also be controlled by VCUECU8 as part of DCDC converter 22. In this case, VCUECU8 can moderate the current from high-voltage battery 21 by turning on and off switching element 400, and can smoothly charge capacitor C1. The switching element 400 can suppress application of a high voltage to the primary side to which the front motor ECU11, auxiliary equipment, and the like are connected, for example, at the time of an element short-circuit failure of the upper arm of the high-voltage DCDC converter 22. As described above, according to the power supply system for a vehicle according to embodiment 3, it is possible to prevent a failure of the power supply system 1.

Further, the devices referred to as auxiliary machines in embodiments 1 to 3 may be a dc charging unit 4 chargeable by a dc charging source, a voltage sensor 49 for acquiring a voltage value applied to the dc charging unit 4 by an external charging device, a high-voltage charging path connected from the dc charging unit 4 to between the high-voltage DCDC converter 22 and the high-voltage battery 21, and a low-voltage charging path connected from the dc charging unit 4 to between the high-voltage DCDC converter 22 and the 2 nd inverter 24. VCUECU8 may control high-voltage DCDC converter 22 to adjust the voltage of capacitor C1 based on the value obtained by voltage sensor 49 before the start of charging from the low-voltage charging path. When the vehicle is charged from the external charging apparatus, the capacitor C1 on the step-down side can be appropriately charged, and therefore, a system failure can be suppressed.

According to the power supply system 1 of the embodiments 1 to 3 as described above, it is possible to suppress a failure of the auxiliary unit 6 while avoiding an unnecessary increase in cost such as a response to a high voltage of the auxiliary unit 6.

The present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within a range that can achieve the object of the present invention are included in the present invention.