JP2020198716A - Vehicle drive device - Google Patents

Abstract

To provide a vehicle drive device that supplies a plurality of magnitudes of power source voltages for vehicle travel by a lightweight and simple constitution.SOLUTION: A vehicle drive device 10 comprises: a power source 3 in which a battery 18 and a capacitor 22 for the power source are serially connected together; a main drive motor 16 that is provided with a voltage of the battery 18; an auxiliary drive motor 20 that is provided with a total voltage (Vin) of the battery 18 and the capacitor 22 for the power source; a charging circuit 19; and a control circuit 24 for controlling the discharge and charge of the power source 3. The control circuit 24 controls the discharge and charge of the battery 18 and the capacitor 22 by operating switches SW1 to SW4 of the charging circuit 19.SELECTED DRAWING: Figure 4

Description

The present invention relates to a vehicle drive device, and more particularly to a vehicle drive device for driving a vehicle by supplying a power supply voltage for traveling a plurality of vehicles having different sizes.

Japanese Patent Application Laid-Open No. 2015-136263 (Patent Document 1) describes a vehicle control circuit. This vehicle control circuit includes a generator driven by an engine, a battery for supplying power to an electric load, a capacitor connected in parallel with the battery, and a DC / DC converter. Further, this device is provided with a 12V power line connected to a battery and a 25V power line connected to a capacitor, and a DC / DC converter is provided between these two power lines. There is.

In the device of Patent Document 1, a 12V power line and a 25V power line each supply the corresponding electric load. The capacitor is charged by the generator while the vehicle is running. Further, in this device, the DC / DC converter can convert the power of the 25V power line into the power of 12V and supply it to the power line of 12V.

Japanese Unexamined Patent Publication No. 2015-136263

However, the vehicle control circuit of Patent Document 1 simply supplies two power supply voltages having different sizes corresponding to the voltages of the capacitor and the battery to the in-vehicle electric load. Therefore, if a higher voltage power source is required to drive the vehicle, another power storage device (for example, a capacitor with a higher maximum voltage (withstand voltage) or another battery with a higher rated voltage) should be adopted. become. In this case, there arises a problem of increased weight and cost of the vehicle.

Therefore, an object of the present invention is to provide a vehicle drive device that supplies power supply voltages for traveling vehicles of a plurality of sizes in a lightweight and simple configuration.

In order to solve the above-mentioned problems, the present invention provides a vehicle drive device mounted on a vehicle, a power source in which a rechargeable battery and a power supply capacitor are connected in series, and a battery voltage. A first vehicle drive motor, a second vehicle drive motor that provides the total voltage of the battery and the power supply capacitor, a charging circuit connected to the power supply, and a control that controls charging / discharging of the power supply via the charging circuit. The power supply capacitor has a first terminal and a second terminal, and the charging circuit includes a charging capacitor having a first terminal and a second terminal, and a first charging capacitor. The first switch for electrically connecting and disconnecting the terminal of the power supply capacitor and the first terminal of the power supply capacitor, and the first terminal of the charging capacitor and the second terminal of the power supply capacitor are electrically connected and disconnected. A second switch for disconnecting, a third switch for electrically connecting and disconnecting the second terminal of the charging capacitor and the positive terminal of the battery, and a second terminal of the charging capacitor and the battery. A fourth switch for electrically connecting and disconnecting the negative electrode terminal is provided, and the control circuit operates the first, second, third and fourth switches to charge the battery and the power supply capacitor. It is characterized in that it is configured to control the discharge.

In the present invention configured as described above, the power supply includes a battery and a capacitor connected in series, and includes at least a first power line connected to the capacitor and a second power line 5b connected to the battery. ing. The first power line and the second power line can provide different power supply voltages. The first power line drives the second vehicle drive motor, and the second power line drives the first drive motor. As described above, in the present invention, a plurality of power supply voltages can be supplied with a simple and simple configuration. Further, in the present invention, since the power supply is configured by connecting the battery and the power supply capacitor in series, the charging circuit can be simply configured by four electric switches and a charging capacitor as a charge buffer. The control circuit can easily charge and discharge electric charges between the battery and the power supply capacitor by opening and closing these four electric switches.

In the present invention, preferably, the rated voltage of the power supply capacitor is larger than the rated voltage of the battery. According to the present invention configured as described above, when the power source is charged by an external power source, even if the rated voltage of the battery is smaller than the lower limit voltage of the external power source, a power supply capacitor having a higher rated voltage than the battery is connected in series. As a result, the input voltage value of the vehicle can be easily maintained larger than the lower limit voltage.

In the present invention, preferably, the positive terminal of the battery and the second terminal of the power supply capacitor are connected, and the power supply is connected in parallel to the series circuit of the first, second, third and fourth switches. The charging capacitor is connected in parallel to the series circuit of the second switch and the third switch, and the connection point between the second switch and the third switch is connected to the positive terminal of the battery.

In the present invention, preferably, the control circuit closes the first and third switches and opens the second and fourth switches to remove a part of the electric charge stored in the power supply capacitor. The first step of storing in the charging capacitor, the first and third switches are opened and the second and fourth switches are closed, and the battery is charged by the electric charge stored in the charging capacitor. The charging circuit is controlled so as to repeat the two steps and multiple times.
According to the present invention configured as described above, the battery can be charged by discharging the electric charge of the power supply capacitor to the battery via the charging circuit. At this time, for example, by supplying charging power to the power supply capacitor from an external power source, the battery and the power supply capacitor can be substantially charged at the same time by the external power source.

In the present invention, preferably, the control circuit opens the first and third switches and closes the second and fourth switches to charge a part of the electric charge stored in the battery. The third step of storing in the capacitor, the first and third switches are closed and the second and fourth switches are opened, and the power supply capacitor is charged by the electric charge stored in the charging capacitor. The charging circuit is controlled so as to repeat the four steps and multiple times.
According to the present invention configured as described above, the power supply capacitor can be charged by discharging the electric charge of the battery to the power supply capacitor via the charging circuit.

In the present invention, preferably, the power supply capacitor is configured so that the charge that can be stored is less than the charge that can be stored in the battery.
According to the present invention configured as described above, when the power supply capacitor is charged by the battery, the total voltage of the battery and the power supply capacitor can be increased. Therefore, when the total voltage is lower than the lower limit voltage of the external power supply, the total voltage can be boosted to enable external charging.

According to the present invention, it is possible to provide a vehicle drive device that supplies power supply voltages for traveling vehicles of a plurality of sizes in a lightweight and simple configuration.

It is a layout figure of the vehicle equipped with the vehicle drive device according to the embodiment of this invention. It is a figure which shows the relationship between the output of each motor of the vehicle drive device and the vehicle speed by embodiment of this invention. It is an electric block diagram of the vehicle drive device by embodiment of this invention. It is explanatory drawing of the electric circuit of the battery, the capacitor and the charging circuit of the vehicle drive device according to the embodiment of this invention. It is a processing flow of the external charge processing of the vehicle drive device according to the embodiment of this invention. It is a processing flow of pre-charging information processing in the external charging processing of a vehicle drive device according to the embodiment of this invention. It is a processing flow of the charging process in the external charging process of the vehicle drive device according to the embodiment of the present invention. It is a time chart which shows the displacement of the current and voltage at the time of external charging of the vehicle drive device by embodiment of this invention. It is a figure which shows the opening / closing position of the electric switch, and the flow of electric current in each stage at the time of external charging of the vehicle drive device by embodiment of this invention. It is a processing flow of the capacitor charge processing of the vehicle drive device by embodiment of this invention. It is a time chart which shows the displacement of the current and voltage at the time of the capacitor charging process of the vehicle drive device by embodiment of this invention. It is a figure which shows the opening / closing position of an electric switch, and the flow of an electric current in each stage at the time of the capacitor charging process of the vehicle drive device by embodiment of this invention. It is a processing flow of the capacitor discharge processing of the vehicle drive device according to the embodiment of this invention. It is a time chart which shows the displacement of the current and voltage at the time of the capacitor discharge processing of the vehicle drive device by embodiment of this invention. It is a figure which shows the opening / closing position of the electric switch, and the flow of electric current in each stage at the time of the capacitor discharge processing of the vehicle drive device by embodiment of this invention.

Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings. First, the configuration of the vehicle drive device according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a layout diagram of a vehicle equipped with a vehicle drive device, and FIG. 2 is a diagram showing the relationship between the output of each motor of the vehicle drive device and the vehicle speed.

As shown in FIG. 1, in the vehicle 1 equipped with the vehicle drive device 10 according to the embodiment of the present invention, the engine 12 which is an internal combustion engine is mounted in the front part of the vehicle in front of the driver's seat, and the main drive wheels. It is a so-called FR (Front engine, Rear drive) vehicle that drives a pair of left and right rear wheels 2a.

The vehicle drive device 10 according to the embodiment of the present invention includes a main drive motor 16 for driving a pair of rear wheels 2a, an auxiliary drive motor 20 for driving a pair of front wheels 2b, and a power supply 3 (battery 18) for supplying electric power to these motors. , Power supply capacitor 22), charging circuit 19, and control circuit 24.

The engine 12 is an internal combustion engine for generating a driving force for the rear wheels 2a, which are the main driving wheels of the vehicle 1. In the present embodiment, an in-line 4-cylinder engine is adopted as the engine 12, and the engine 12 arranged at the front of the vehicle 1 drives the rear wheels 2a via the power transmission mechanism 14.

The power transmission mechanism 14 is configured to transmit the driving force generated by the engine 12 and the main drive motor 16 to the rear wheels 2a, which are the main drive wheels. As shown in FIG. 1, the power transmission mechanism 14 includes a propeller shaft 14a, which is a power transmission shaft connected to the engine 12 and the main drive motor 16, and a transmission 14b, which is a transmission.

The main drive motor 16 is an electric motor for generating a driving force for the main drive wheels, is provided on the vehicle body of the vehicle 1, is arranged behind the engine 12 and adjacent to the engine 12. Further, an inverter 16a is arranged adjacent to the main drive motor 16, and the inverter 16a converts the DC voltage of the battery 18 into an AC voltage and supplies the DC voltage to the main drive motor 16. Further, as shown in FIG. 1, the main drive motor 16 is connected in series with the engine 12, and the driving force generated by the main drive motor 16 is also transmitted to the rear wheels 2a via the power transmission mechanism 14. Further, in the present embodiment, as the main drive motor 16, a 25 kW permanent magnet electric motor (permanent magnet synchronous motor) driven at a relatively low voltage (48 V or less in this example) is adopted.

The auxiliary drive motor 20 is provided on each of the front wheels 2b so as to generate a driving force on the front wheels 2b, which are the auxiliary drive wheels. Further, the auxiliary drive motor 20 is an in-wheel motor, and is housed in each of the wheels of the front wheels 2b. Further, the DC voltage of the capacitor 22 is converted into an AC voltage by the inverter 20a arranged in the tunnel portion 15 and supplied to each auxiliary drive motor 20. Further, in the present embodiment, the auxiliary drive motor 20 is not provided with a speed reducer which is a reduction mechanism, the driving force of the auxiliary drive motor 20 is directly transmitted to the front wheels 2b, and the wheels are directly driven. Further, in the present embodiment, 17 kW induction motors driven by a relatively high voltage (120 V or less in this example) are adopted as the auxiliary drive motors 20, respectively.

The power supply 3 is configured by connecting the battery 18 and the capacitor 22 in series (see FIG. 3). That is, the negative electrode terminal of the battery 18 is connected to the vehicle body ground G of the vehicle 1, and the positive electrode terminal of the battery 18 and the negative electrode terminal of the capacitor 22 are connected.

The battery 18 is a capacitor for storing electrical energy that mainly operates the main drive motor 16. In this embodiment, a 48V, 3.5kWh lithium ion battery (LIB) is used as the battery 18. Specifically, the battery 18 is configured by connecting a plurality of battery cells 18a (see FIG. 3) in series. In the present embodiment, the rated voltage of one battery cell 18a is about 3V, and 12 battery cells 18a are connected in series.

The capacitor 22 is a power storage device for supplying electric power to the auxiliary drive motor 20 provided on each of the front wheels 2b of the vehicle 1. The capacitor 22 is arranged at the rear portion of the vehicle 1 at a position substantially symmetrical with the plug-in type charging circuit 19. In the present embodiment, the capacitor 22 has a withstand voltage of 72 V and a capacitance of about several farads. The sub-drive motor 20 is a motor driven at a voltage higher than that of the main drive motor 16, and is mainly driven by the electric energy stored in the capacitor 22.

The charging circuit 19 is electrically connected to the battery 18 and the capacitor 22. The charging circuit 19 charges the battery 18 and the capacitor 22 with the regenerative power of the main drive motor 16 and the sub drive motor 20 and the power supplied from an external power source 17 such as a charging stand connected to the power supply port 23. It is configured in.

The power supply port 23 is a connector provided on the rear side surface of the vehicle 1 and is electrically connected to the charging circuit 19. The connector of the power supply port 23 is configured to be connectable to a plug of an electric cable 17a extending from an external power source 17 such as a charging stand, and power is supplied to the charging circuit 19 via the power supply port 23. As described above, the vehicle drive device 10 of the present embodiment is configured to be able to charge the battery 18 and the capacitor 22 by connecting the external power source 17 that supplies DC power to the power supply port 23 via the electric cable 17a. ing.

The control circuit 24 is configured to control the engine 12, the main drive motor 16, and the sub-drive motor 20 to execute the electric motor traveling mode and the internal combustion engine traveling mode. Further, the control circuit 24 is configured to control the charging circuit 19 to charge and discharge the battery 18 and the capacitor 22. Specifically, the control circuit 24 can be configured by a microprocessor, a memory, an interface circuit, a program for operating these (these are not shown above), and the like.

Next, with reference to FIG. 2, the relationship between the vehicle speed in the vehicle drive device 10 and the output of each motor is shown. In FIG. 2, the output of the main drive motor 16 is indicated by a broken line, the output of one auxiliary drive motor 20 is indicated by an alternate long and short dash line, and the total output of the two auxiliary drive motors 20 is indicated by an alternate long and short dash line. The total is shown by the solid line. In FIG. 2, the speed of the vehicle 1 is shown on the horizontal axis, and the output of each motor is shown on the vertical axis. However, since there is a certain relationship between the speed of the vehicle 1 and the rotation speed of the motor, the horizontal axis is used. Even when the motor rotation speed is used, the output of each motor draws the same curve as in FIG.

In the present embodiment, since the permanent magnet motor is adopted as the main drive motor 16, as shown by the broken line in FIG. 2, the output of the main drive motor 16 is large in the low vehicle speed range where the motor rotation speed is low, and the vehicle speed is high. As the speed increases, the motor output that can be output decreases. That is, in the present embodiment, the main drive motor 16 is driven at about 48 V, outputs a torque of about 200 Nm, which is the maximum torque up to about 1000 rpm, and the torque decreases as the rotation speed increases at about 1000 rpm or more. Further, in the present embodiment, the main drive motor 16 is configured to obtain a continuous output of about 20 kW in the lowest speed range and a maximum output of about 25 kW.

On the other hand, since the induction motor is used for the auxiliary drive motor 20, as shown by the alternate long and short dash line in FIG. 2, the output of the auxiliary drive motor 20 is extremely small in the low vehicle speed range, and the vehicle speed is high. The output increases as the speed increases, and the motor output decreases after the maximum output is obtained at a vehicle speed of about 130 km / h. In the present embodiment, the auxiliary drive motor 20 is driven at about 120 V, and is configured to obtain an output of about 17 kW per unit at a vehicle speed of about 130 km / h and a total output of about 34 kW for the two units. That is, in the present embodiment, the auxiliary drive motor 20 has a peak torque curve at about 600 to 800 rpm, and a maximum torque of about 200 Nm can be obtained.

The solid line in FIG. 2 shows the total output of the main drive motor 16 and the two sub drive motors 20. As is clear from this graph, in the present embodiment, a maximum output of about 53 kW is obtained at a vehicle speed of about 130 km / h, and this maximum output at this vehicle speed satisfies the running conditions required in the WLTP test. be able to. In the solid line of FIG. 2, the output values of the two sub-drive motors 20 are added up even in the low vehicle speed range, but in reality, each sub-drive motor 20 is not driven in the low vehicle speed range. That is, when starting and in the low vehicle speed range, the vehicle is driven only by the main drive motor 16, and only when a large output is required in the high vehicle speed range (when accelerating the vehicle 1 in the high vehicle speed range, etc.), two vehicles are used. The auxiliary drive motor 20 generates an output. In this way, by using the induction motor (secondary drive motor 20) capable of generating a large output in the high rotation range only in the high speed range, when necessary while suppressing the increase in vehicle weight to a low level (predetermined speed or higher). Sufficient output can be obtained when accelerating at.

Next, with reference to FIG. 3, the electrical configuration of the vehicle drive device 10 according to the embodiment of the present invention will be described. FIG. 3 is an electric block diagram of the vehicle drive device.

In this embodiment, the vehicle drive device 10 is configured to supply three different magnitudes of power supply voltage. That is, the vehicle drive device 10 has a first power line 5a that supplies a maximum 120V voltage, a second power line 5b that supplies a maximum 48V voltage, and a third power line 5c that supplies a maximum 12V voltage. It is provided.

The first power line 5a is connected to the positive electrode terminal of the capacitor 22, and supplies a 120 VDC voltage to the auxiliary drive motor 20 via the inverter 20a. That is, a potential difference of 120 VDC at the maximum is generated between the positive electrode terminal of the capacitor 22 and the vehicle body ground G of the vehicle 1 by the total voltage of the voltage between the terminals of the battery 18 and the voltage between the terminals of the capacitor 22. The inverter 20a connected to each sub-drive motor 20 drives the sub-drive motor 20, which is an induction motor, after converting the outputs of the battery 18 and the capacitor 22 into alternating current.

The second power line 5b is connected to the positive electrode terminal of the battery 18 and supplies a 48 VDC voltage to the main drive motor 16 via the inverter 16a. That is, a potential difference of 48 VDC at the maximum is generated between the positive electrode terminal of the battery 18 and the vehicle body ground G of the vehicle 1 due to the voltage between the terminals of the battery 18. The inverter 16a converts the output of the battery 18 into alternating current and then drives the main drive motor 16 which is a permanent magnet electric motor.

The third power line 5c is connected to the positive electrode terminal of a specific battery cell 18a among the plurality of battery cells 18a connected in series. That is, a potential difference of about 12 VDC is generated between the positive electrode terminal of the specific battery cell 18a and the vehicle body ground G of the vehicle 1 by a series connection circuit of a predetermined number (4 in this example) of the battery cells 18a. Will be done. The third power line 5c is an accessory power source and supplies a 12 VDC voltage to the electric load 28 of the vehicle 1 via the switch 18c. The electric load is an in-vehicle electric device (for example, an air conditioner, an audio device, etc.).

In this way, the main drive motor 16 is driven by about 48 V, which is the reference output voltage of the battery 18. Further, since the auxiliary drive motor 20 is driven by the total voltage obtained by adding the output voltage of the battery 18 and the voltage between the terminals of the capacitor 22, it is driven by a maximum voltage of 120 V, which is higher than 48 V. The electric energy supplied to the auxiliary drive motor 20 is stored in the capacitor 22, and the auxiliary drive motor 20 is always driven by the electric power supplied through the capacitor 22.

As shown in FIG. 3, the charging circuit 19 is connected to the positive electrode terminal of the capacitor 22, the connection point N0 between the positive electrode terminal of the battery 18 and the negative electrode terminal of the capacitor 22, and the vehicle body ground G. The control circuit 24 executes the charging process of the battery 18 and the capacitor 22 by using the charging circuit 19 at a predetermined time (when the motor is regenerated and when the external power source 17 is used for external charging).

The control circuit 24 monitors the voltage and current of the first power line 5a, the second power line 5b, and the third power line 5c by using a plurality of voltage sensors and a plurality of current sensors (not shown). Further, the control circuit 24 uses these voltage values and current values to determine the voltage between the terminals of the battery 18 (hereinafter referred to as “battery voltage”), the voltage between terminals of the capacitor 22 (hereinafter referred to as “capacitor voltage”), and these. The state of charge (SOC) is calculated.

When the vehicle 1 is decelerating or the like, the main drive motor 16 and each sub drive motor 20 function as a generator to regenerate the kinetic energy of the vehicle 1 to generate electric power. The electric power regenerated by the main drive motor 16 is stored in the battery 18, and the electric power regenerated by each sub drive motor 20 is mainly stored in the capacitor 22.

Further, in the case of charging using the external power supply 17, when the external power supply 17 is connected to the power supply port 23, the charging voltage of the external power supply 17 is applied to the charging circuit 19 and the capacitor 22, and the battery 18 and the capacitor 22 are charged. Will be possible.

Since the capacitance of the capacitor 22 is relatively small, the capacitor voltage rises relatively rapidly when the capacitor 22 is charged by motor regeneration and external charging. When the capacitor voltage reaches a predetermined voltage due to charging, the control circuit 24 controls the charging circuit 19 and charges the battery 18 using the electrostatic energy (charge) stored in the capacitor 22. As a result, the capacitor voltage drops, so that the capacitor 22 can be charged again. By repeating such processing, it is possible to gradually boost the battery voltage. That is, the electric power regenerated by each sub-drive motor 20 and the electric power from the external power source 17 are temporarily stored in the capacitor 22 and then charged into the battery 18.

Further, in general, when the external power supply 17 such as a charging stand is connected to the power supply port of the vehicle, it acquires the voltage of the vehicle (that is, the voltage to ground of the power supply port), and this voltage is a predetermined lower limit voltage (for example, If it is less than 50V), the charging process is not executed to ensure safety.

In the present embodiment, the rated voltage (48V) of the battery 18 is set to a voltage lower than the lower limit voltage (50V), but the external power supply 17 is the total voltage of the battery voltage Vbatt and the capacitor voltage Vcap (that is, the first voltage). 1 The voltage of the power line 5a) is acquired as the voltage of the vehicle 1. Therefore, in the present embodiment, if the total voltage is equal to or higher than the lower limit voltage, the external power supply 17 starts the charging process and the control circuit 24 controls the charging circuit 19 regardless of the magnitude of the battery voltage Vbatt. , Battery 18 and capacitor 22 can be charged.

On the other hand, if the total voltage (= Vbatt + Vcap) is less than the lower limit voltage when the external power supply 17 is connected to the power supply port 23, the external power supply 17 does not start the charging process. In this case, the control circuit 24 controls the charging circuit 19 and boosts the capacitor voltage by using a part of the electric energy stored in the battery 18. At this time, since the battery 18 has a large amount of stored charges, the battery voltage hardly drops. As a result, the total voltage can be boosted to the lower limit voltage or higher.

Further, when the capacitor voltage becomes lower than the predetermined voltage due to the discharge of the capacitor 22 even when the capacitor 22 is not charged (that is, while the vehicle 1 is running), the control circuit 24 supplies power from the capacitor 22 to the auxiliary drive motor 20. Previously, the power of the battery 18 can be used to charge the capacitor 22.

In the present specification, the rated voltage of the battery 18 means the maximum value (full charge voltage) of the operating voltage under general conditions, and the rated voltage of the capacitor 22 is the maximum given to the capacitor 22. It means the voltage of (full charge voltage). Further, the average operating voltage when the battery is discharged under general conditions is called the nominal voltage of the battery. Further, the rated voltage (48V) of the battery 18 is set lower than the rated voltage (72V) of the capacitor 22, but the electric charge (electric energy: coulomb) that can be stored in the battery 18 is the electric charge that can be stored in the capacitor 22. It is configured to be much more than.

Next, the charging process of the vehicle driving device 10 according to the embodiment of the present invention will be described with reference to FIGS. 4 to 11. FIG. 4 is an explanatory diagram of an electric circuit of a battery, a capacitor, and a charging circuit. As shown in FIG. 4, a switch SWbatt is connected to the positive electrode terminal of the battery 18, a switch SWcap is connected to the positive electrode terminal of the capacitor 22, and the battery 18 and the capacitor 22 can be connected or disconnected. ..

The charging circuit 19 is connected in parallel to the battery 18 and the capacitor 22 connected in series. The charging circuit 19 contains four switches connected in series, and the switches SW1, SW2, SW3, and SW4 are connected in this order. One end of the switch SW1 is connected to the positive electrode terminal of the capacitor 22, and one end of the switch SW4 is connected to the negative electrode terminal (vehicle body ground G) of the battery 18. Further, the connection point N2 of the switches SW2 and SW3 is connected to the connection point N0 of the battery 18 and the capacitor 22.

The switches SW1 to SW4, SWbatt, and SWcap are controlled to open and close by the control circuit 24. Further, a charging capacitor 19b is connected between the connection point N1 of the switches SW1 and SW2 and the connection point N3 of the switches SW3 and SW4. In this embodiment, a semiconductor switch is used as each switch, but a relay with mechanical contacts can also be used as the switch.

First, the external charging process in the present embodiment will be described with reference to FIGS. 5 to 9.
FIG. 5 is a processing flow of external charging processing, FIG. 6 is a processing flow of pre-charging information processing in external charging processing, and FIG. 7 is a processing flow of charging processing in external charging processing. FIG. 8 is a time chart showing the displacement of current and voltage during external charging, and FIG. 9 is a diagram showing the opening / closing position and current flow of the electric switch at each stage during external charging.

FIG. 8 shows the input voltage value Vin, the open / closed state of the switches SWbatt and SWcap, the open / closed state of the switches SW1 and SW3, and the open / closed state of the switches SW2 and SW4 in this order from the top. Following this, FIG. 8 shows the voltage Vcap between the terminals of the capacitor 22 (the voltage between the positive and negative terminals of the capacitor 22), the current Icap flowing through the capacitor 22, the voltage Vbatt between the terminals of the battery 18, and the battery 18. The current Ibatt, the voltage Vc between the terminals of the charging capacitor 19b, and the current Ic flowing through the charging capacitor 19b are shown.

As shown in FIG. 5 (external charging process), when the control circuit 24 detects that the external power supply 17 is connected to the power supply port 23, it detects pre-charging information processing (S10) and vehicle relay processing (S20) of the external charging process. ), The charging process (S30), and the charging completion process (S40) are sequentially executed. The external power supply 17 starts supplying electric power when a predetermined condition is satisfied after the connection to the vehicle 1.

As shown in FIG. 6 (pre-charging information processing S10), the control circuit 24 first calculates the input voltage value Vin (S11). The input voltage value Vin corresponds to the voltage of the vehicle 1 as seen from the external power source 17, and specifically, corresponds to the total voltage of the battery voltage and the capacitor voltage. Therefore, the control circuit 24 measures the input voltage value Vin (corresponding to the voltage of the first power line 5a) using the voltage sensor with the switches SWbatt and SWcap closed. Instead of directly measuring the input voltage value Vin, the battery voltage Vbatt and the capacitor voltage Vcap may be measured by voltage sensors, respectively, and these voltage values may be added to calculate the input voltage value Vin. ..

Next, the control circuit 24 determines whether or not the charging process is possible (S12). Specifically, it is determined whether or not the input voltage value Vin is equal to or higher than a predetermined voltage. The predetermined voltage is an external charging start threshold value, and is set to a voltage (for example, 55V) equal to or higher than the lower limit voltage (50V). When the input voltage value Vin is less than a predetermined voltage (S12; No), the process returns to step S11 after the capacitor charging process (S50) described later is executed. On the other hand, when the input voltage value Vin is equal to or higher than a predetermined voltage (S12; Yes), the control circuit 24 calculates the states of the battery 18 and the capacitor 22 (S13). That is, in this process, the control circuit 24 measures the battery voltage Vbatt, the capacitor voltage Vcap, the battery current Ibatt, and the capacitor current Icap using the voltage sensor and the current sensor, and acquires the SOCs of the battery 18 and the capacitor 22. ..

Next, the control circuit 24 determines the state of the battery 18 and the capacitor 22 (S14). In this process, the battery 18 and the capacitor 22 are in a healthy state where they can be charged normally (for example, the battery voltage Vbatt and the capacitor voltage Vcap are equal to or higher than the set threshold value, or each SOC is equal to or higher than the set threshold value. Is determined). When it is determined that the battery 18 or the capacitor 22 is not in a healthy state (S14; No), the failure diagnosis process is executed. On the other hand, when it is determined that both the battery 18 and the capacitor 22 are in a healthy state (S14; Yes), the process proceeds to the vehicle relay process (S20 in FIG. 5). In the vehicle relay process, the control circuit 24 switches the switches SWbatt, SWcap, SW1 to SW4 to the initial position (open position).

As shown in FIG. 7 (charging process S30), the control circuit 24 first calculates a charging command for the external power supply 17 (S31), and transmits the charging command to the external power supply 17 via a communication line (not shown) (S32). ). That is, the control circuit 24 calculates the charging current value to be supplied from the external power source 17 so that charging is completed in a predetermined charging schedule. The charging command is a signal requesting the supply of the charging current value obtained by this calculation. At this time, the control circuit 24 switches the switches SWbatt and SWcap to the closed position. On the other hand, also in the external power supply 17, the input voltage value Vin of the vehicle 1 is measured by using the voltage sensor provided in the external power supply 17. When the measured input voltage value Vin is equal to or higher than the lower limit voltage, the external power supply 17 supplies charging power when receiving a charging command from the vehicle 1 (see stage (1) in FIG. 9).

Referring to FIG. 8, at time t _1, switch SWbatt and SWcap is in ON (closed), (see stage 9 (1)) the charging by the external power source 17 is started. In this state, the battery 18 and the capacitor 22 are connected to the external power supply 17, but the charging circuit 19 is disconnected from the external power supply 17. As a result, the current supplied from the external power source 17 flows into the capacitor 22 and the battery 18 (current Icap, Ibatt> 0) to charge the capacitor 22 and the battery 18. Along with this, the capacitor voltage Vcap and the battery voltage Vbatt increase. Since the charge that can be stored in the capacitor 22 is less than the charge that can be stored in the battery 18, the capacitor voltage Vcap rises faster than the battery voltage Vbatt.

The control circuit 24 calculates the states of the battery 18 and the capacitor 22 in the same manner as in step S13 (S33). Then, the control circuit 24 determines the electrical energy of the capacitor 22 (S34). In this process, it is determined whether or not the electric energy of the capacitor 22 is within a predetermined range suitable for the amount of electric charge discharged to the battery 18. Specifically, it is determined whether or not the capacitor voltage Vcap is within a predetermined voltage range according to the charging schedule. When the electric energy of the capacitor 22 is not within the predetermined range (S34; No), the process returns to the process of step S31, and the charge command calculation is executed again. On the other hand, when the electric energy of the capacitor 22 is within a predetermined range (S34; Yes), an appropriate amount of discharge charge is accumulated in the capacitor 22, so that the control circuit 24 closes the switches SW1 and SW3. The switches SW2 and SW4 are opened (S35), the capacitor 22 is discharged, and the charging capacitor 19b is charged (see stage (2) in FIG. 9).

Referring to FIG. 8, at time t _2, the capacitor voltage Vcap is increased to a predetermined voltage value, (see stage 9 (2)) of the switch SW1 and SW3 are to ON. In this state, the current from the external power source 17 flows into the charging capacitor 19b, and the electric charge accumulated in the capacitor 22 is discharged (current Icap <0) and flows into the charging capacitor 19b (current Ic> 0). .. As a result, the voltage Vc between the terminals of the charging capacitor 19b (hereinafter referred to as “charging capacitor voltage Vc”) rises. On the other hand, the capacitor voltage Vcap decreases. As a result, the capacitor 22 becomes rechargeable. Note that the input voltage value Vin is the overall trend has increased with time, is maintained at or above the lower limit voltage of the external power source 17 is also at time t _3.

The switches SW1 and SW3 are maintained in the closed state until the charging capacitor voltage Vc rises to a predetermined voltage (S36; No). On the other hand, when the charging capacitor voltage Vc reaches a predetermined voltage (S36; Yes), the control circuit 24 opens the switches SW1 and SW3 and closes the switches SW2 and SW4 (S37), and the charging capacitor A charge is discharged from 19b to the battery 18 to charge the battery 18 (see stage (3) in FIG. 9).

Referring to FIG. 8, at time t _3, since the charging capacitor voltage Vc reaches a predetermined voltage, the switch SW1 and SW3 are OFF, the switch SW2 and SW4 are in ON (stage of FIG. 9 (3 )reference). In this state, the current from the external power source 17 flows into the capacitor 22 and the battery 18, and these are charged, and the electric charge accumulated in the charging capacitor 19b is also charged to the battery 18 through the switches SW2 and SWbatt. To. As a result, the capacitor voltage Vcap and the battery voltage Vbatt increase, and the inter-terminal voltage Vc of the charging capacitor 19b decreases.

The switch positions of the switches SW1 to SW4 are maintained until the battery voltage Vbatt rises and the charging capacitor voltage Vc drops to a predetermined voltage (S38; No). On the other hand, when the charging capacitor voltage Vc drops to a predetermined voltage (S38; Yes), the control circuit 24 determines whether or not the charging of the battery 18 is completed (S39). In this process, whether the battery voltage Vbatt has reached a predetermined charge end threshold value (for example, full charge voltage = 48 V), or whether the SOC of the battery 18 has reached a predetermined value (for example, 100%). Is judged.

If the charging of the battery 18 is not completed (S39; No), the process proceeds to step S33 again. That is, until the charging of the battery 18 is completed, the process of step S33~S39 are repeated (see time t ₂ ~t ₁₀ in FIG. 8), the vehicle driving apparatus 10 includes a stage of FIG. 9 (2) a stage (3 ) Alternately. On the other hand, when the charging of the battery 18 is completed (S39; Yes), the process proceeds to the charging completion process (S40 in FIG. 5). In the charge completion process, the control circuit 24 executes a process of switching the switches SW1 to SW4 to the open state, a process of transmitting a charge completion signal to the external power source 17, and the like, and ends the external charge process.

In FIG. 8, at time t _10, the charging of the battery 18 is completed (i.e., S39; Yes). As shown in FIG. 8, the input voltage value Vin is increased with as with the battery voltage Vbatt time, according to the charging schedule, the time t ₁₀ reaches the charge termination threshold (e.g., 120V). That is, both the battery voltage Vbatt and the capacitor voltage Vcap reach the rated voltage (48V, 72V).

Next, the capacitor charging process in the external charging process in the present embodiment will be described with reference to FIGS. 10 to 12.
FIG. 10 shows the processing flow of the capacitor charging process, FIG. 11 shows a time chart showing the displacement of current and voltage during the capacitor charging process, and FIG. 12 shows the opening / closing position and current flow of the electric switch at each stage during the capacitor charging process. It is a figure.

In pre-charging information processing (see FIG. 6), when the input voltage value Vin is less than a predetermined voltage (S12; No), the capacitor charging process S50 is executed. During the execution of the capacitor charging process, the charging power is not yet supplied from the external power source 17. In the capacitor charging process, the control circuit 24 calculates the state of the battery 18 and the capacitor 22 as in step S13 (S51). Next, the control circuit 24 opens the switches SW1 and SW3, closes the switches SW2 and SW4 (S52), and charges the charging capacitor 19b with the battery 18 (see stage (11) in FIG. 12).

Referring to FIG. 11, at time t _11, the switch SWbatt and SWcap are in ON (closed), that the input voltage value Vin is less than the external charging start threshold is detected. At time t _12, to start charging of the capacitor 22, the switches SW1, SW3 in the state of OFF (opened state), (see stage of FIG. 12 (11)) of the switch SW2, SW4 is to ON. In this state, the current (Ibatt <0) output from the battery 18 flows into the charging capacitor 19b (Ic> 0) through the switch SWbatt and the switch SW2. As a result, the charging capacitor voltage Vc rises. On the other hand, although the battery voltage Vbatt decreases, the amount of decrease is small because sufficient electric charge is accumulated in the battery 18.

The switches SW2 and SW4 are maintained in the closed state until the charging capacitor voltage Vc rises to a predetermined voltage (S53; No). On the other hand, when the charging capacitor voltage Vc reaches a predetermined voltage (S53; Yes), the control circuit 24 closes the switches SW1 and SW3 and opens the switches SW2 and SW4 (S54), and the charging capacitor A charge is discharged from 19b to the capacitor 22 to charge the capacitor 22 (see stage (12) in FIG. 12).

Referring to FIG. 11, at time t _13, the charging capacitor voltage Vc has risen to a predetermined voltage, the switch SW1, SW3 is ON, the switch SW2, SW4 is in OFF (stage of FIG. 12 (12 )reference). In this state, the current (current Ic <0) discharged from the charging capacitor 19b flows into the capacitor 22 (current Icap> 0). As a result, the charging capacitor voltage Vc decreases and the capacitor voltage Vcap increases (the battery voltage Vbatt does not change). As a result, the input voltage value Vin increases.

The switch positions of the switches SW1 to SW4 are maintained until the capacitor voltage Vcap rises and the charging capacitor voltage Vc drops to a predetermined voltage (S55; No). On the other hand, when the charging capacitor voltage Vc drops to a predetermined voltage (S55; Yes), the control circuit 24 determines whether or not the charging of the capacitor 22 is completed (S56). In this process, it is determined whether or not the capacitor voltage Vcap is sufficiently boosted, that is, whether or not the input voltage value Vin has reached the external charging start threshold value.

If the charging of the capacitor 22 is not completed (S56; No), the process proceeds to step S51 again. That is, until the charging of the capacitor 22 is completed, the process of step S51~S56 are repeated (see time t ₁₂ ~t ₁₈ in FIG. 11), the vehicle driving apparatus 10 includes a stage (12 stages in FIG. 12 (11) ) Alternately. On the other hand, when the charging of the capacitor 22 is completed (S56; Yes), the capacitor charging process is completed, and the process returns to the pre-charging information processing S10 (FIG. 6). After that, the external charging process (FIG. 5) is continued, and the charging process S30 (FIG. 7) is executed through the vehicle relay process S20. In the charging process S30, when the external power source 17 supplies the charging current, the vehicle driving device 10 is in the state of the stage (13) of FIG. 12 (same as the stage (1) of FIG. 9).

As described above, the capacitor charging process is executed under predetermined conditions in the external charging process. However, other than the external charging process, it is also executed when the capacitor 22 is discharged and the capacitor voltage drops while the vehicle 1 is traveling. That is, the capacitor charging process is also executed to maintain the capacitor voltage at a predetermined voltage or higher before supplying power to the auxiliary drive motor 20.

Next, the capacitor discharge process in the present embodiment will be described with reference to FIGS. 13 to 15. FIG. 13 shows the processing flow of the capacitor discharge process, FIG. 14 shows a time chart showing current and voltage displacement during the capacitor discharge process, and FIG. 15 shows the open / close position and current flow of the electric switch at each stage during the capacitor discharge process. It is a figure.

The capacitor discharge process is executed to discharge the electric charge accumulated in the capacitor 22 to the battery 18. This process discharges the capacitor 22 to a safe voltage when the capacitor 22 is replaced, and prevents the capacitor 22 from being charged more than necessary by the electric power regenerated by the auxiliary drive motor 20. Is executed to do.

When the capacitor discharge process is started, the control circuit 24 executes pre-discharge information processing (S61). In this process, the battery voltage Vbatt, the capacitor voltage Vcap, the battery current Ibatt, the capacitor current Icap, the SOCs of the battery 18 and the capacitor 22 and the like are acquired (see S13). Next, the control circuit 24 executes the vehicle relay process (S62). In this process, the switches SW1 to SW4 are set to the initial position (open position).

Next, the control circuit 24 executes the discharge process (S63 to S68). In the discharge process, the control circuit 24 calculates the states of the battery 18 and the capacitor 22 as in step S13 (S63). Next, the control circuit 24 closes the switches SW1 and SW3, opens the switches SW2 and SW4 (S64), releases an electric charge from the capacitor 22 to the charging capacitor 19b, and charges the charging capacitor 19b. (See stage (21) in FIG. 15).

Referring to FIG 14, at time t _21, the capacitor voltage Vcap is the predetermined voltage or more. At time t _22, the switch SW1, SW3 is ON, the switch SW2, SW4 is in OFF (open) (see stage of FIG. 15 (21)). In this state, the current (Icap <0) discharged from the capacitor 22 flows into the charging capacitor 19b through the switch SWcap and the switch SW1 (Ic> 0). As a result, the charging capacitor voltage Vc rises and the capacitor voltage Vcap falls.

The switches SW1 and SW3 are maintained in the closed state until the charging capacitor voltage Vc rises to a predetermined voltage (S65; No). On the other hand, when the charging capacitor voltage Vc reaches a predetermined voltage (S65; Yes), the control circuit 24 opens the switches SW1 and SW3 and closes the switches SW2 and SW4 (S66), and the charging capacitor A charge is discharged from 19b to the battery 18 to charge the battery 18 (see stage (22) in FIG. 15).

Referring to FIG 14, at time t _23, has risen charging capacitor voltage Vc to a predetermined voltage, the switch SW1, SW3 is OFF, the switch SW2, SW4 is ON (the stage of FIG. 15 (22 )reference). In this state, the current (current Ic <0) discharged from the charging capacitor 19b flows into the battery 18 (current Ibatt> 0). As a result, the charging capacitor voltage Vc decreases and the battery voltage Vbatt increases slightly (the capacitor voltage Vcap does not change).

The switch positions of the switches SW1 to SW4 are maintained until the battery voltage Vbatt rises and the charging capacitor voltage Vc drops to a predetermined voltage (S67; No). On the other hand, when the charging capacitor voltage Vc drops to a predetermined voltage (S67; Yes), the control circuit 24 determines whether or not the discharge of the capacitor 22 is completed (S68). In this process, it is determined whether or not the capacitor voltage Vcap has been sufficiently stepped down (that is, whether or not the capacitor voltage Vcap has reached the discharge end threshold value). In S68, it may be additionally determined whether or not the input voltage value Vin has reached the discharge end threshold value set for the input voltage value Vin.

If the discharge of the capacitor 22 is not completed (S68; No), the process proceeds to step S61 again. That is, the processes of steps S61 to S68 are repeated until the discharge of the capacitor 22 is completed (see times t _{22 to} t _{28 in} FIG. 14), and the vehicle drive device 10 has the stage (21) and the stage (22) in FIG. ) Alternately. On the other hand, when the discharge of the capacitor 22 is completed (S68; Yes), the capacitor discharge process is completed and the process proceeds to the discharge completion process (S69). In the discharge completion process, the switches SW1 to SW4 are opened, and the capacitor discharge process is completed. Incidentally, the stage of FIG. 15 (23), in the maintenance of the vehicle 1 such as, switches SWbatt and SWcap indicates the standby state of being turned OFF at time t _29.

The operation of the vehicle drive device 10 according to the embodiment of the present invention will be described below.
According to the present embodiment, the vehicle drive device 10 mounted on the vehicle 1 is provided with a power supply 3 in which a rechargeable battery 18 and a power supply capacitor 22 are connected in series, and a main drive in which the voltage of the battery 18 is provided. The motor 16 (first vehicle drive motor), the auxiliary drive motor 20 (second vehicle drive motor) provided with the total voltage (Vin) of the battery 18 and the power supply capacitor 22, and the charging connected to the power supply 3. A circuit 19 and a control circuit 24 for controlling charging / discharging of the power supply 3 via the charging circuit 19 are provided. The power supply capacitor 22 has a first terminal and a second terminal, and the charging circuit 19 has a first terminal and a second terminal. Switch SW1 (first) for electrically connecting and disconnecting the charging capacitor 19b having the first terminal and the second terminal, the first terminal of the charging capacitor 19b, and the first terminal of the power supply capacitor 22. 1 switch), switch SW2 (second switch) for electrically connecting and disconnecting the first terminal of the charging capacitor 19b and the second terminal of the power supply capacitor 22, and charging capacitor 19b. The switch SW3 (third switch) for electrically connecting and disconnecting the second terminal and the positive terminal of the battery 18, and the second terminal of the charging capacitor 19b and the negative terminal of the battery 18 are electrically connected. The control circuit 24 is configured to operate the switches SW1 to SW4 to control the charging and discharging of the battery 18 and the power supply capacitor 22 by providing a switch SW4 (fourth switch) for disconnecting and disconnecting. There is.

In the present embodiment configured as described above, the power supply 3 includes the battery 18 and the capacitor 22 connected in series, and the first power line 5a connected to the capacitor 22 and the second power line connected to the battery 18. It has at least 5b. The first power line 5a and the second power line 5b can provide different power supply voltages. The sub-drive motor 20 is driven by the first power line 5a, and the main drive motor 16 is driven by the second power line 5b. As described above, in the present embodiment, a plurality of power supply voltages can be supplied with a simple and simple configuration. Further, in the present embodiment, since the power supply 3 is configured by connecting the battery 18 and the power supply capacitor 22 in series, the charging circuit has a simple configuration consisting of four electric switches and a charging capacitor as a charge buffer. be able to. The control circuit 24 can easily charge and discharge electric charges between the battery 18 and the power supply capacitor 22 by opening and closing these four electric switches.

Further, preferably, in the present embodiment, the rated voltage (72V) of the power supply capacitor 22 is larger than the rated voltage (48V) of the battery 18. In the present embodiment configured as described above, when the power supply 3 is charged by the external power supply 17, even if the rated voltage of the battery 18 is smaller than the lower limit voltage of the external power supply 17, the rated voltage is larger than that of the battery 18. By connecting 22 in series, the input voltage value Vin of the vehicle 1 can be easily maintained to be larger than the lower limit voltage.

Further, in the present embodiment, specifically, the positive terminal of the battery 18 and the second terminal of the power supply capacitor 22 are connected, and the power supply 3 is connected in parallel to the series circuit of the switches SW1 to SW4 for charging. The capacitor 19b is connected in parallel to the series circuit of the switch SW2 and the switch SW3, and the connection point N2 between the switch SW2 and the switch SW3 is connected to the positive terminal of the battery 18.

Further, preferably, in the present embodiment, the control circuit 24 closes the switches SW1 and SW3 and opens the switches SW2 and SW4 (S35), and a part of the electric charge stored in the power supply capacitor 22. In the first stage (stage (2) in FIG. 9) in which the electric charge capacitor 19b is stored, the switches SW1 and SW3 are opened and the switches SW2 and SW4 are closed (S37), and the electric charge is stored in the charging capacitor 19b. The charging circuit 19 is controlled so as to repeat the second stage (stage (3) of FIG. 9) of charging the battery 18 with the charged electric charge a plurality of times.

In the present embodiment configured as described above, the battery 18 can be charged by discharging the electric charge of the power supply capacitor 22 to the battery 18 via the charging circuit 19. At this time, for example, by supplying charging power from the external power source 17 to the power supply capacitor 22, the battery 18 and the power supply capacitor 22 can be substantially charged at the same time by the external power source 17.

Further, preferably in the present embodiment, the control circuit 24 opens the switches SW1 and SW3 and closes the switches SW2 and SW4 (S52) to charge a part of the electric charge stored in the battery 18. The third stage (stage (11) in FIG. 12) of storing in the charging capacitor 19b, the switches SW1 and SW3 are closed and the switches SW2 and SW4 are opened (S54), and the switches SW1 and SW4 are stored in the charging capacitor 19b. The charging circuit 19 is controlled so as to repeat the fourth stage (stage (12) in FIG. 12) of charging the power supply capacitor 22 by electric charge a plurality of times.

In the present embodiment configured as described above, the power supply capacitor 22 can be charged by discharging the electric charge of the battery 18 to the power supply capacitor 22 via the charging circuit 19.

Further, preferably in the present embodiment, the power supply capacitor 22 is configured so that the charge that can be stored is smaller than the charge that can be stored in the battery 18. In the present embodiment configured as described above, when the power supply capacitor 22 is charged by the battery 18, the total voltage of the battery 18 and the power supply capacitor 22 can be increased. Therefore, when the total voltage is lower than the lower limit voltage of the external power supply 17, the total voltage can be boosted to enable external charging.

1 Vehicle 3 Power supply 10 Vehicle drive device 16 Main drive motor (first vehicle drive motor)
17 External power supply 18 Battery 18a Battery cell 19 Charging circuit 19b Charging capacitor 20 Sub-drive motor (second vehicle drive motor)
22 Capacitor (power supply capacitor)
24 Control circuit 28 Electric load G Body ground N0, N1, N2, N3 Connection point SWbatt, SWcap switch SW1 to SW4 switch (1st to 4th switches)

Claims (6)

It is a vehicle drive device mounted on a vehicle.
A power supply in which a rechargeable battery and a power supply capacitor are connected in series,
A first vehicle drive motor to which the voltage of the battery is provided, and
A second vehicle drive motor that provides the total voltage of the battery and the power supply capacitor,
The charging circuit connected to the power supply and
A control circuit that controls charging / discharging of the power supply via the charging circuit is provided.
The power supply capacitor has a first terminal and a second terminal.
The charging circuit electrically connects and disconnects a charging capacitor having a first terminal and a second terminal, and the first terminal of the charging capacitor and the first terminal of the power supply capacitor. A first switch, a second switch for electrically connecting and disconnecting the first terminal of the charging capacitor and the second terminal of the power supply capacitor, and a second terminal of the charging capacitor. And a third switch for electrically connecting and disconnecting the positive terminal of the battery, and a fourth switch for electrically connecting and disconnecting the second terminal of the charging capacitor and the negative terminal of the battery. With a switch,
The vehicle driving device is configured such that the control circuit operates the first, second, third, and fourth switches to control the charging and discharging of the battery and the power supply capacitor. The vehicle drive device according to claim 1, wherein the rated voltage of the power supply capacitor is larger than the rated voltage of the battery. The positive electrode terminal of the battery and the second terminal of the power supply capacitor are connected to each other.
The power supply is connected in parallel to the series circuit of the first, second, third and fourth switches.
The charging capacitor is connected in parallel to the series circuit of the second switch and the third switch.
The vehicle drive device according to claim 1 or 2, wherein the connection point between the second switch and the third switch is connected to the positive electrode terminal of the battery. The control circuit
The first, in which the first and third switches are closed and the second and fourth switches are opened, and a part of the electric charge stored in the power supply capacitor is stored in the charging capacitor. Stages and
A second step of charging the battery with the electric charge stored in the charging capacitor by opening the first and third switches and closing the second and fourth switches.
The vehicle driving device according to claim 3, wherein the charging circuit is controlled so as to repeat the process a plurality of times. The control circuit
With the third step of opening the first and third switches and closing the second and fourth switches and storing a part of the electric charge stored in the battery in the charging capacitor. ,
A fourth step in which the first and third switches are closed and the second and fourth switches are opened to charge the power supply capacitor with the electric charge stored in the charging capacitor.
The vehicle driving device according to claim 3 or 4, wherein the charging circuit is controlled so as to repeat the process a plurality of times. The vehicle driving device according to any one of claims 1 to 5, wherein the power supply capacitor has a charge that can be stored less than the charge that can be stored in the battery.

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