JP7115366B2 - power system - Google Patents

Description

The present disclosure relates to a power supply system including a first power storage device and a second power storage device having a voltage lower than that of the first power storage device.

Conventionally, as an electric system of an electric vehicle, a first power storage device, a smoothing capacitor that smoothes the DC voltage of the first power storage device, an inverter that converts the DC voltage of the smoothing capacitor into an AC voltage and supplies it to a driving motor, a system main relay provided between the first power storage device and the smoothing capacitor; a second power storage device having a voltage lower than that of the first power storage device; or a bidirectional DC/DC converter that steps down the voltage of the smoothing capacitor and supplies it to the second power storage device, boosts the voltage of the second power storage device and supplies it to the smoothing capacitor, and a control device that controls the entire system. is known (see, for example, Patent Literature 1). When the control device of this electric system receives an activation instruction by turning on the ignition switch, it controls the bidirectional DC/DC converter to perform a step-up operation, and when the voltage of the smoothing capacitor reaches a precharge completion threshold, both Stops the step-up operation of the forward DC/DC converter and closes the system main relay.

JP 2007-318849 A

In the electric system as described above, if the voltage of the smoothing capacitor exceeds the withstand voltage due to an abnormality of the bidirectional DC/DC converter while the smoothing capacitor is being precharged by the bidirectional DC/DC converter, Failure may occur not only in the smoothing capacitor but also in various auxiliary devices connected to it.

Therefore, the present disclosure provides a method for controlling the voltage of a capacitor connected to a voltage conversion device that boosts power from a second power storage device having a voltage lower than that of a first power storage device when an abnormality occurs in the precharge of the capacitor. The main purpose is to suppress the occurrence of equipment failures.

A power supply system of the present disclosure includes a first power storage device and a second power storage device having a voltage lower than that of the first power storage device. a power line and a negative power line; an upper arm element connected to the positive power line and the high voltage power line; and a lower arm element connected to the positive power line and the negative power line. 1 voltage conversion device, a first capacitor connected to the positive power line and the negative power line between the relay and the first voltage conversion device, the high voltage power line and the negative power line and a second capacitor connected to the positive electrode side power line and the negative electrode side power line between the relay and the first capacitor, and from the first power storage device and the first voltage conversion device side A second voltage capable of stepping down electric power and supplying it to the second power storage device, and stepping up power from the second power storage device and supplying it to the first power storage device and the first voltage conversion device. While the first and second capacitors are precharged by the power from the conversion device and the second power storage device boosted by the second voltage conversion device in a state where the relay is opened, the first When the voltage difference between the power storage device and the first capacitor is out of the predetermined range and the voltage of the first capacitor is equal to or higher than the predetermined voltage, the upper arm element and the lower arm element of the first voltage conversion device and a control device for turning on and stopping the second voltage conversion device.

In the power supply system of the present disclosure, while the first and second capacitors are precharged by the power from the second power storage device boosted by the second voltage conversion device with the relay open, the first power storage device and the first capacitor, and the voltage on the first capacitor are monitored. Then, when the voltage difference between the first power storage device and the first capacitor is outside the predetermined range and the voltage of the first capacitor is equal to or higher than the predetermined voltage, the upper arm element and the lower arm element of the first voltage conversion device The second voltage converter is deactivated while being turned on. As a result, an abnormality in the precharging of the first and second capacitors by the second voltage conversion device is detected without using a dedicated abnormality detection circuit or the like, and the upper arm of the first voltage conversion device is detected when the abnormality is detected. Both the first and second capacitors can be discharged by turning on the device and the lower arm device. As a result, when an abnormality occurs in the precharging of the first and second capacitors using the second voltage converter, the occurrence of failures in the first and second capacitors and devices connected to them can be suppressed satisfactorily. becomes possible.

1 is a schematic configuration diagram showing a vehicle including a power supply system of the present disclosure; FIG. 4 is a flow chart showing an example of a routine executed by the control device of the power supply system of the present disclosure;

Next, a mode for carrying out the invention of the present disclosure will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a hybrid vehicle V as a vehicle including a power supply system 1 of the present disclosure. The hybrid vehicle V shown in the figure includes, in addition to the power supply system 1, an engine EG, a single pinion planetary gear PG, motor generators MG1 and MG2 that exchange electric power with the power supply system 1, and a hybrid electronic control unit that controls the entire vehicle. (hereinafter referred to as "HVECU") 10 and the like. The power supply system 1 also includes a high-voltage battery (first power storage device) 2, a positive side system main relay SMRB and a negative side system main relay SMRG that are closed when an excitation current is supplied to coils (not shown). A power control unit (hereinafter referred to as "PCU") 3, which is connected to a high voltage battery 2 via system main relays SMRB and SMRG on the side and negative side and drives motor generators MG1 and MG2, has a voltage lower than that of the high voltage battery 2. It includes a low-voltage battery (second power storage device) 4, a bidirectional DC/DC converter (second voltage conversion device) 5, and the like.

The engine EG is an internal combustion engine that generates power by explosive combustion of a mixture of air and a hydrocarbon fuel such as gasoline, light oil, or LPG, and is controlled by an engine electronic control unit (not shown). The planetary gear PG rotatably supports a sun gear connected to the motor generator MG1 (rotor), a ring gear connected to the output shaft and connected to the motor generator MG2 (rotor), and a plurality of pinion gears. a planetary carrier coupled to the crankshaft. The output shaft is connected to left and right driving wheels DW via a differential gear DF and a drive shaft DS.

Motor generators MG1 and MG2 are both synchronous generator motors (three-phase AC motors). Motor generator MG1 mainly operates as a power generator that is driven by engine EG operated under load to generate electric power. Motor generator MG2 is mainly driven by at least one of the electric power from high-voltage battery 2 and the electric power from motor generator MG1 to operate as an electric motor that generates driving torque, and when hybrid vehicle V is braked, Outputs regenerative braking torque. Further, motor generators MG1 and MG2 can exchange power with high-voltage battery 2 via PCU3, and can exchange power with each other via PCU3.

The HVECU 10 is a microcomputer including a CPU, ROM, RAM, etc. (not shown). The HVECU 10 is connected to an electronic engine control unit and the like via communication lines such as CAN, and is also connected to various sensors such as a start switch SS, an accelerator pedal position sensor, a shift position sensor, and a vehicle speed sensor. When the hybrid vehicle V travels, the HVECU 10 sets the required torque required for traveling based on the accelerator opening and the vehicle speed, as well as the required power and target rotation speed for the engine EG, and torque command values for the motor generators MG1 and MG2. etc.

In addition, HVECU 10 controls opening and closing of positive side system main relay SMRB and negative side system main relay SMRG. That is, when the driver turns on the start switch SS to request system start-up of the hybrid vehicle V, the HVECU 10 supplies an exciting current to coils (not shown) of the positive side system main relay SMRB and the negative side system main relay SMRG. Both are closed (turned on) to electrically connect the high-voltage battery 2 and the PCU 3 . Further, when the driver turns off the start switch SS to request system stop of the hybrid vehicle V, the HVECU 10 cuts off the supply of the excitation current to the positive side system main relay SMRB and the negative side system main relay SMRG. Both are opened (turned off) to disconnect the electrical connection between the high-voltage battery 2 and the PCU 3 .

A high-voltage battery 2 that constitutes the power supply system 1 is, for example, a lithium-ion secondary battery or a nickel-hydrogen secondary battery having a rated output voltage of 200 to 400V. A positive terminal of the high voltage battery 2 is connected to a positive power line PL via a positive system main relay SMRB, and a negative terminal of the high voltage battery 2 is connected to negative power via a negative system main relay SMRG. line NL is connected. Further, the high voltage battery 2 is provided with a voltage sensor 21 for detecting the voltage VB across the terminals of the high voltage battery 2 and a current sensor 22 for detecting the current (charging/discharging current) IB flowing through the high voltage battery 2. ing. The voltage VB across the terminals of the high voltage battery 2 detected by the voltage sensor 21 and the current IB detected by the current sensor 22 are directly transmitted through a signal line (not shown) or sent to a power management electronic (not shown) that manages the high voltage battery 2. It is transmitted to the HVECU 10 by the control device.

The PCU 3 that constitutes the power supply system 1 includes a first inverter 31 that drives the motor generator MG1, a second inverter 32 that drives the motor generator MG2, and boosts electric power from the high-voltage battery 2, and also boosts electric power from the motor generators MG1 and MG2. A step-up/step-down converter (first voltage conversion device) 33 that can step down the voltage from the power supply, and a motor electronic control unit (hereinafter referred to as “MGECU”) that controls the first and second inverters 31 and 32 and the step-up/step-down converter 33. ) 30.

The first and second inverters 31 and 32 are composed of six transistors (for example, insulated gate bipolar transistors (IGBT)) (not shown) and six diodes (not shown) connected in parallel to each transistor in the reverse direction. It is. The six transistors are paired two by two so as to be on the source side and the sink side with respect to the high voltage power line HPL and the negative power line NL. Each of the three-phase coils (U-phase, V-phase, W-phase) of motor generators MG1 and MG2 is electrically connected to each of the connection points between the paired transistors.

The buck-boost converter 33 includes two transistors (for example, insulated gate bipolar transistors) Tra and Trb, two diodes Da and Db connected in parallel in opposite directions to the transistors Tra and Trb, and a reactor L. . One end of the reactor L is electrically connected to the positive power line PL, and the other end of the reactor L is connected to the emitter of one transistor (upper arm element) Tra and the collector of the other transistor (lower arm element) Trb. are electrically connected. The collector of the one transistor Tra is electrically connected to the high voltage power line HPL, and the emitter of the other transistor Trb is electrically connected to the negative power line NL.

PCU 3 further includes a filter capacitor (first capacitor) 34 , a smoothing capacitor (second capacitor) 35 , and voltage sensors 36 and 37 . The positive terminal of filter capacitor 34 is electrically connected to positive power line PL (one end of reactor L) between positive system main relay SMRB and buck-boost converter 33, and the negative terminal of filter capacitor 34 is connected to the negative pole. Side system main relay SMRG and step-up/down converter 33 are electrically connected to negative power line NL. As a result, the voltage on the high voltage battery 2 side of the buck-boost converter 33 (the voltage applied to the buck-boost converter 33 ) is smoothed by the filter capacitor 34 . Also, the voltage sensor 36 detects the voltage across the terminals of the filter capacitor 34 (voltage before boosting) VL.

The positive terminal of the smoothing capacitor 35 is electrically connected to the high-voltage power line HPL (collector of the transistor Tra of the buck-boost converter 33) between the buck-boost converter 33 and the first and second inverters 31, 32, and smoothed. A negative terminal of the capacitor 35 is electrically connected to the negative power line NL and the emitter of the transistor Trb of the buck-boost converter 33 between the buck-boost converter 33 and the first and second inverters 31 and 32 . As a result, the voltage boosted by the buck-boost converter 33 is smoothed by the smoothing capacitor 35 . Further, the voltage sensor 37 detects a terminal voltage (voltage after boosting) VH of the smoothing capacitor 35 . The voltage VL between the terminals of the filter capacitor 34 detected by the voltage sensor 36 and the voltage VH between the terminals of the smoothing capacitor 35 detected by the voltage sensor 37 are transmitted to the MGECU 30 and directly via a signal line (not shown) or It is transmitted to the HVECU 10 by the MGECU 30 .

The MGECU 30 is a microcomputer including a CPU, ROM, RAM and the like (not shown), and is connected to the HVECU 10 and the like via communication lines such as CAN. The MGECU 30 also receives a command signal from the HVECU 10, a detected value of a resolver (not shown) that detects the rotational position of the rotor of the motor generator MG1, a detected value of a resolver that detects the rotational position of the rotor of the motor generator MG2, and a buck-boost converter 33. A current value from a current sensor (not shown), terminal voltages VL and VH from voltage sensors 36 and 37, and phase currents applied to motor generators MG1 and MG2 detected by current sensors (not shown) are inputted. Based on these input signals, the MGECU 30 generates gate signals (switching control signals) to the first and second inverters 31 and 32 and the step-up/step-down converter 33, and controls switching of these.

A low-voltage battery 4 that constitutes the power supply system 1 is, for example, a lead-acid battery having a rated output voltage of 12 V, and is connected to a plurality of auxiliary machines (low-voltage auxiliary machines) via low-voltage power lines. Bidirectional DC/DC converter (DDC) 5 is connected to positive power line PL between positive system main relay SMRB and PCU3, and is connected to negative power between negative system main relay SMRG and PCU3. connected to line NL. Bidirectional DC/DC converter 5 is also connected to low-voltage battery 4 and a plurality of auxiliary devices via the low-voltage power line. In addition to the bi-directional DC/DC converter 5, the positive power line PL and the negative power line NL are connected to high-voltage auxiliary equipment such as an air conditioner compressor (inverter compressor) and a converter to AC 100V. be done.

Bidirectional DC/DC converter 5 steps down the power on the positive power line PL side, that is, on the high voltage battery 2 and PCU 3 (buck-boost converter 33) sides to In addition to supplying power to the voltage battery 4, the power from the low voltage battery 4 can be boosted and supplied to the positive power line PL side, that is, the high voltage battery 2 and PCU 3 side. In the present embodiment, the bidirectional DC/DC converter 5 includes a voltage conversion circuit 50, a voltage sensor 51 that detects the output voltage of the voltage conversion circuit 50 toward the high voltage battery 2 and the PCU 3, and a low An electronic control unit (hereinafter referred to as "DDC ECU") that feedback-controls the voltage conversion circuit 50 so that the detected value of a voltage sensor (not shown) that detects the output voltage to the voltage battery 4, the voltage sensor 51, etc. becomes the target voltage Vtag. 55, etc. Further, in the present embodiment, the target voltage Vtag of the bidirectional DC/DC converter 5 (voltage conversion circuit 50) is set by the HVECU 10 and transmitted from the HVECU 10 to the DDC ECU 55 via the communication line.

Next, referring to FIG. 2, the control procedure of the power supply system 1 when the driver turns on the start switch SS and the hybrid vehicle V is system-started will be described. FIG. 2 is a flow chart showing an example of a routine executed by the HVECU 10 when the start switch SS is turned on and system startup of the hybrid vehicle V is requested. In the following description, the transistor Tra of the step-up/step-down converter 33 is called "upper arm element Tra", and the transistor Trb is called "lower arm element Trb".

When the driver turns on the start switch SS, the HVECU 10 (CPU) acquires the terminal voltage VB of the high-voltage battery 2 detected by the voltage sensor 21 as shown in FIG. Then, the inter-terminal voltage VB is set as the target voltage Vtag for precharging the smoothing capacitor 35, and the set target voltage Vtag is transmitted to the DDC ECU 55 of the bidirectional DC/DC converter 5 (step S100). Upon receiving the target voltage Vtag from the HVECU 10, the DDC ECU 55 adjusts the voltage conversion circuit 50 so that the detection value of the voltage sensor 51 becomes the target voltage Vtag in a state in which the positive and negative side system main relays SMRB and SMRG are opened. Feedback control is started, and when the detected value of the voltage sensor 51 reaches the target voltage Vtag, the voltage conversion circuit 50 is feedback-controlled so that the detected value is maintained at the target voltage Vtag.

After the process of step S100, the HVECU 10 acquires the terminal voltage VB of the high voltage battery 2 detected by the voltage sensor 21 and the terminal voltage VL of the filter capacitor 34 detected by the voltage sensor 36, and Whether the absolute value |VB−VL| of the difference between the voltage VB and the voltage VL across the terminals is greater than a predetermined relatively small value α (positive value, for example, about 30 V) (from −α to +α (predetermined range)) is determined (step S110). is greater than the value α (step S110: YES), the HVECU 10 transmits the target voltage Vtag to the DDC ECU 55 in step S100 and It is determined whether or not the time tref has elapsed (step S120). The time tref as the threshold value used in step S120 is the time when the voltage VL between the terminals of the filter capacitor 34 and the voltage VH between the terminals of the smoothing capacitor 35 become equal to the voltage VL between the terminals of the filter capacitor 34 and the voltage VH between the terminals of the smoothing capacitor 35 after the target voltage Vtag is transmitted to the DDC ECU 55. It is defined as the time during which it can be considered that the target voltage Vtag has been reached by precharging.

If it is determined in step S120 that the time tref has not elapsed after the transmission of the target voltage Vtag to the DDC ECU 55, the HVECU 10 executes the determination process in step S110 again, and in step S110 the absolute value |VB-VL| When it is determined that the value is equal to or less than the value α (within the range from -α to +α) (step S110: NO), the HVECU 10 closes the positive side system main relay SMRB and the negative side system main relay SMRG (step S180). . At this time, since the voltage VL across the terminals of the filter capacitor 34 and the voltage VH across the terminals of the smoothing capacitor 35 are close to the target voltage Vtag, that is, the voltage VB across the terminals of the high-voltage battery 2, When system main relays SMRB and SMRG are closed, it is possible to suppress a large inrush current from flowing through positive power line PL and PCU 3 . After the processing of step S180, the HVECU 10 shifts the vehicle state to the READY-ON state in which the hybrid vehicle V is allowed to run (step S190), and terminates the routine of FIG.

On the other hand, when it is determined in step S110 that the absolute value |VB-VL| S120: YES), the HVECU 10 acquires the terminal voltage VL of the filter capacitor 34 detected by the voltage sensor 36, and determines whether or not the terminal voltage VL is equal to or higher than a predetermined overvoltage threshold Vref (step S130). The overvoltage threshold Vref used in step S130 is set to a value higher than the rated voltage of the high voltage battery 2 and lower than the withstand voltages of the filter capacitor 34, the smoothing capacitor 35 and the high voltage auxiliaries.

If it is determined in step S130 that the voltage VL between the terminals of the filter capacitor 34 is equal to or higher than the overvoltage threshold Vref (step S130: YES), the voltage conversion circuit 50 of the bidirectional DC/DC converter 5, the voltage sensor 51, the DDC ECU 55, or the like , the filter capacitor 34 is overcharged beyond the target voltage Vtag. Therefore, when it is determined in step S130 that the inter-terminal voltage VL is equal to or higher than the overvoltage threshold Vref (step S130: YES), the HVECU 10 turns on both the upper arm element Tra and the lower arm element Trb of the step-up/step-down converter 33. A command signal (ON command) is transmitted to the MGECU 30 so as to turn on (step S140).

Upon receiving the command signal from HVECU 10, MGECU 30 turns on both upper arm element Tra and lower arm element Trb of buck-boost converter 33 until inter-terminal voltage VL detected by voltage sensor 36 becomes equal to or less than a predetermined value. As a result, the charges accumulated in the filter capacitor 34 and the smoothing capacitor 35 can flow (releasing) to the negative power line NL to discharge the filter capacitor 34 and the smoothing capacitor 35 quickly. During discharge of the filter capacitor 34 and the smoothing capacitor 35, the MGECU 30 monitors the temperature of the upper arm element Tra and the lower arm element Trb, and controls the temperature of the upper arm element Tra so that the temperature of the upper arm element Tra does not exceed the allowable temperature. Tra and the like are turned off as appropriate.

After transmitting the command signal to MGECU 30 in step S140, HVECU 10 transmits a command signal to DDC ECU 55 to stop the operation of bidirectional DC/DC converter 5 (step S150). The HVECU 10 also turns on a warning light provided on an instrument panel or the like (not shown) to indicate that an abnormality has occurred in precharging by the bidirectional DC/DC converter 5 (step S160). Furthermore, the HVECU 10 prohibits the operation of the bidirectional DC/DC converter 5 and the transition to the READY-ON state (step S170), and terminates the routine of FIG. On the other hand, when it is determined in step S130 that the voltage VL between the terminals of the filter capacitor 34 is less than the overvoltage threshold Vref (step S130: NO), the HVECU 10 detects that the bidirectional DC/DC converter 5 is connected to the low voltage battery 4 due to some abnormality. 2, the process of step S140 is skipped, the process of steps S150 to S170 is executed, and the routine of FIG. 2 is terminated.

As a result of executing the routine of FIG. 2 as described above, in the hybrid vehicle V equipped with the power supply system 1, the filter capacitor 34 and the smoothing capacitor 35 by the bidirectional DC/DC converter 5 are detected without using a dedicated abnormality detection circuit or the like. When the abnormality is detected, both the upper arm element Tra and the lower arm element Trb of the buck-boost converter 33 are turned on to discharge both the filter capacitor 34 and the smoothing capacitor 35. be able to. As a result, when an abnormality occurs in the precharging of the filter capacitor 34 and the smoothing capacitor 35 using the bidirectional DC/DC converter 5, the failure of the filter capacitor 34, the smoothing capacitor 35, and the high-voltage auxiliaries connected to them It is possible to satisfactorily suppress the occurrence of

In addition, by turning on the upper arm element Tra and the lower arm element Trb of the buck-boost converter 33 (step S140) prior to transmitting the operation stop command to the bidirectional DC/DC converter 5 (step S150), the bidirectional It is possible to satisfactorily prevent the terminal voltage VL of the filter capacitor 34 and the terminal voltage VH of the smoothing capacitor 35 from exceeding the withstand voltage before the operation of the DC/DC converter 5 stops. Furthermore, by discharging the smoothing capacitor 35 at the same time as the filter capacitor 34, there is no need to discharge the smoothing capacitor 35 again when the driver turns off the start switch SS after the process of step S170.

As described above, the power supply system 1 of the present disclosure includes a high voltage battery 2, a low voltage battery 4 having a voltage lower than that of the high voltage battery 2, and positive side system main relay SMRB or negative side system main relay SMRG. A positive power line PL and a negative power line NL connected to the high voltage battery 2 via, an upper arm element Tra connected to the positive power line PL and the high voltage power line HPL, and a positive power line PL and a lower arm element Trb connected to the negative power line NL; Filter capacitor 34 connected to side power line NL, smoothing capacitor 35 connected to high voltage power line HPL and negative side power line NL, positive side and negative side system main relays SMRB, SMRG, and filter capacitor 34 are connected to the positive power line PL and the negative power line NL between the high voltage battery 2 and the step-up/down converter 33 side, step down the power from the high voltage battery 2 and the step-up/down converter 33 side, and supply the low voltage battery 4 side with It includes a bi-directional DC/DC converter 5 capable of stepping up electric power and supplying it to the high voltage battery 2 and step-up/step-down converter 33 side, and an HVECU 10 as a control device.

In HVECU 10, filter capacitor 34 and smoothing capacitor 35 are precharged with power from low-voltage battery 4 boosted by bidirectional DC/DC converter 5 while positive and negative system main relays SMRB and SMRG are open. During this period, the voltage difference |VB-VL| between the high-voltage battery 2 and the filter capacitor 34 and the voltage VL across the terminals of the filter capacitor 34 are monitored (steps S110, S130). When the voltage difference |VB-VL| is outside the predetermined range (range from -α to +α) and the terminal voltage VL is equal to or greater than the overvoltage threshold (predetermined voltage) Vref (steps S110, S120, S130: YES), cooperates with MGECU 30 to turn on upper arm element Tra and lower arm element Trb of buck-boost converter 33 (step S140), and stop bidirectional DC/DC converter 5 (step S150). . As a result, in the power supply system 1, when an abnormality occurs in the precharging of the filter capacitor 34 and the smoothing capacitor 35 using the bidirectional DC/DC converter 5, the filter capacitor 34, the smoothing capacitor 35, and the high power supply connected to them It is possible to satisfactorily suppress the occurrence of failure of the voltage auxiliary machine.

In step S130 of FIG. 2, instead of the voltage VL across the filter capacitor 34, the voltage VH across the smoothing capacitor 35 may be compared with the overvoltage threshold Vref. Further, the vehicle including the power supply system 1 described above is not limited to the two-motor type (series-parallel type) hybrid vehicle V having the planetary gear PG for power distribution. That is, the vehicle to which the invention of the present disclosure is applied may be a one-motor hybrid vehicle, a series hybrid vehicle, a parallel hybrid vehicle, or a plug-in hybrid vehicle. It may be a hybrid vehicle or an electric vehicle. Furthermore, PCU 3 may include two or more buck-boost converters.

It goes without saying that the invention of the present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment of the invention is merely a specific embodiment of the invention described in the column of Means for Solving the Problems, and is described in the column of Means for Solving the Problems. It is not intended to limit the inventive elements.

INDUSTRIAL APPLICABILITY The invention of the present disclosure can be used in the power supply system manufacturing industry and the like.

1 power supply system, 2 high voltage battery, 3 power control unit (PCU), 4 low voltage battery, 5 bidirectional DC/DC converter, 50 voltage conversion circuit, 55 electronic control unit (DDCECU), 10 hybrid electronic control unit (HVECU) ), 21, 36, 37, 51 voltage sensor, 22 current sensor, 30 motor electronic control unit (MGECU), 31 first inverter, 32 second inverter, 33 buck-boost converter, 34 filter capacitor, 35 smoothing capacitor Da, Db diode, DF differential gear, DS drive shaft, DW drive wheel, EG engine, HPL high voltage power line, L reactor, MG1, MG2 motor generator, NL negative power line, PG planetary gear, PL positive power line, SMRB positive side system main relay, SMRG negative side system main relay, Tra, Trb transistor, V hybrid vehicle.

Claims (1)

In a power supply system including a first power storage device and a second power storage device having a voltage lower than that of the first power storage device,
a positive power line and a negative power line connected to the first power storage device via relays;
a first voltage converter including an upper arm element connected to the positive power line and the high voltage power line, and a lower arm element connected to the positive power line and the negative power line;
a first capacitor connected to the positive power line and the negative power line between the relay and the first voltage converter;
a second capacitor connected to the high voltage power line and the negative power line;
It is connected to the positive power line and the negative power line between the relay and the first capacitor, and steps down the power from the first power storage device and the first voltage conversion device to reduce the voltage of the second power storage device. a second voltage conversion device capable of supplying power to a device and boosting power from the second power storage device and supplying the power to the first power storage device and the first voltage conversion device;
While the first and second capacitors are precharged by the power from the second power storage device boosted by the second voltage conversion device with the relay opened, When the voltage difference with the first capacitor is out of the predetermined range and the voltage of the first capacitor is equal to or higher than the predetermined voltage, the upper arm element and the lower arm element of the first voltage conversion device are turned on. , and a control device for stopping the second voltage conversion device.

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