JP2020145867A - Power supply system - Google Patents

Abstract

To complete precharge while suppressing the overvoltage of a capacitor when the capacitor is precharged using a voltage conversion device that boosts power from a second power storage device, which has a lower voltage than that of a first power storage device.SOLUTION: In a control device of 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, while a capacitor is precharged by power from the second power storage device boosted by a second voltage conversion device in a state in which a relay between the first power storage device and a first voltage conversion device opens, a lower arm element of the first voltage conversion device is intermittently turned on and off such that a voltage difference between the first power storage device and the capacitor is within a predetermined range.SELECTED DRAWING: Figure 2

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, and an inverter that converts the DC voltage of the smoothing capacitor into an AC voltage and supplies it to a drive 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, and a first power storage device provided between the system main relay and the smoothing capacitor. Alternatively, it includes 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 Document 1). The control device of this electric system controls the bidirectional DC / DC converter to step up when it receives a start instruction by turning on the ignition switch, and when the voltage of the smoothing capacitor reaches the precharge completion threshold, both sides The boosting operation of the DC / DC converter is stopped and the system main relay is closed.

Japanese Unexamined Patent Publication No. 2007-318849

In the above-mentioned electric system, if the smoothing capacitor becomes overvoltage while being precharged by the bidirectional DC / DC converter, the precharge cannot be completed normally, or the smoothing capacitor or is connected to the smoothing capacitor. There is a risk that various auxiliary equipment may break down.

Therefore, in the present disclosure, when a capacitor is precharged by using a voltage conversion device that boosts the power from the second power storage device having a voltage lower than that of the first power storage device, the precharge is performed while suppressing the overvoltage of the capacitor. The main purpose is to complete it.

The power supply system of the present disclosure is 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, and is connected to the first power storage device via a relay on the positive side. A second power line including a power line and a negative side power line, an upper arm element connected to the positive side power line and a high voltage power line, and a lower arm element connected to the positive side power line and the negative side power line. A voltage converter, a capacitor connected to the positive side power line and the negative side power line between the relay and the first voltage converter, and the positive side power between the relay and the capacitor. It is connected to the line and the power line on the negative side, and the power from the first power storage device and the first voltage conversion device side is stepped down and supplied to the second power storage device side, and the power from the second power storage device is supplied. A second voltage conversion device that can be boosted and supplied to the first power storage device and the first voltage conversion device side, and the second voltage booster that is boosted by the second voltage conversion device with the relay opened. 2 While the capacitor is precharged by the electric power from the power storage device, the lower arm element of the first voltage conversion device is placed so that the voltage difference between the first power storage device and the capacitor is within a predetermined range. It includes a control device that turns on and off intermittently.

In the power supply system of the present disclosure, the voltage between the first power storage device and the capacitor is set while the capacitor is precharged by the power from the second power storage device boosted by the second voltage conversion device in the state where the relay is opened. The difference is monitored, and the lower arm element of the first voltage converter is intermittently turned on and off so that the voltage difference is within a predetermined range. As a result, even if an abnormality that causes an overvoltage of the capacitor occurs while the precharge is being executed, the voltage of the capacitor is adjusted to a value close to the voltage of the first power storage device by intermittently turning on and off the lower arm element. It becomes possible. Further, in such a power supply system, even if the second voltage converter boosts the power from the second power storage device to a relatively high constant voltage, for example, the capacitor is brought to a value close to the voltage of the first power storage device. Can be precharged. As a result, in the power supply system of the present disclosure, it is possible to complete the precharge of the capacitor while suppressing the overvoltage of the capacitor.

Further, in the control device, when the voltage difference between the first power storage device and the capacitor is out of the predetermined range and the voltage of the capacitor is equal to or more than the predetermined voltage, the voltage difference is within the predetermined range. The lower arm element of the first voltage conversion device may be intermittently turned on and off so as to be. As a result, the abnormality of the capacitor precharge by the second voltage converter is detected without using a dedicated abnormality detection circuit or the like, and when the abnormality is detected, the voltage of the capacitor is set to a value close to the voltage of the first power storage device. It is possible to complete the precharge by adjusting to.

Further, the power supply system connects the inverter connected to the high voltage power line and the negative voltage side power line, and the high voltage power line and the negative voltage side power line between the first voltage conversion device and the inverter. The control device may further include a second capacitor to be connected, and the control device turns on the upper arm element of the first voltage converter while the capacitor and the second capacitor are precharged. The lower arm element may be intermittently turned on and off in the state of being turned on. As a result, it is possible to complete the precharging of both the capacitor and the second capacitor using the second voltage converter while suppressing the overvoltage.

Further, the second voltage conversion device includes a voltage sensor that detects the output voltage of the second voltage conversion device and a control device that executes feedback control so that the detection value of the voltage sensor becomes a target voltage. It may be a thing. Further, the second voltage conversion device may boost the power from the second power storage device and output a predetermined constant voltage.

It is a schematic block diagram which shows the vehicle including the power supply system of this disclosure. It is a flowchart which shows an example of the routine executed by the control device of the power supply system of this disclosure. It is a time chart which shows the temporal change of the voltage of a capacitor while the routine of FIG. 2 is executed. It is a flowchart which shows an example of the other routine executed by the control device of the power supply system of this 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 the power supply system 1 of the present disclosure. In addition to the power supply system 1, the hybrid vehicle V shown in the figure includes an engine EG, a single pinion type planetary gear PG, motor generators MG1 and MG2 that exchange 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 are included. Further, the power supply system 1 includes a positive voltage side system main relay SMRB, a negative voltage side system main relay SMRG, and a positive electrode that are closed when an exciting current is supplied to a high voltage battery (first power storage device) 2 or a coil (not shown). Side and negative side system Power control device (hereinafter referred to as "PCU") 3 which is connected to the high voltage battery 2 via the main relays SMRB and SMRG and drives the motor generators MG1 and MG2, which is lower than the high voltage battery 2. It includes a low voltage battery (second power storage device) 4, a bidirectional DC / DC converter (second voltage converter) 5, and the like.

The engine EG is an internal combustion engine that generates power by explosive combustion of an air-fuel mixture of hydrocarbon fuels such as gasoline, light oil, and 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, and of the engine EG. Includes a planetary carrier connected to the crankshaft. The output shaft is connected to the left and right drive wheels DW via a differential gear DF and a drive shaft DS.

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

The HVECU 10 is a microcomputer including a CPU, ROM, RAM, etc. (not shown). The HVECU 10 is connected to an engine electronic control device or the like via a communication line 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 is running, the HVECU 10 sets the required torque required for running based on the accelerator opening and the vehicle speed, and also requires the power required for the engine EG, the target rotation speed, and the torque command values for the motor generators MG1 and MG2. Etc. are set.

Further, the HVECU 10 controls opening and closing of the positive electrode side system main relay SMRB and the negative electrode side system main relay SMRG. That is, when the start switch SS is turned on by the driver and the system activation of the hybrid vehicle V is requested, the HVECU 10 supplies an exciting current to a coil (not shown) of the positive electrode side system main relay SMRB and the negative electrode side system main relay SMRG. Both are closed (on), and the high voltage battery 2 and the PCU 3 are electrically connected. Further, when the start switch SS is turned off by the driver and the system of the hybrid vehicle V is requested to be stopped, the HVECU 10 cuts off the supply of the exciting current to the positive electrode side system main relay SMRB and the negative electrode side system main relay SMRG. Both are opened (off), and the electrical connection between the high-voltage battery 2 and the PCU 3 is released.

The high voltage battery 2 constituting 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 400 V. The positive electrode side power line PL is connected to the positive electrode terminal of the high voltage battery 2 via the positive electrode side system main relay SMRB, and the negative electrode side power is connected to the negative electrode terminal of the high voltage battery 2 via the negative electrode side system main relay SMRG. The line NL is connected. Further, the high voltage battery 2 is provided with a voltage sensor 21 for detecting the voltage VB between terminals of the high voltage battery 2 and a current sensor 22 for detecting the current (charge / discharge current) IB flowing through the high voltage battery 2. ing. The voltage VB between 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 via a signal line (not shown) or a power supply management electron (not shown) that manages the high-voltage battery 2. It is transmitted to the HVECU 10 by the control device.

The PCU3 constituting the power supply system 1 boosts the electric power from the first inverter 31 for driving the motor generator MG1, the second inverter 32 for driving the motor generator MG2, and the high voltage battery 2, and is on the motor generators MG1 and MG2 sides. A buck-boost converter (first voltage converter) 33 capable of stepping down the voltage from the inverter, and a motor electronic control unit (hereinafter referred to as "MGECU") for controlling the first and second inverters 31, 32 and the buck-boost converter 33. ) 30 and included.

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 opposite direction. It is a thing. The six transistors are paired with each other so as to be on the source side and the sink side with respect to the high voltage power line HPL and the negative electrode side power line NL. Further, each of the three-phase coils (U-phase, V-phase, W-phase) of the 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 to each transistor Tra and Trb in opposite directions, and a reactor L. .. One end of the reactor L is electrically connected to the power line PL on the positive electrode side, and the other end of the reactor L is an emitter of one transistor (upper arm element) Tra and a collector of the other transistor (lower arm element) Trb. Is electrically connected. Further, 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 electrode side power line NL.

Further, the PCU3 includes a filter capacitor (first capacitor) 34, a smoothing capacitor (second capacitor) 35, and voltage sensors 36 and 37. The positive electrode terminal of the filter capacitor 34 is electrically connected to the positive electrode side power line PL (one end of the reactor L) between the positive electrode side system main relay SMRB and the buck-boost converter 33, and the negative electrode terminal of the filter capacitor 34 is the negative electrode. Side system The main relay SMRG and the buck-boost converter 33 are electrically connected to the negative electrode side power line NL. As a result, the voltage on the high voltage battery 2 side of the buck-boost converter 33 (voltage applied to the buck-boost converter 33) is smoothed by the filter capacitor 34. Further, the voltage sensor 36 detects the voltage between terminals (voltage before boosting) VL of the filter capacitor 34.

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

The MGECU 30 is a microcomputer including a CPU, ROM, RAM, etc. (not shown), and is connected to the HVECU 10 and the like via a communication line such as a CAN. Further, the MG ECU 30 includes a command signal from the HVECU 10, a resolver detection value (not shown) that detects the rotation position of the rotor of the motor generator MG1, a resolver detection value that detects the rotation position of the rotor of the motor generator MG2, and a buck-boost converter 33. The current value from the current sensor (not shown), the voltage between terminals VL, VH from the voltage sensors 36 and 37, the phase current applied to the motor generators MG1 and MG2 detected by the current sensor (not shown), and the like are input. The MGECU 30 generates gate signals (switching control signals) to the first and second inverters 31, 32 and the buck-boost converter 33 based on these input signals, and switches and controls them.

The low-voltage battery 4 constituting 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 a low-voltage power line. The bidirectional DC / DC converter (DDC) 5 is connected to the positive electrode side power line PL between the positive electrode side system main relay SMRB and PCU3, and the negative electrode side power between the negative electrode side system main relay SMRG and PCU3. Connected to line NL. Further, the bidirectional DC / DC converter 5 is connected to the low voltage battery 4 and a plurality of auxiliary devices via the low voltage power line. In addition to the bidirectional DC / DC converter 5, high-voltage auxiliary equipment such as a compressor (inverter compressor) of an air conditioner and a converter to AC100V is connected to the positive electrode side power line PL and the negative electrode side power line NL. Will be done.

Then, the bidirectional DC / DC converter 5 lowers the electric power on the positive side power line PL side, that is, the high voltage battery 2 and the PCU 3 (boost pressure converter 33) side to the low voltage power line side, that is, various auxiliary machines and low voltage In addition to supplying the voltage battery 4, the power from the low voltage battery 4 can be boosted and supplied to the positive side power line PL side, that is, the high voltage battery 2 and the PCU 3. In the present embodiment, the bidirectional DC / DC converter 5 includes a voltage conversion circuit 50, a voltage sensor 51 that detects an output voltage to the high voltage battery 2 and the PCU 3 side of the voltage conversion circuit 50, and a low voltage conversion circuit 50. An electronic control device (hereinafter referred to as "DDCECU") that feedback-controls the voltage conversion circuit 50 so that the detection value of a voltage sensor, a voltage sensor 51, etc. (not shown) that detects the output voltage to the voltage battery 4 side becomes the target voltage Vtag. Including 55 mag. 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 DDCECU 55 via the communication line.

Next, the control procedure of the power supply system 1 when the start switch SS is turned on by the driver and the hybrid vehicle V is system-started will be described with reference to FIG. FIG. 2 is a flowchart showing an example of a routine executed by the HVECU 10 when the start switch SS is turned on and the system start of the hybrid vehicle V is requested. In the following description, the transistor Tra of the buck-boost converter 33 is referred to as "upper arm element Tra", and the transistor Trb is referred to as "lower arm element Trb".

When the start switch SS is turned on by the driver, the HVECU 10 (CPU) acquires the voltage VB between the terminals of the high voltage battery 2 detected by the voltage sensor 21 as shown in FIG. 2, and the filter capacitor 34 of the PCU3. The inter-terminal voltage VB is set as the target voltage Vtag when the smoothing capacitor 35 is precharged, and the set target voltage Vtag is transmitted to the DDCECU 55 of the bidirectional DC / DC converter 5 (step S100). The DDCECU 55 that has received the target voltage Vtag from the HVECU 10 is a voltage conversion circuit 50 that causes the detection value of the voltage sensor 51 to be the target voltage Vtag with the positive and negative system main relays SMRB and SMRG opened. When the feedback control is started and 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 inter-terminal voltage VB of the high-voltage battery 2 detected by the voltage sensor 21 and the inter-terminal voltage VL of the filter capacitor 34 detected by the voltage sensor 36, and inter-terminals. Whether or not the absolute value | VB-VL | of the difference between the voltage VB and the voltage VL between terminals is larger than a predetermined relatively small value α (positive value, for example, about 30 V) (from −α to + α). Whether or not it is outside the range (predetermined range) of (step S110). If it is determined in step S110 that the absolute value | VB-VL | is larger than the value α (step S110: YES), the HVECU 10 is predetermined after transmitting the target voltage Vtag to the DDCECU 55 in step S100. It is determined whether or not the time tref has elapsed (step S120). As the time tref as the threshold value used in step S120, the inter-terminal voltage VL of the filter capacitor 34 and the inter-terminal voltage VH of the smoothing capacitor 35 use the bidirectional DC / DC converter 5 after the target voltage Vtag is transmitted to the DDCECU 55. It is defined as the time during which the target voltage Vtag can be considered to have been reached due to the precharge.

If it is determined in step S120 that the time relay has not elapsed after the target voltage Vtag is transmitted to the DDCECU 55, the HVECU 10 executes the determination process of step S110 again, and in step S110, the absolute value | VB-VL | is set. When it is determined that the value is α or less (within the range from −α to + α) (step S110: NO), the HVECU 10 closes the positive electrode side system main relay SMRB and the negative electrode side system main relay SMRG (step S200). .. At this time, since the inter-terminal voltage VL of the filter capacitor 34 and the inter-terminal voltage VH of the smoothing capacitor 35 are close to the target voltage Vtag, that is, the inter-terminal voltage VB of the high-voltage battery 2, the positive side and the negative side When the system main relays SMRB and SMRG are closed, it is possible to suppress a large inrush current from flowing to the positive voltage side power line PL or the like or the PCU3. After the process of step S200, the HVECU 10 shifts the vehicle state to the READY-ON state in which the hybrid vehicle V is allowed to travel (step S210), and ends the routine of FIG.

On the other hand, when it is determined in step S110 that the absolute value | VB-VL | is larger than the value α, and in step S120, it is determined that the time tref has elapsed after the transmission of the target voltage Vtag to the DDCECU 55 (step S110, S120: YES), the HVECU 10 acquires the inter-terminal voltage VL of the filter capacitor 34 detected by the voltage sensor 36, and determines whether or not the inter-terminal voltage VL is equal to or greater than a predetermined overvoltage threshold (predetermined voltage) Vref. Determine (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 voltage of the filter capacitor 34, the smoothing capacitor 35, and the high voltage auxiliary machine.

When 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, the filter capacitor 34 is caused by an abnormality in the voltage conversion circuit 50 of the bidirectional DC / DC converter 5, the voltage sensor 51, the DDCECU 55, or the like. Is overcharged beyond the target voltage Vtag. Therefore, when it is determined in step S130 that the voltage VL between terminals is equal to or higher than the overvoltage threshold value Vref (step S130: YES), the HVECU 10 sends a command signal to the MGECU 30 to turn on the upper arm element Tra of the buck-boost converter 33. (ON command) is transmitted (step S140), and further, a command signal (ON / OFF command) is transmitted to the MGECU 30 so as to intermittently turn on / off the lower arm element Trb of the buck-boost converter 33 (step S150).

Upon receiving the command signals (ON command and ON / OFF command) from the HVECU 10, the MGECU 30 turns on the upper arm element Tra of the buck-boost converter 33, turns on the upper arm element Tra, and then turns on the voltage between the terminals VB and the terminals. The lower arm element Trb of the buck-boost converter 33 is intermittently turned on and off so that the absolute value | VB-VL | of the difference from the voltage VL is equal to or less than the value α. As a result, the inter-terminal voltage VL of the filter capacitor 34 and the inter-terminal voltage VH of the smoothing capacitor 35 are gradually applied while gradually flowing (releasing) the electric charges stored in the filter capacitor 34 and the smoothing capacitor 35 to the negative electrode side power line NL. Can be lowered.

After transmitting the command signal (ON / OFF command) to the MGECU 30 in step S150, the HVECU 10 determines whether or not the absolute value | VB-VL | is equal to or less than the value α at every minute time (step S160). Then, when it is determined that the absolute value | VB-VL | is equal to or less than the value α (step S160: YES), the HVECU 10 closes the positive electrode side system main relay SMRB and the negative electrode side system main relay SMRG (step S170). .. Also in this case, since the inter-terminal voltage VL of the filter capacitor 34 and the inter-terminal voltage VH of the smoothing capacitor 35 are close to the target voltage Vtag, that is, the inter-terminal voltage VB of the high-voltage battery 2, the positive and negative sides are positive and negative. Side system When the main relays SMRB and SMRG are closed, it is possible to suppress the flow of a large inrush current to the positive side power line PL and the like and the PCU3.

After the process of step S170, the HVECU 10 shifts the vehicle state to the READY-ON state, and at the same time, on an instrument panel or the like (not shown) to show that an abnormality has occurred in the precharge by the bidirectional DC / DC converter 5. The provided warning light is turned on (step S180). Further, the HVECU 10 transmits a command signal to the DDCECU 55 so as to stop the operation of the bidirectional DC / DC converter 5 at the timing when both the positive electrode side and the negative electrode side system main relays SMRB and SMRG are completely closed (step). S190), the routine of FIG. 2 is terminated. In the MGECU 30, the absolute value | VB-VL | becomes a value α or less due to the intermittent on / off control of the lower arm element Trb of the buck-boost converter 33, and in step S180, the positive electrode side and negative electrode side system main relays SMRB, SMRG. Absolute value | VB-VL from the time when the closing of the device is instructed (time t1 in FIG. 3) until the operation of the bidirectional DC / DC converter 5 is stopped in step S190 (time t2 in FIG. 3). Intermittent on / off control of the lower arm element Trb is continued so that | is maintained below the value α. Further, 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), in the HVECU 10, the bidirectional DC / DC converter 5 causes the low voltage battery 4 due to some abnormality. It is considered that the voltage from the voltage cannot be boosted, and a command signal is transmitted to the DDCECU 55 to stop the operation of the bidirectional DC / DC converter 5, and an abnormality occurs in the precharge by the bidirectional DC / DC converter 5. A warning light provided on an instrument panel or the like (not shown) is turned on to indicate that this has been done (step S220). Further, the HVECU 10 prohibits the operation of the bidirectional DC / DC converter 5 and the transition to the READY-ON state (step S230), and ends the routine of FIG.

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 used without using a dedicated abnormality detection circuit or the like. When the abnormality is detected, the upper arm element Tra of the buck-boost converter 33 is turned on, and the lower arm element Trb is intermittently turned on and off to connect the terminals of the filter capacitor 34. The voltage VL and the inter-terminal voltage VH of the smoothing capacitor 35 can be adjusted to values close to the inter-terminal voltage VB of the high-voltage battery 2 (within the range of VB ± α). As a result, when an abnormality in the precharge of the filter capacitor 34 and the smoothing capacitor 35 using the bidirectional DC / DC converter 5 occurs, the overvoltage of the filter capacitor 34 and the smoothing capacitor 35, that is, the filter capacitor 34, the smoothing capacitor 35, and It is possible to complete the precharging of the filter capacitor 34 and the smoothing capacitor 35 while satisfactorily suppressing the occurrence of failure of the high-voltage auxiliary machine connected to them.

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 a positive-side system main relay SMRB or a negative-side system main relay SMRG, respectively. The positive side power line PL and the negative side power line NL connected to the high voltage battery 2 via the above, the upper arm element Tra connected to the positive side power line PL and the high voltage power line HPL, and the positive side power line PL. The buck-boost converter 33 including the lower arm element Trb connected to the negative-voltage side power line NL, and the positive-side power line PL and the negative-voltage converter 33 between the positive-side and negative-side system main relays SMRB, SMRG and the buck-boost converter 33. A high-voltage battery connected to the positive side power line PL and the negative side power line NL between the filter capacitor 34 connected to the side power line NL and the positive and negative side system main relays SMRB, SMRG and the filter capacitor 34. 2. The power from the buck-boost converter 33 side can be stepped down and supplied to the low-voltage battery 4, and the power from the low-voltage battery 4 can be boosted and supplied to the high-voltage battery 2 and the buck-boost converter 33 side. Includes a bidirectional DC / DC converter 5 capable of being capable, and an HVECU 10 as a control device. The HVECU 10 is used while the filter capacitor 34 is precharged by the power from the low-voltage battery 4 boosted by the bidirectional DC / DC converter 5 with the positive and negative system main relays SMRB and SMRG open. , The lower arm element of the buck-boost converter 33 so that the voltage difference | VB-VL | between the high voltage battery 2 and the filter capacitor 34 is within a predetermined range (range from −α to + α) in cooperation with the MGECU 30. The Trb is turned on and off intermittently (step S150). As a result, when an abnormality in the precharge of the filter capacitor 34 using the bidirectional DC / DC converter 5 occurs, the precharge of the filter capacitor 34 is completed while satisfactorily suppressing the overvoltage of the filter capacitor 34. Is possible.

Further, the power supply system 1 is located between the first and second inverters 31 and 32 connected to the high voltage power line HPL and the negative power line NL, and between the buck-boost converter 33 and the first and second inverters 31 and 32. Includes a smoothing capacitor 35 connected to the high voltage power line HPL and the negative side power line NL. Further, the HVECU 10 intermittently shifts the lower arm element Trb in a state where the upper arm element Tra of the buck-boost converter 33 is turned on in cooperation with the MGECU 30 while the filter capacitor 34 and the smoothing capacitor 35 are precharged. (Steps S140, S150). This makes it possible to complete the precharging of both the filter capacitor 34 and the smoothing capacitor 35 using the bidirectional DC / DC converter 5 while suppressing the overvoltage.

In addition, in the HVECU 10, the voltage difference | VB-VL | between the high voltage battery 2 and the filter capacitor 34 is out of the predetermined range (range from −α to + α), and the voltage VL between the terminals of the filter capacitor 34 is overvoltage. When the threshold (predetermined voltage) Vref or more (steps S110, S120, S130; YES), the lower arm element Trb of the buck-boost converter 33 is intermittently set so that the voltage difference | VB-VL | is within the predetermined range. (Step S150). As a result, an abnormality in the precharge of the filter capacitor 34 and the smoothing capacitor 35 by the bidirectional DC / DC converter 5 is detected without using a dedicated abnormality detection circuit or the like, and when the abnormality is detected, the terminal of the filter capacitor 34 is detected. It is possible to complete the precharge by adjusting the inter-terminal voltage VL and the inter-terminal voltage VH of the smoothing capacitor 35 to values close to the inter-terminal voltage VB of the high-voltage battery 2.

Even if the smoothing capacitor 35 of the PCU 3 is charged by the bidirectional DC / DC converter 5 to a voltage higher than the terminal voltage VB of the high voltage battery 2, there is a practical problem after the vehicle state shifts to the READY-ON state. Will not occur. Therefore, the process of step S140 in FIG. 2 may be omitted, and in step S150, the lower arm element Trb may be intermittently on / off controlled with the upper arm element Tra of the buck-boost converter 33 turned off. Further, in step S130 of FIG. 2, instead of the inter-terminal voltage VL of the filter capacitor 34, the inter-terminal voltage VH of the smoothing capacitor 35 may be compared with the overvoltage threshold Vref.

Further, the bidirectional DC / DC converter 5 described above feedback-controls the voltage conversion circuit 50 so that the detected value of the voltage sensor 51 becomes the target voltage Vtag set by the HVECU 10. The converter 5 may boost the power from the low-voltage battery 4 and output a predetermined constant voltage higher than the rated voltage of the high-voltage battery 2, for example. In the power supply system 1 in which such a bidirectional DC / DC converter 5 is adopted, the filter capacitor 34 and the smoothing capacitor 35 can be precharged according to the procedure shown in FIG.

That is, when the routine of FIG. 4 is executed in response to the driver turning on the start switch SS, the HVECU 10 transmits a precharge start command to the DDCECU 55 (step S300). Subsequently, the HVECU 10 transmits a command signal (ON command) to the MGECU 30 so as to turn on the upper arm element Tra of the buck-boost converter 33 (step S310). A command signal (ON / OFF command) is transmitted to the MGECU 30 so as to intermittently turn on / off the lower arm element Trb of the buck-boost converter 33 (step S320). After the process of step S320, the HVECU 10 sets the absolute value | VB-VL | of the difference between the terminal voltage VB of the high voltage battery 2 and the terminal voltage VL of the filter capacitor 34 to the value α or less every minute time. It is determined whether or not (step S330).

When it is determined that the absolute value | VB-VL | is equal to or less than the value α (step S330: YES), the HVECU 10 closes the positive electrode side system main relay SMRB and the negative electrode side system main relay SMRG (step S340). Further, the HVECU 10 shifts the vehicle state to the READY-ON state in which the hybrid vehicle V is allowed to travel (step S350), and sends a command signal to the DDCECU 55 so as to stop the operation of the bidirectional DC / DC converter 5. Transmission (step S360) to end the routine of FIG. In the routine of FIG. 4, the process of step S310 may be omitted. Further, the precharge abnormality detection step included in FIG. 2 may be incorporated into the routine of FIG.

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 type hybrid vehicle, a series type hybrid vehicle, a parallel type hybrid vehicle, or a plug-in type. It may be a hybrid vehicle or an electric vehicle. Further, the PCU3 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 embodiment, and various changes can be made within the scope of the extension of the present disclosure. Further, the form for carrying out the above invention is merely a specific form of the invention described in the column of means for solving the problem, and is described in the column of means for solving the problem. It does not limit the elements of the invention.

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

1 Power supply system, 2 High voltage battery, 3 Power controller (PCU), 4 Low voltage battery, 5 Bidirectional DC / DC converter, 50 Voltage conversion circuit, 55 Electronic controller (DDCECU), 10 Hybrid electronic controller (HVECU) ) 21,36,37,51 Voltage sensor, 22 Current sensor, 30 Motor electronic controller (MGECU), 31 1st inverter, 32 2nd inverter, 33 buck-boost converter, 34 filter capacitor, 35 smoothing capacitor, Da, Db capacitor, DF differential gear, DS drive shaft, DW drive wheel, EG engine, HPL high voltage power line, L inverter, MG1, MG2 motor generator, NL negative side power line, PG planetary gear, PL positive side power line, SMRB positive side 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 electrode side power line and a negative electrode side power line connected to the first power storage device via a relay, respectively.
A first voltage converter including an upper arm element connected to the positive side power line and the high voltage power line, and a lower arm element connected to the positive side power line and the negative side power line.
A capacitor connected to the positive electrode side power line and the negative electrode side power line between the relay and the first voltage conversion device, and
The relay and the capacitor are connected to the positive electrode side power line and the negative electrode side power line, and the power from the first power storage device and the first voltage conversion device side is stepped down to reduce the power from the second power storage device side. A second voltage converter that can boost the power from the second power storage device and supply it to the first power storage device and the first voltage conversion device side.
The voltage difference between the first power storage device and the capacitor while the capacitor is precharged by the power from the second power storage device boosted by the second voltage conversion device in the state where the relay is opened. A power supply system including a control device that intermittently turns on and off the lower arm element of the first voltage conversion device so that the voltage is within a predetermined range.

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