JP2020145869A - Power system - Google Patents

Abstract

To determine securely and promptly the existence or non-existence of welding in a positive electrode side relay, connected to a positive electrode terminal of a power storage device, and a negative electrode side relay, connected to the negative electrode terminal.SOLUTION: In a power system, when a system halt is requested, the upper arm element and the lower arm element of the voltage conversion device are switched off, and in a state that one of the positive electrode side and the negative electrode side relays is opened and the other is closed, the lower arm element is intermittently switched on and off, so that the existence or non-existence of welding on one of the positive electrode side and the negative electrode side relays is determined. When the one is determined to have no welding, a first capacitor is precharged by a precharge device, and in a state that one of the positive electrode side and the negative electrode side relays is closed and the other is opened, the lower arm element or an inverter is operated to discharge the first capacitor, so that the existence or non-existence of welding on the other of the positive electrode side and the negative electrode side relays is determined.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a power supply system including a power storage device.

Conventionally, between the first DC power supply, the first relay connected between one pole of the first DC power supply and the first power line, and the other pole of the first DC power supply and the second power line. A second relay connected to, a capacitor connected between the first and second power lines, and a bidirectional DC / DC converter connected in parallel with the capacitor between the first and second power lines. , The second DC power supply connected to the bidirectional DC / DC converter and the first and second relays are turned off and on, respectively, and the bidirectional DC / DC converter is controlled so as to discharge the capacitor. A vehicle load drive device including a control device is known (see, for example, Patent Document 1). When the ignition key of the vehicle is turned off, the control device of this load drive device turns off one of the first and second relays and drives a bidirectional DC / DC converter to discharge the capacitor. The control device performs a welding check of one of the first and second relays based on the detection value of the current sensor that detects the current output from the first DC power supply. After the welding check, the controller drives the bidirectional DC / DC converter to recharge the capacitor, turns off only the other of the first and second relays, and drives the bidirectional DC / DC converter to discharge the capacitor. Then, the welding of the other of the first and second relays is checked.

Japanese Unexamined Patent Publication No. 2007-252082

However, even if the bidirectional DC / DC converter is driven to decharge the capacitor as described above, the second DC power supply is charged by the power from the capacitor side as the voltage of the capacitor approaches the voltage of the second DC power supply. I can't do it. Therefore, in the above-mentioned conventional load drive device, the voltage of the capacitor cannot be sufficiently lowered by the bidirectional DC / DC converter, and it becomes impossible to determine the presence or absence of welding of the first and second relays. is there.

Therefore, it is a main object of the present disclosure to make it possible to more reliably and quickly determine the presence or absence of welding of the positive electrode side relay connected to the positive electrode terminal and the negative electrode side relay connected to the negative electrode terminal of the power storage device.

The power supply system of the present disclosure is a power supply system including a power storage device, which connects to a positive power line connected to a positive terminal of the power storage device via a positive side relay and a negative terminal of the power storage device via a negative side relay. A voltage including a negative side power line to be connected, 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. The conversion device, the inverter connected to the high voltage power line and the negative side power line, and the positive side relay and the voltage conversion device connected to the positive side power line and the negative side relay. A first capacitor connected to the negative side power line between the voltage converter and the high voltage power line and the negative side power line are connected between the first voltage converter and the inverter. The second capacitor, the precharge device capable of precharging the first and second capacitors, and the upper arm element and the lower arm element of the voltage conversion device are turned off when the system stop is requested, and the above. Whether the voltage of the first capacitor becomes equal to or higher than a predetermined value after the lower arm element is intermittently turned on and off with one of the positive side relay and the negative side relay opened and the other closed. Alternatively, when a current flows from the power storage device to the voltage conversion device side, it is determined that one of the positive side relay and the negative side relay is welded, and when it is determined that one of them is not welded, the said The lower arm element so as to precharge the first capacitor in a precharging device, and discharge the first capacitor in a state where one of the positive side relay and the negative side relay is closed and the other is opened. Alternatively, when the voltage of the first capacitor becomes equal to or higher than a predetermined value after the inverter is operated, or when a current flows from the power storage device to the voltage conversion device side, the positive side relay and the negative side relay of the other side. It includes a relay welding determination device for determining that the welding is done.

In the power supply system of the present disclosure, when a system stop is requested, the upper arm element and the lower arm element of the voltage converter are turned off, one of the positive electrode side relay and the negative electrode side relay is opened and the other is closed. The lower arm element is intermittently turned on and off in the formed state. As a result, if the first capacitor is discharged and one of the positive electrode side relay and the negative electrode side relay is not welded, no current flows from the power storage device to the voltage conversion device side, and the voltage of the first capacitor becomes less than a predetermined value. .. Therefore, when the voltage of the first capacitor exceeds a predetermined value after the lower arm element is intermittently turned on and off, or when a current flows from the power storage device to the voltage converter side, one of the positive electrode side relay and the negative electrode side relay It is determined that they are welded. On the other hand, when it is determined that one of the positive electrode side relay and the negative electrode side relay is not welded, the first capacitor is precharged by the precharging device. Then, after operating the lower arm element or the inverter so as to discharge the first capacitor in a state where one of the positive electrode side relay and the negative electrode side relay is closed and the other is opened, the voltage of the first capacitor becomes a predetermined value. If the above results or a current flows from the power storage device to the voltage conversion device side, it is determined that the other of the positive electrode side relay and the negative electrode side relay is welded.

In such a power supply system, the voltage of the first capacitor can be sufficiently lowered when determining the welding of the positive electrode side relay and the negative electrode side relay. Further, when determining the welding of one of the positive electrode side relay and the negative electrode side relay, which is executed first, the lower arm element is intermittently turned on and off while the upper arm element of the voltage converter is turned off, so that the second capacitor is used. It is possible to discharge only the first capacitor without discharging the first capacitor, and the subsequent precharging of the first capacitor can be completed quickly. As a result, it becomes possible to more reliably and quickly determine whether or not the positive electrode side relay and the negative electrode side relay are welded.

Further, the control device turns off the lower arm element of the voltage conversion device after intermittently turning on / off the lower arm element and before precharging the first capacitor in the precharging device. , The upper arm element may be turned on. As a result, the first capacitor can be charged with the electric charge stored in the second capacitor before the precharging of the first capacitor, and the time required for precharging the first capacitor can be further shortened. As a result, it becomes possible to more quickly determine the presence or absence of welding of the positive electrode side relay and the negative electrode side relay.

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.

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 off by the driver and the hybrid vehicle V is system-stopped will be described with reference to FIGS. 2 and 3.

FIG. 2 is a flowchart showing an example of a routine executed by the HVECU 10 when the start switch SS is turned off and the system stop of the hybrid vehicle V is requested, and FIG. 3 is a flowchart showing an example of the routine executed by the HVECU 10 while the routine of FIG. 2 is executed. It is a time chart which shows the time change of the voltage VL between terminals of the filter capacitor 34 of. 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". At the time when the start switch SS is turned off, both the positive electrode side and the negative electrode side system main relays SMRB and SMRG may be closed, or at least one of them may be opened.

When the start switch SS is turned off by the driver, the HVECU 10 (CPU) sends a command signal (OFF) to the MGECU 30 to turn off the upper arm element Tra and the lower arm element Trb of the buck-boost converter 33, as shown in FIG. A command) is transmitted (step S100), and the supply of exciting current to the positive electrode side system main relay SMRB is cut off (instructed to open) so that the positive electrode side system main relay SMRB (only) is opened (step S110). ). Subsequently, the HVECU 10 transmits a command signal (ON / OFF command) to the MGECU 30 so as to intermittently turn on / off the lower arm element Trb of the buck-boost converter 33 at the timing when the positive electrode side system main relay SMRB is completely opened. (Step S120). Upon receiving the command signal (ON / OFF command) from the HVECU 10, the MG ECU 30 intermittently turns on / off the lower arm element Trb of the buck-boost converter 33 while keeping the upper arm element Tra of the buck-boost converter 33 off.

After the process of step S120, the HVECU 10 acquires the inter-terminal voltage VL of the filter capacitor 34 detected by the voltage sensor 36 when a predetermined time elapses, and the inter-terminal voltage VL is a relatively small threshold value Vref set in advance. It is determined whether or not it is less than (for example, about 50 V) (step S130). Here, when only the positive electrode side system main relay SMRB is opened and the upper arm element Tra of the buck-boost converter 33 is turned off and the lower arm element Trb is intermittently turned on and off, it is stored in the filter capacitor 34. The charged charge flows through the reactor L to the negative electrode side power line NL to discharge the filter capacitor 34 (see time t1-t2 in FIG. 3). On the other hand, when the positive electrode side system main relay SMRB is welded (on failure), the current from the high voltage battery 2 is applied to the filter capacitor 34 even if the lower arm element Trb is intermittently turned on and off. As a result, the voltage between terminals VL does not decrease.

Therefore, when the voltage VL between the terminals of the filter capacitor 34 is equal to or higher than the threshold value Vref (step S130: NO), the HVECU 10 determines that the positive electrode side system main relay SMRB is welded (on failure), and the next system In response to the start request (on of the start switch SS), the fail-safe mode flag is turned on to indicate the start in the fail-safe mode (step S135). Further, the HVECU 10 shifts the vehicle state from the READY-ON state (travelable state) to the READY-OFF state (travel prohibition state) (step S230), and ends 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 threshold value Vref and the positive electrode side system main relay SMRB is not welded (step S130: YES), the HVECU 10 is the buck-boost converter 33. A command signal (OFF command) is transmitted to the MGECU 30 to turn off the lower arm element Trb (step S140), and a command signal (ON command) is sent to the MGECU 30 to turn on the upper arm element Tra of the buck-boost converter 33. Is transmitted (step S150). Upon receiving the command signals (OFF command and ON command) from the HVECU 10, the MGECU 30 turns off the lower arm element Tr of the buck-boost converter 33 and further turns on the upper arm element Tra.

As described above, after the processing of step S100 is executed, the smoothing capacitor 35 is discharged because the upper arm element Tra of the buck-boost converter 33 is turned off while the welding determination of the positive electrode side system main relay SMRB is executed. However, the inter-terminal voltage VH of the smoothing capacitor 35 is basically maintained higher than the inter-terminal voltage VL of the discharged filter capacitor 34. Therefore, when the lower arm element Trb of the buck-boost converter 33 is turned off and the upper arm element Tra is turned on in response to the processing of steps S140 and S150, the electric charge stored in the smoothing capacitor 35 flows into the filter capacitor 34. As a result, the filter capacitor 34 is charged (see time t3-t4 in FIG. 3).

When a predetermined time elapses after the process of step S150, the HVECU 10 acquires the inter-terminal voltage VB of the high voltage battery 2 detected by the voltage sensor 21 and sets the target voltage Vtag at the time of precharging the filter capacitor 34. The terminal voltage VB is set, and the set target voltage Vtag is transmitted to the DDCECU 55 of the bidirectional DC / DC converter 5 (step S160). Upon receiving the target voltage Vtag from the HVECU 10, the DDCECU 55 starts feedback control of the voltage conversion circuit 50 so that the detected value of the voltage sensor 51 becomes the target voltage Vtag, and when the detected value of the voltage sensor 51 reaches the target voltage Vtag. , The feedback control is stopped.

After transmitting the target voltage Vtag to the DDCECU 55 in step S160, the HVECU 10 determines whether or not the inter-terminal voltage VL of the filter capacitor 34 has reached the target voltage Vtag every minute time (step S170), and determines whether or not the inter-terminal voltage VL has reached the target voltage Vtag. When it is determined that the VL has reached the target voltage Vtag (step S170: YES), the positive system main relay SMRB is closed (step S180). Further, the HVECU 10 cuts off the supply of the exciting current to the negative electrode side system main relay SMRG (instructs the opening) so that the negative electrode side system main relay SMRG is opened (step S190), and determines the motor generators MG1 and MG2 in advance. A command signal (switching command) is transmitted to the MGECU 30 so that only the d-axis current flows through one or both of them (step S200).

Upon receiving the command signal (switching command) from the HVECU 10, the MG ECU 30 turns on the upper arm element Tra of the buck-boost converter 33 so that the d-axis current flows through one or both of the motor generators MG1 and MG2. Switching control is performed on at least one of the transistors of the first and second inverters 31 and 32. As a result, the electric charge stored in the filter capacitor 34 and the smoothing capacitor 35 can be supplied to the motor generator MG1 or the like as a d-axis current to be converted into heat, and the filter capacitor 34 and the smoothing capacitor 35 can be quickly discharged.

After the process of step S200, the HVECU 10 acquires the inter-terminal voltage VL of the filter capacitor 34 detected by the voltage sensor 36 when a predetermined time elapses, and whether or not the inter-terminal voltage VL is less than the above threshold value Vref. Is determined (step S210). When it is determined in step S210 that the voltage VL between terminals is equal to or higher than the threshold value Vref (step S210: NO), the current from the high-voltage battery 2 is the filter capacitor even though the filter capacitor 34 is discharged. By applying the voltage to 34, the voltage VL between terminals does not decrease. Therefore, when the voltage between terminals VL is equal to or higher than the threshold value Vref (step S210: NO), the HVECU 10 determines that the negative side system main relay SMRG is welded (on failure), and requests the next system start (start). The fail-safe mode flag is turned on to indicate the start in the fail-safe mode in response to the switch SS being turned on (step S215). Further, the HVECU 10 shifts the vehicle state from the READY-ON state (travelable state) to the READY-OFF state (travel prohibition state) (step S230), and ends the routine of FIG.

On the other hand, when it is determined in step S210 that the voltage VL between terminals is less than the above threshold value Vref and the negative electrode side system main relay SMRG is not welded (step S210: YES), the HVECU 10 is the positive electrode side system main. The relay SMRB is opened (step S220). Then, the HVECU 10 shifts the vehicle state from the READY-ON state (travelable state) to the READY-OFF state (travel prohibition state) (step S230), and ends the routine of FIG.

As described above, in the power supply system 1 in which the routine of FIG. 2 is executed by the HVECU 10, the voltage VL between the terminals of the filter capacitor 34 can be sufficiently lowered when determining the welding of the positive electrode side and negative electrode side system main relays SMRB and SMRG. It will be possible. That is, in the power supply system 1, the voltage VL between terminals cannot be sufficiently lowered as in the case where the filter capacitor 34 is discharged by using the bidirectional DC / DC converter 5. Further, when the welding determination of the positive electrode side system main relay SMRB to be executed earlier is performed, the lower arm element Trb is intermittently turned on / off while the upper arm element Tra of the buck-boost converter 33 is turned off (step S120). Only the filter capacitor 34 can be discharged without discharging the smoothing capacitor 35. As a result, when the filter capacitor 34 is precharged according to the process of step S160, the need for charging the smoothing capacitor 35 can be eliminated or reduced, and the precharge of the filter capacitor 34 can be completed promptly. Can be made to. As a result, in the power supply system 1, it is possible to more reliably and quickly determine whether or not the positive electrode side and negative electrode side system main relays SMRB and SMRG are welded.

Further, in the power supply system 1, the lower arm element Trb of the buck-boost converter 33 is turned off after the lower arm element Trb of the buck-boost converter 33 is intermittently turned on and off and before the precharge of the filter capacitor 34. At the same time, the upper arm element Tra is turned on (steps S140 and S150). As a result, the filter capacitor 34 can be charged with the electric charge stored in the smoothing capacitor 35 before the filter capacitor 34 is precharged, and the time required for precharging the filter capacitor 34 can be further shortened. Further, in the power supply system 1, at least one of the first and second inverters 31 and 32 is discharged so as to discharge the smoothing capacitor 35 in addition to the filter capacitor 34 when the welding determination of the negative electrode side system main relay SMRG is executed later. Is switched and controlled (step S200). As a result, it is not necessary to discharge the smoothing capacitor 35 after the processing in step S230, so that the processing efficiency can be improved.

As described above, the power supply system 1 of the present disclosure includes the high voltage battery 2, the positive power line PL connected to the positive terminal of the high voltage battery 2 via the positive system main relay SMRB, and the negative side system. The negative side power line NL connected to the negative terminal of the high voltage battery 2 via the main relay SMRG, the upper arm element Tr 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 side power line NL, the first and second inverters 31 and 32 connected to the high voltage power line HPL and the negative side power line NL, and the positive side. A filter capacitor connected to the positive side power line PL between the side system main relay SMRB and the buck-boost converter 33 and connected to the negative side power line NL between the negative side system main relay SMRG and the buck-boost converter 33. The smoothing capacitor 35 connected to the high voltage power line HPL and the negative side power line NL between the buck-boost converter 33 and the first and second inverters 31 and 32, and the filter capacitor 34 and the smoothing capacitor 35 are pre-mixed. It includes a chargeable bidirectional DC / DC converter 5 and an HVECU 10 as a welding determination device.

When the system stop is requested, the HVECU 10 turns off the upper arm element Tra and the lower arm element Trb of the buck-boost converter 33, opens one of the positive electrode side and negative electrode side system main relays SMRB and SMRG, and closes the other. When the voltage VL between the terminals of the filter capacitor 34 becomes equal to or higher than the threshold Vref after the lower arm element Trb is intermittently turned on and off in the formed state, one of the positive electrode side and negative electrode side system main relays SMRB and SMRG is welded. (Steps S100-S135). Further, when it is determined that one of the positive electrode side and negative electrode side system main relays SMRB and SMRG is not welded, the HVECU 10 precharges the filter capacitor 34 in the bidirectional DC / DC converter 5 to precharge the positive electrode side and negative electrode side systems. The voltage between the terminals of the filter capacitor 34 after operating at least one of the first and second inverters so as to discharge the filter capacitor 34 with one of the main relays SMRB and SMRG closed and the other open. When the VL has a threshold voltage Vref equal to or higher than the threshold voltage Vref, it is determined that the other of the positive electrode side and the negative electrode side system main relays SMRB and SMRG are welded (steps S160-S215). As a result, in the power supply system 1, it is possible to more reliably and quickly determine whether or not the positive electrode side and negative electrode side system main relays SMRB and SMRG are welded.

In steps S130 and S210 of FIG. 2, instead of comparing the inter-terminal voltage VL of the filter capacitor 34 with the threshold value Vref, a current is applied from the high voltage battery 2 to the buck-boost converter 33 side based on the detected value of the current sensor 22. May be determined whether or not Further, in step S200, both the upper arm element Tra and the lower arm element Trb of the buck-boost converter 33 may be turned on to discharge both the filter capacitor 34 and the smoothing capacitor 35, and the lower arm element of the buck-boost converter 33 may be discharged. Only Trb may be turned on and only the filter capacitor 34 may be discharged. Further, in the routine of FIG. 2, the processes of steps S140 and S150 may be omitted, and in this case, the start of precharging of the filter capacitor 34 may be instructed when a positive determination is made in step S130 (in this case). See the alternate long and short dash line in FIG. 3). Further, in the routine of FIG. 2, the order of welding determination of the positive electrode side and negative electrode side system main relays SMRB and SMRG may be changed.

Further, in the power supply system 1, the bidirectional DC / DC converter 5 may be replaced with a DC / DC converter having no function of stepping down the power from the high voltage battery 2 and the buck-boost converter 33, in this case. For example, a precharge circuit including a precharge relay and a resistor may be incorporated in parallel with the negative side system main relay SMRG for the negative side power line NL. In a power supply system including such a precharge circuit, the precharge relay may be closed in step S160 to precharge the filter capacitor 34 with the electric power from the high voltage battery 2.

Further, the vehicle including the above-mentioned power supply system 1 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 power storage device
A positive electrode side power line connected to the positive electrode terminal of the power storage device via a positive electrode side relay, and
A negative electrode side power line connected to the negative electrode terminal of the power storage device via a negative electrode side relay, and
A voltage conversion device 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.
An inverter connected to the high voltage power line and the negative electrode side power line,
A first capacitor connected to the positive electrode side power line between the positive electrode side relay and the voltage conversion device and connected to the negative electrode side power line between the negative electrode side relay and the voltage conversion device.
A second capacitor connected to the high voltage power line and the negative electrode side power line between the first voltage converter and the inverter.
A precharging device capable of precharging the first and second capacitors, and
When the system stop was requested, the upper arm element and the lower arm element of the voltage converter were turned off, and one of the positive electrode side relay and the negative electrode side relay was opened and the other was closed. When the voltage of the first capacitor becomes a predetermined value or more after the lower arm element is intermittently turned on and off in this state, or when a current flows from the power storage device to the voltage conversion device side, the positive electrode side relay and the above. It is determined that one of the negative electrode side relays is welded,
When it is determined that one of them is not welded, the precharging device is precharged with the first capacitor, and one of the positive electrode side relay and the negative electrode side relay is closed and the other is opened. When the voltage of the first capacitor becomes a predetermined value or more after operating the lower arm element or the inverter so as to discharge the first capacitor, or a current flows from the power storage device to the voltage conversion device side. A power supply system including a relay welding determination device for determining that the other of the positive electrode side relay and the negative electrode side relay is welded.

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