JP2005229699A - Power system for vehicle equipped with self-protecting functions - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restore voltage to its usual value at an early stage, if abnormality is dissolved, even if the voltage of a high-voltage power source goes up and a self-protecting circuit is actuated. <P>SOLUTION: The power system for a vehicle is equipped with a high-voltage power source 3, power converters 8 and 4 which are connected to this high-voltage power source, and a controller 11 which controls this power converter. The above power converter is equipped with a self-protecting function of stopping the drive, when the voltage of the above high-voltage power source is excessive, and the controller is equipped with a function of canceling the stop state by the self-protecting function of the power converter. This canceling function is executed when the abnormality of the system is dissolved, after actuation of the self-protecting function. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle power supply system, and more particularly to a vehicle power supply system in which a power converter connected to a high voltage power supply has a self-protection function.

  In a vehicle power supply system for using electric energy as a vehicle drive source, if the high-voltage power supply reaches an overvoltage due to some abnormality, the drive of the power converter is stopped by a protection function, and then driven if the overvoltage state is removed What is known to resume.

For example, Japanese Patent Laid-Open No. 1-202101 includes a DC motor for driving a vehicle, a battery that supplies driving power to the motor, and a chopper that controls driving power supplied from the battery to the DC motor. It is disclosed that the operation of the chopper is stopped when the voltage of the power circuit system reaches a predetermined voltage during braking.
JP-A-1-202101

  However, the self-protection function in the conventional vehicle power supply system often has a simple function of stopping when it exceeds the set voltage and returning when it falls below the set voltage. On the other hand, the high voltage system for driving has high impedance when the power converter is stopped, and it takes a long time, for example, several minutes or more for the voltage that has risen above the overvoltage determination value to drop. Therefore, during this time, even if the abnormality that caused the overvoltage is restored to the normal state, the vehicle cannot travel. Further, if the impedance at the time of stoppage is lowered due to the early drop of the voltage, it flows as a leakage current even when the system is normal, so that the power loss increases.

  Even if the self-protection circuit is activated due to an increase in the voltage of the high-voltage power supply, an object of the present invention is to enable the voltage to be restored to a normal value as soon as the abnormality is removed.

  In order to solve the above problems, a vehicle power supply system of the present invention is for a vehicle including a high-voltage power supply, a power converter connected to the high-voltage power supply, and a control device that controls the power converter. In the power supply system, the power conversion device includes a self-protection function that stops driving when the voltage of the high-voltage power supply is excessive, and the control device releases a stop state by the self-protection function of the power conversion device It has a function.

  By forcibly canceling the stop state of the power conversion device, the voltage of the high-voltage power supply can be lowered early.

  In the power supply system, the control device diagnoses an abnormality of the system when the power conversion device is stopped by the self-protection function, and if the abnormality is not detected, the control device sets the stop state of the power conversion device. It is desirable to cancel. Since the presence / absence of an abnormality is confirmed, safety can be ensured even if the suspension is forcibly released in preference to the self-protection function of the power converter.

  In particular, in a power supply system mounted on a moving body, an early return from a stopped state of the power conversion device is desired in order to satisfy the driving demand of the driver, and the system abnormality is diagnosed after the power conversion device is stopped. It will be possible to fulfill its purpose.

  The power supply system may further include a power storage device connected to the power conversion device, and the control device may release the stop state of the power conversion device. As a result, the high voltage can be lowered at an early stage, and power can be stored.

  In the power supply system, it is preferable that the control device sets the voltage control target value of the power conversion device to a maximum voltage in a normal range when releasing the stop state. As a result, the voltage can be smoothly lowered to the normal range.

  In the power supply system, the control device determines whether or not the voltage of the high-voltage power supply decreases after canceling the stop state of the power conversion device, and when it does not decrease, the drive of the power conversion device is stopped again. It is desirable to make it. If the voltage of the high-voltage power supply does not decrease even if the power converter is released from the stop state, there is a possibility of an abnormality. Therefore, the safety can be improved by stopping the power converter again.

  The “high voltage power supply” is not limited, but corresponds to a fuel cell, for example. And in the said invention, you may provide the load apparatus which consumes the electric power generated with the fuel cell etc. As an example of this load device, an auxiliary device (compressor, pump, etc.) of a fuel cell, or a power consuming device in which a drive motor or a vehicle electrical component or the like works as a load device in a fuel cell system mounted on a moving body Become.

  According to the present invention, even if the voltage of a high voltage power supply rises and the self-protection circuit is activated, it is possible to provide a vehicle power supply system that can quickly return the voltage to a normal value when the abnormality is removed. be able to.

Next, embodiments of the present invention will be described with reference to the drawings.
<1. Configuration of device>
FIG. 1 is a schematic configuration diagram of a vehicle power supply system according to an embodiment of the present invention. This vehicle power supply system is configured by connecting a DC / DC converter 8 as a power converter and a traction inverter 4 as a power converter in parallel to a fuel cell 3 as a high voltage power source. The DC / DC converter 8 is connected to the battery 1 as a power storage device, and the inverter 4 is connected to the drive motor 7.

  The fuel cell 3 is a device that generates electricity by an electrochemical reaction between hydrogen and oxygen. The auxiliary machine 2 is, for example, an air compressor, a hydrogen pump, a cooling water pump or the like, and operates by receiving power supply from the battery 1.

  The DC / DC converter 8 includes a switching circuit unit 9 and an overvoltage determination unit 10. The switching circuit unit 9 is a DC voltage converter that adjusts the DC voltage input from the battery 1 and outputs it to the inverter 4 side, and adjusts the DC voltage input from the fuel cell 3 or the drive motor 7. A function of supplying to the battery 1. The overvoltage determination unit 10 is connected to a terminal on the inverter 4 side of the switching circuit unit 9. When a predetermined overvoltage is detected, a drive stop signal SG1 is output to the switching circuit unit 9, and the DC / DC converter 8 performs a self-protecting function. The battery 1 may be a secondary battery or a capacitor as long as it can be charged and discharged.

  The inverter 4 includes a switching circuit unit 6 and an overvoltage determination unit 5. The switching circuit unit 6 is connected to a synchronous motor 7, converts a DC voltage from the power source into a three-phase AC voltage, drives the motor 7, and rotates the axle. Moreover, the regenerative electric power of the motor 7 is converted into direct current and supplied to the battery 1 side. The overvoltage determination unit 5 is connected to the DC power supply side terminal of the switching circuit unit 6. When a predetermined overvoltage is detected, a drive stop signal SG4 is output to the switching circuit unit 6 and the inverter 4 performs a self-protection function. In addition to the overvoltage determination unit 5, a voltage sensor 12 is provided on the DC power supply side of the switching circuit unit 6.

  A control unit 11 is connected to the DC / DC converter 8, the inverter 4 and the voltage sensor 12. The control unit 11 includes a drive stop signal SG1 output from the overvoltage determination unit 10 of the DC / DC converter 8, a drive stop signal SG4 output from the overvoltage determination unit 5 of the inverter 4, and the inverter detected by the voltage sensor 12. Receive voltage data. The control unit 11 outputs a control signal SG3 for the DC / DC converter 8 and a drive stop cancel signal SG2 for the overvoltage determination unit 10 and a control signal SG5 for the inverter 4. In addition to or instead of the drive stop cancellation signal SG2 for the overvoltage determination unit 10 of the DC / DC converter 8, a drive stop cancellation signal for the overvoltage determination unit 5 of the inverter 4 may be output.

  The vehicle power supply system of the present embodiment has been described by taking a fuel cell system as an example. However, the present invention is not limited to this, and the present invention can also be applied to a hybrid power supply system in which an internal combustion engine and a generator are combined.

<2. Operation stop and return processing>
FIG. 2 is a timing chart for explaining a return operation when the operation is stopped due to an overvoltage in the vehicle power supply system. Various signals indicate OFF at the bottom and ON at the top. During normal operation before (1) on the timeline, the high-voltage power supply voltage is in the normal range, the DC / DC converter drive stop signal SG1 and the inverter drive stop signal SG4 are OFF, and the DC / DC converter control signal SG3. The inverter control signal SG5 is ON.

  It is assumed that an abnormality has occurred in the system at (1) on the timeline and the voltage of the high voltage power supply has increased. As an example of such an abnormality, for example, when the relay of the DC / DC converter 8 is released during regenerative power generation and the battery 1 is not charged, the power supply system may be overvoltage.

  When the voltage value reaches a preset abnormal voltage (for example, 450 V) in (2) on the timeline, the switching circuit unit 9 from the overvoltage determination unit 10 of the DC / DC converter 8 and the overvoltage determination unit 5 of the inverter 4 respectively. In addition, drive stop signals SG1 and SG4 based on a self-protection function are output to the switching circuit unit 6. Then, the operations of the DC / DC converter 8 and the inverter 4 are immediately stopped. When the control unit 11 detects these drive stop signals SG1 and SG4, the control unit 11 stops the DC / DC converter control signal SG3 and the inverter control signal SG5.

  The power supply system starts a predetermined return operation after detecting the output of the drive stop signals SG1 and SG4 by the self-protection function. First, when the drive stop time has elapsed for a predetermined time (for example, 100 milliseconds), the control unit 11 checks whether or not the system abnormality that has caused the voltage rise has returned to normal. For example, in the example of the regenerative power generation described above, the abnormality is immediately resolved if the regenerative power generation is stopped. When the system abnormality has returned to normal, the control unit 11 performs return control. That is, by outputting the drive stop release signal SG2 of the DC / DC converter 8, the drive stop signal SG1 output from the overvoltage determination unit 10 is stopped, and the drive stop state is forcibly released. Thereafter, the control signal SG3 is returned at (3) on the timeline. At this time, the target voltage of the DC / DC converter 8 is set to a normal voltage upper limit, for example, 400V. As a result, the power supply voltage can be smoothly lowered.

  When the voltage falls below the abnormal level, the inverter drive stop signal SG4 output from the overvoltage determination unit 5 is also automatically restored. The control unit 11 confirms that the power supply voltage is lowered to a preset normal voltage (for example, 400 V) or less and the drive stop signal SG5 of the inverter 4 is released, and then the inverter control signal is displayed at (4) on the timeline. SG5 is returned to return to normal control. The drive stop signal SG1 of the above-described DC / DC converter has already been forcibly released, but in (4) on the timeline, the drive stop release signal SG2 for this forcible release becomes unnecessary, and this is also combined. It has been released.

  FIG. 3 is a time chart when the system abnormality is not temporary but continues. The process is the same as in FIG. 2 until the power supply voltage rises after the occurrence of an abnormality in (1) on the timeline and the control of the DC / DC converter and the inverter is stopped in (2) on the timeline.

  This figure shows a case where the system abnormality has not been recovered even after a predetermined time has elapsed after the operation of the self-protection function. In that case, the system is stopped without executing the return operation.

  For example, the control unit 11 may maintain the control stop state until the ignition switch is turned off, or may attempt to return the degree of change after a predetermined time has elapsed.

  FIG. 4 is a time chart in a case where the voltage once recovered normally after the temporary abnormality occurred but the voltage rise again during the recovery operation. The power supply voltage rises after the occurrence of an abnormality in (1) on the timeline, and the control of the DC / DC converter 8 and the inverter 4 is stopped in (2) on the timeline, as in FIG. Similarly to FIG. 2, when the drive stop state has elapsed for a predetermined period and the system has returned to normal, return control is performed and control of the DC / DC converter 8 is resumed at (3) on the timeline.

  The control unit 11 acquires power supply voltage information (voltage value or voltage change amount) from the voltage sensor 12 after a relatively short predetermined period (for example, 10 milliseconds) after the driving of the DC / DC converter is resumed. When the voltage is rising as shown in FIG. 4, the return control is stopped. That is, the control signal SG3 of the DC / DC converter is turned off, and the drive stop cancellation signal SG2 of the DC / DC converter is turned off. As a result, the DC / DC converter drive stop signal SG1 is turned ON again. In addition, the drive stop state of the inverter 4 is also left as it is, and is not returned. For example, the control unit 11 may maintain the control stop state until the ignition switch is turned off, or may retry the return for a predetermined number of times (for example, three times).

  5-7 is a flowchart which shows control of the power supply system for vehicles by embodiment of this invention. 5 is a main routine, and FIGS. 6 and 7 are subroutines called from FIG. For this control, the main routine is executed by the control unit 11 at a rate of once per second, for example. This control is managed by control state variables (0 to 2). A control state variable 0 is a normal state, 1 is a state in which return control is performed from a system stop due to an overvoltage of a high voltage power supply, and 2 is a state in which a system abnormality is confirmed and the system stop is maintained.

  In the main routine of FIG. 5, the current control state is determined. The current control state is determined based on the processing result of a subroutine (FIG. 6 or FIG. 7) executed in the past. If it is neither the control state 2 nor the control state 1 (S11: NO, S12: NO), since it is a normal state, the process proceeds to the normal control subroutine S20 of FIG.

  If it is in the control state 1 (S11: NO, S12: YES), it is determined whether or not a predetermined time (for example, 100 milliseconds) has passed after the transition to the control state 1. If it has not elapsed (S13: NO), the control signal SG3 to the DC / DC converter 8 is turned off (S14), and the control signal SG5 to the inverter 4 is also turned off (S15). Then, the drive stop cancellation signal SG2 of the DC / DC converter is also turned OFF (S16).

  When the predetermined time has elapsed since entering the control state 1 (S13: YES), the process proceeds to the return control subroutine S30 of FIG.

  If it is in the control state 2 (S11: YES), that is, if the system abnormality is confirmed, the processes of S14 to S16 are performed, and various control signals to the DC / DC converter 8 and the inverter 4 are turned off.

  Next, the normal control subroutine of FIG. 6 will be described. In this subroutine, whether the DC / DC converter drive signal SG3 is ON (S21), the DC / DC converter drive stop signal SG1 is ON (S22), or the inverter drive stop signal SG4 is ON ( S23), it is determined whether the voltage of the high-voltage power supply is in an overvoltage state (S24). When all of these are affirmed, a new abnormality occurs and the self-protection function of the DC / DC converter 8 and the inverter 4 is activated. Therefore, the control signal SG3 of the DC / DC converter is turned off (S26), the control state 1, that is, the control stop state due to overvoltage is stored in a memory (not shown) (S27), and the process returns to the main routine of FIG. The inverter control signal OFF is performed in S15 of FIG.

  If any of the above steps S21 to S24 is negative, the DC / DC converter control signal SG3 is turned ON (S28), and the control state 0, that is, the normal control state is stored in a memory (not shown) (S29), Returning to the main routine of FIG.

  Next, the return control subroutine of FIG. 7 will be described. In this subroutine, it is first determined whether or not the abnormal state of the power supply system has been resolved. If the abnormal state has not been resolved (S31: NO), this indicates that the abnormal state has not been resolved even though the DC / DC converter 8 and the inverter 4 are stopped in the control state 1 and a predetermined time has elapsed. means. Therefore, the control state 2, that is, failure confirmation is stored in a memory (not shown) (S42), and the process returns to the main routine of FIG.

  If the system returns to normal in step S31, a DC / DC converter drive stop cancellation signal SG2 is transmitted to the overvoltage determination unit 10 of the DC / DC converter (S32). As a result, it is determined whether or not the drive stop signal SG1 output from the overvoltage determination unit 10 of the DC / DC converter has stopped. If the drive stop signal SG1 is not stopped (S33: NO), the control exits the subroutine once through S41 and starts again from the beginning of this subroutine in order to wait for the drive stop signal SG1 to stop while maintaining the control state 1.

  When the drive stop signal SG1 is stopped (S33: YES), the control signal SG3 of the DC / DC converter is turned ON, and the drive of the DC / DC converter 8 is restarted (S34).

  As a result of restarting the driving of the DC / DC converter 8, when the voltage of the high-voltage power supply rises (S35: YES), it is determined that the system abnormality has not been resolved, and the control state 2, that is, the failure is confirmed. Is stored in a memory (not shown) (S42), and the process returns to the main routine of FIG.

  If the voltage does not increase even after resuming the driving of the DC / DC converter (S35: NO), it is further determined whether or not the high voltage power supply has fallen to a voltage within the normal range within a predetermined period. If the normal voltage is not reached within the predetermined period (S36: NO), the process exits the subroutine once through S41 in order to maintain the control state 1 and wait for the drive stop signal SG1 to stop, and again from the beginning of this subroutine. Try again. When the normal voltage is reached (S36: YES), it is determined whether or not the inverter drive stop signal SG4 is turned OFF. If it is not OFF (S37: NO), in order to maintain the control state 1 and wait for the drive stop signal SG1 to stop, the process exits the subroutine once through S41 and starts again from the beginning of this subroutine.

  When the inverter drive stop signal SG4 is turned OFF (S37: YES), the DC / DC converter drive stop release signal SG2 is turned OFF (S38), the inverter control signal SG5 is turned ON (S40), and the control state is set to 0. The process proceeds to the main routine of FIG.

  By repeating the above processing, the driving stop of the DC / DC converter 8 and the driving stop of the inverter 4 can be canceled at an early stage and the driving can be resumed.

  In addition, in the said embodiment, you may provide the power consumption apparatus which consumes the electric power generated with the fuel cell etc. As this load device, a fuel cell auxiliary device 2 (compressor, pump, etc.), a drive motor 7, and other vehicle electrical components can be used as a power consuming device.

1 is a schematic configuration diagram of a vehicle power supply system according to an embodiment of the present invention. It is a timing chart explaining return operation | movement when operation | movement stop by an overvoltage in the said vehicle power supply system. This is a time chart when the system abnormality is not temporary but continues. It is a time chart when a normal rise once after a temporary abnormality occurs but a voltage rise occurs again during the restoration operation. It is a flowchart which shows a main routine among control of the vehicle power supply system by embodiment of this invention. It is a flowchart which shows the subroutine of normal control among control of the vehicle power supply system by embodiment of this invention. It is a flowchart which shows the subroutine of return control among control of the power supply system for vehicles by embodiment of this invention.

Explanation of symbols

1 Battery (power storage device)
3 Fuel cell (high voltage power supply)
4 Inverter (voltage converter)
8 DC / DC converter (voltage converter)
SG1 DC / DC converter drive stop signal SG2 DC / DC converter drive stop release signal SG3 DC / DC converter control signal SG4 Inverter drive stop signal SG5 Inverter control signal

Claims (5)

A power supply system for a vehicle comprising a high voltage power supply, a power conversion device connected to the high voltage power supply, and a control device for controlling the power conversion device,
The power conversion device has a self-protection function to stop driving when the voltage of the high-voltage power supply is excessive,
The said control apparatus is a vehicle power supply system provided with the function to cancel | release the stop state by the said self-protection function of the said power converter device. In claim 1,
The control device diagnoses a system abnormality when the power conversion device is stopped by the self-protection function, and cancels the power conversion device stop state if no abnormality is detected. Power system. In claim 1 or claim 2,
Further comprising a power storage device connected to the power converter,
The said control apparatus is a power supply system for vehicles which cancels | releases the said stop state of the said power converter device. In any one of Claims 1 thru | or 3,
The control device sets the voltage control target value of the power conversion device to a maximum voltage in a normal range when releasing the stop state. In any one of Claims 1 thru | or 4,
The control device determines whether or not the voltage of the high-voltage power supply decreases after releasing the stop state of the power conversion device, and if not, restarts the driving of the power conversion device. system.

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