JP2007060789A - Inverter control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the fuel efficiency of a vehicle by making discharging energy reduced at the interruption of a system, in an inverter control device that controls the discharge of a smoothing capacitor for stabilizing the DC voltage of an inverter. <P>SOLUTION: This inverter control device is characterized, comprising the inverter 7 that converts DC power to AC power and feeds it to a drive motor 14; the smoothing capacitor 6, that is connected to the DC power side of the inverter 7 and stabilizes the DC power; and a discharge control part 24 that continues discharging, until the voltage of the smoothing capacitor 6 reaches a prescribed voltage but is not zero until the lapse of a prescribed discharge time, after the turning-off of the system of the vehicle where the inverter 7 is installed, and controls the discharge so that a discharge amount, after the lapse of the prescribed time becomes larger than the discharge amount, before the lapse of the prescribed time after the turning-off of the system, in the prescribed discharging time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inverter control device, and more particularly to an inverter control device that controls discharge of a smoothing capacitor for stabilizing a DC voltage of an inverter.

Conventionally, when turning off a vehicle system, a technique is known that ensures the safety of work by discharging electric power stored in a capacitor in an inverter until the voltage becomes zero within a specified time (for example, Patent Document 1).
JP 2004-96945 A

  As a usage of vehicles in the market, there are cases where the vehicle system is turned off at a stop or waiting for a signal, such as a route bus. In this case, since the capacitor is repeatedly charged and discharged every time the bus stops or the signal is waited for, the life of the relay used for precharging the capacitor and the capacitor is reduced. Furthermore, since the discharged electric power cannot be used for running the vehicle, the fuel consumption is reduced.

  In order to solve the above-described problems, an inverter control device according to the present invention is an inverter control device that controls an inverter that converts DC power into AC power and converts the AC power into the DC power. A smoothing capacitor that is connected in parallel to the DC power side and stabilizes the DC power, and between the time when a predetermined discharge time elapses after the system of the vehicle on which the inverter is mounted is turned off. Discharge until the voltage reaches a predetermined voltage that is not zero, and control so that the discharge amount after the predetermined time elapses more than the discharge amount before the predetermined time elapses after the system is turned off during the predetermined discharge time. And a discharge control unit for performing the operation.

  According to the inverter control device of the present invention, since the electric power stored in the smoothing capacitor is not discharged until it reaches a predetermined voltage without being discharged, the discharge energy can be reduced, thereby improving the fuel consumption of the vehicle. An inverter control device can be provided.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(First embodiment)
As shown in FIG. 1, the vehicle drive system including the inverter control device according to the first embodiment of the present invention includes an ECU 1 that controls the drive of the vehicle, a drive motor 14 that is a power source of the vehicle, and a drive A battery 13 that stores direct-current power as a power source to the motor 14, an inverter 7 that converts the direct-current power of the battery 13 into alternating-current power and supplies the alternating-current power to the drive motor 14, and a first that controls the operation of the inverter 7 And an inverter control device according to the embodiment.

  In the inverter control apparatus according to the first embodiment of the present invention, the smoothing capacitor 6 connected in parallel to the DC power side of the inverter 7 and the vehicle system in which the inverter 7 is mounted turn off the predetermined discharge. A discharge switch 24 that discharges the voltage of the smoothing capacitor 6 until a predetermined voltage that is not zero before the time elapses, and a charge switch that is turned on when charging the smoothing capacitor 6 using the energy of the battery 13 2 and the plus side switch 3 and the GND side switch 4 that are turned on when the energy of the battery 13 is energized to the stage after the smoothing capacitor 6 during system startup, and the inrush current is avoided when the charging switch 2 is turned on. The precharge resistor 5 that prevents welding of the system main relay and the DC voltage on the drive motor 14 side from the system main relay A system voltage monitor 8 to a constant, and a battery voltage monitor 9 for measuring the DC voltage of the battery 13.

  Here, the smoothing capacitor 6 is connected in parallel to the battery 13 and the inverter 7 between the battery 13 and the inverter 7, and has a function of stabilizing DC power supplied to the inverter 7.

  The discharge control unit 24 is disposed in the ECU 1 that controls the entire vehicle drive system including the inverter control device. When an abnormality occurs in the vehicle, the discharge control unit 24 is stored in the smoothing capacitor 6 until the voltage of the smoothing capacitor 6 becomes zero. Completely discharges the power.

  The battery 13 is a high-power battery connected in parallel to the DC power side of the inverter 7, and supplies DC power to the inverter 7. When the drive motor 14 performs regenerative braking, the inverter 7 converts the AC power generated by the drive motor 14 into DC power, and the battery 13 receives the DC power from the inverter 7 and stores the power.

  The plus side switch 3 and the GND side switch 4 are disposed between the battery 13 and the smoothing capacitor 6.

  The system voltage monitor 8 is connected in parallel between the inverter 7 and the smoothing capacitor 6, and measures the DC voltage on the drive motor 14 side from the system main relay. When the system main relay is off and the vehicle system is normal, the measured value of the system voltage monitor 8 becomes zero.

  The battery voltage monitor 9 is connected in parallel to the battery 13 and measures the DC voltage of the battery 13. The measured value of the battery voltage monitor 9 is always the voltage value of the battery 13.

  The charge switch 2 and the precharge resistor 5 are connected in series with each other, and are connected in parallel with the plus switch 3 between the battery 13 and the smoothing capacitor 6. The charging switch 2 is turned on only when the smoothing capacitor 6 is charged using the energy of the battery 13.

  In the inverter control device of the present embodiment described above, the “predetermined voltage” indicates a voltage value that causes no problem even if an operator touches the high voltage portion of the smoothing capacitor 6. The “high voltage portion” indicates a high voltage portion on the side where the system of the vehicle is turned off, that is, the system main relay is turned off and disconnected from the battery 13, that is, a portion where the potential of the smoothing capacitor 6 appears.

  The “predetermined discharge time” is the time from when the vehicle system is turned off until the worker can touch the high voltage portion of the smoothing capacitor 6, and is defined by Japanese laws and regulations. It is also the regulation time.

  According to Japanese laws and regulations, when the vehicle system is turned off, the voltage of the smoothing capacitor 6 is gradually reduced from the steady voltage value at startup (system voltage at startup), and the vehicle system is turned off. After that, the voltage of the smoothing capacitor 6 must be reduced to the legal regulation voltage between the regulation regulation time and the elapse of the regulation regulation time. Thus, it is obliged to ensure the safety of the worker.

  Next, vehicle control performed by the ECU 1 will be described. The ECU 1 includes an ignition (IGN) signal 10 that is transmitted only when the vehicle system is activated (ON), and a system abnormality signal 12 that is transmitted when an abnormality occurs in another system mounted on the vehicle. Receive.

  Then, after receiving the IGN signal 10, the ECU 1 detects the voltage of the battery 13 and the voltage of the smoothing capacitor 6, and the charging switch 2, plus side switch 3, and GND side switch, which are three system main relays, according to the state. 4 and the inverter 7 are controlled to convert the DC power of the battery 13 into AC power and supply it to the drive motor 14. Further, when the electric power stored in the smoothing capacitor 6 is small, the smoothing capacitor 6 is charged using the energy of the battery 13. At this time, since the inrush current having a high current density flows from the battery 13 to the smoothing capacitor 6 and the system main relay may be welded, the precharge resistor 5 is connected in series to the charge switch 2 to avoid this. ing. Further, the ECU 1 determines the welding of the system main relay based on the difference between the measured value of the system voltage monitor 8 and the measured value of the battery voltage monitor 9. Then, after the charging of the smoothing capacitor 6 is completed, the plus side switch 3 and the GND side switch 4 are turned on, and the electric power in the battery 13 is energized to the stage after the smoothing capacitor 6.

  Next, the control process when the vehicle drive system by the inverter control apparatus of this embodiment is turned off is demonstrated based on FIG. As shown in FIG. 2, first, when the ignition is turned off by an operator (for example, a vehicle driver) performing a key operation, the discharge control unit 24 of the ECU 1 stops the reception of the IGN signal 10. Is detected to be off (S201).

  Then, the discharge control unit 24 determines whether or not the entire system is normal depending on whether or not the system abnormality signal 12 is received (S202). If the entire system is not normal, the discharge process of the smoothing capacitor 6 is performed. (S203). That is, all the electric power stored in the smoothing capacitor 6 is discharged.

  On the other hand, when the entire system is normal, the discharge control unit 24 monitors whether or not a predetermined time set in advance has elapsed (S204). Here, the “predetermined time” is a time obtained by subtracting the time required for discharging the smoothing capacitor 6 from the legally prescribed time prescribed in advance by law.

  When the predetermined time has elapsed, “predetermined voltage” is set as the target discharge voltage when discharging the power of the smoothing capacitor 6 (S205), and the smoothing capacitor 6 is discharged (S206). Here, the “predetermined voltage” is a voltage value that causes no problem even if an operator touches the high voltage portion of the smoothing capacitor 6.

  When the discharge is performed in this way, the discharge control unit 24 discharges the smoothing capacitor 6 while monitoring the voltage of the smoothing capacitor 6 using the system voltage monitor 8, and the smoothing capacitor 6 is discharged during a predetermined discharge time set in advance. The discharge is completed so that the voltage becomes the “predetermined voltage” (S207), and the control process when the vehicle drive system by the inverter control device of this embodiment is turned off is terminated.

  Next, the time change of the voltage of the smoothing capacitor 6 when the above-described control process of the present embodiment is executed will be described in comparison with a conventional control method.

  As shown in FIG. 3, conventionally, when the system is turned off at time t1, discharge of the smoothing capacitor 6 is started so that the voltage becomes equal to or lower than the voltage stipulated by the regulations within the regulation period defined by the regulations of Japan. The battery was discharged and then discharged until the voltage of the smoothing capacitor 6 became zero.

  On the other hand, in the control processing of the present embodiment, when it is detected that the vehicle system is turned off due to the stop of the reception of the IGN signal 10 at time t1, the smoothing is performed after a predetermined time CL1 has elapsed. The capacitor 6 starts discharging. After time t2 when the discharge is started, the voltage of the smoothing capacitor 6 starts to decrease, and at time t3 when the regulation time stipulated by Japanese regulations elapses, the voltage of the smoothing capacitor 6 becomes “predetermined voltage”. Discharging is complete. Here, the “predetermined voltage” is a voltage (regulation prescribed voltage) prescribed by the laws and regulations of Japan corresponding to the regulation prescribed time.

  In addition, after the predetermined time has elapsed, that is, after the time t2, the discharge is not only linearly as shown in FIG. 3, but is also first gradually discharged non-linearly to lower the voltage as shown in FIG. Then, the voltage may be suddenly discharged to lower the voltage to a predetermined voltage.

  As described above, in the control processing of the present embodiment, when the voltage of the smoothing capacitor 6 reaches a predetermined voltage when the system is turned off, the discharge is stopped and the voltage of the smoothing capacitor 6 is maintained at the “predetermined voltage”. Therefore, according to the control processing of the present embodiment, the power energy Q (= C × V) accumulated in the smoothing capacitor 6 from “predetermined voltage” to zero (ground potential) is wasted compared with the conventional control method. (See FIG. 3). C represents the capacity of the smoothing capacitor 6 and V represents “predetermined voltage”.

  In addition, when the system is started again after the “predetermined discharge time” has elapsed, the conventional control method needs to charge the smoothing capacitor 6 from zero to a steady voltage value at the time of startup. In the control process of the present embodiment, the smoothing capacitor 6 may be charged from the “predetermined voltage” to the steady voltage value at startup. Therefore, in the control process of the present embodiment, the time required for charging is shorter than in the conventional control method, and the system startup time can be shortened.

  In addition, when the smoothing capacitor 6 is completely discharged at the time of system abnormality in step S203 of the flowchart of FIG. 2 described above, the vehicle system is turned off at time t1 as shown in FIG. When the determination is made, the discharge is started immediately without waiting for the elapse of the predetermined time CL1. Then, at time t3 when a predetermined discharge time elapses, the discharge is performed so that the voltage becomes equal to or lower than the predetermined voltage, and finally the discharge is performed until the voltage of the smoothing capacitor 6 becomes zero. This ensures safety when the system is abnormal.

  As described above, in the inverter control device according to the present embodiment, the voltage of the smoothing capacitor 6 is discharged to a predetermined non-zero voltage within a predetermined discharge time after the vehicle system is turned off, and the system is turned off during the predetermined discharge time. Since control is performed so that the discharge amount after the predetermined time elapses more than the discharge amount before the predetermined time elapses, the life of the smoothing capacitor 6 is improved, and the precharge time at the time of starting the system (for example, about 500 ms normally) ) Can be shortened. As a result, the system can be started up more smoothly than the conventional control method, and the charging energy required at the next start is reduced by the amount that the discharge energy of the smoothing capacitor 6 is reduced when the system is stopped. Fuel consumption can be improved.

  In particular, in the inverter control device according to the present embodiment, the discharge of the smoothing capacitor 6 is started after a predetermined time has elapsed, so that the discharge amount after the predetermined time elapses is larger than the discharge amount before the predetermined time elapses. Therefore, the life of the smoothing capacitor 6 is improved, and the precharge time at the time of starting the system can be shortened.

  Furthermore, in the inverter control apparatus of the present embodiment, the predetermined time is set to a time obtained by subtracting the time required for discharging the smoothing capacitor 6 from the legally prescribed time specified in advance by law. You can set the time.

Moreover, in the inverter control apparatus of this embodiment, when the abnormality occurs in the vehicle, the discharge of the smoothing capacitor 6 is started immediately after the vehicle system is turned off. Can be secured.
Furthermore, in the inverter control apparatus of the present embodiment, the predetermined discharge time is the time from when the vehicle system is turned off until the worker can touch the high voltage portion of the smoothing capacitor 6. Can be secured.

  Further, in the inverter control device of the present embodiment, the predetermined voltage is set to a voltage value that does not cause a problem even if the operator touches the high voltage portion of the smoothing capacitor 6, so that the safety of the operator can be ensured.

(Second Embodiment)
Next, an inverter control device according to a second embodiment of the present invention will be described. Unlike the first embodiment, the inverter control device according to the present embodiment discharges the voltage of the smoothing capacitor 6 so as to gradually decrease in a non-linear manner until a predetermined time elapses after the system is turned off. Yes. However, since the configuration of the inverter control device of the present embodiment is the same as that of the first embodiment, description thereof is omitted.

  Next, the control process when the vehicle drive system by the inverter control apparatus of this embodiment is turned off is demonstrated based on FIG. As shown in FIG. 6, when the ignition is turned off by an operator (for example, a vehicle driver) first, the discharge control unit 24 of the ECU 1 stops the ignition because the reception of the IGN signal 10 is stopped. Is detected to be in an off state (S601).

  Then, the discharge control unit 24 determines whether or not the entire system is normal depending on whether or not the system abnormality signal 12 is received (S602). If the entire system is not normal, the discharge process of the smoothing capacitor 6 is performed. (S603). That is, all the electric power stored in the smoothing capacitor 6 is discharged.

  On the other hand, if the entire system is normal, the power of the smoothing capacitor 6 is gradually discharged to nonlinearly lower the voltage of the smoothing capacitor 6 (S604). Is monitored (S605).

  Here, the “predetermined time” is a time obtained by subtracting the time required for discharging the smoothing capacitor 6 from the legally prescribed time prescribed in advance by law.

  When the predetermined time has elapsed, “predetermined voltage” is set as a target discharge voltage when discharging the power of the smoothing capacitor 6 (S606), and the smoothing capacitor 6 is discharged (S607). Here, the “predetermined voltage” is a voltage value that causes no problem even if an operator touches the high voltage portion of the smoothing capacitor 6.

  When the discharge is performed in this way, the discharge control unit 24 discharges the smoothing capacitor 6 while monitoring the voltage of the smoothing capacitor 6 using the system voltage monitor 8, and the smoothing capacitor 6 is discharged during a predetermined discharge time set in advance. The discharge is completed so that the voltage becomes the “predetermined voltage” (S608), and the control process when the vehicle drive system by the inverter control device of this embodiment is turned off is terminated.

  Next, the time change of the voltage of the smoothing capacitor 6 when the control process of the present embodiment described above is executed will be described with reference to FIG.

  In the control processing of the present embodiment, when it is detected that the vehicle system is turned off due to the stop of reception of the IGN signal 10 at time t1, the power of the smoothing capacitor 6 is gradually discharged to nonlinearly smooth the smoothing capacitor. Reduce the voltage of 6. Then, after time t2 when the predetermined time CL1 has elapsed, the power of the smoothing capacitor 6 is suddenly discharged to reduce the voltage, and at time t3 when the predetermined discharging time, which is the legal regulation time, elapses, the voltage of the smoothing capacitor 6 Becomes “predetermined voltage” and the discharge is completed.

  In addition, in the discharge after the lapse of a predetermined time, not only the linear discharge as shown in FIG. 7 but also the non-linear discharge as shown in FIG. You may make it discharge and reduce a voltage to a predetermined voltage.

  As described above, in the inverter control apparatus according to the present embodiment, discharge is performed so that the voltage of the smoothing capacitor 6 gradually decreases in a non-linear manner within a predetermined time after the vehicle system is turned off, and smoothing is performed within the predetermined discharge time. Since the voltage of the capacitor 6 is controlled so as to be lowered to a predetermined voltage that is not zero, the life of the smoothing capacitor 6 is improved, and the precharge time at the time of starting the system (for example, usually about 500 ms) can be shortened. As a result, the system can be started up more smoothly than the conventional control method, and the charging energy required at the next start is reduced by the amount that the discharge energy of the smoothing capacitor 6 is reduced when the system is stopped. Fuel consumption can be improved.

  As described above, the present invention has been described according to the first and second embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. That is, it should be understood that the present invention includes various embodiments not described herein. Therefore, the present invention is limited only by the invention specifying matters according to the scope of claims reasonable from this disclosure.

  The present invention relates to an inverter control device that controls the discharge of a smoothing capacitor that stabilizes the DC voltage of an inverter, and is particularly useful as a technique for improving the fuel efficiency of a vehicle by reducing the discharge energy when the system is stopped.

1 is a block diagram showing a vehicle drive system including an inverter control device according to a first embodiment of the present invention. It is a flowchart which shows a control process when the vehicle drive system by the inverter control apparatus which concerns on the 1st Embodiment of this invention is turned off. It is the time chart which compared the time change of the voltage of the smoothing capacitor in the inverter control apparatus which concerns on the 1st Embodiment of this invention with the conventional control method. It is a time chart which shows the time change of the voltage of the smoothing capacitor in the inverter control apparatus which concerns on the 1st Embodiment of this invention. It is a time chart which shows the time change of the voltage of the smoothing capacitor at the time of system abnormality in the inverter control apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart which shows a control process when the vehicle drive system by the inverter control apparatus which concerns on the 2nd Embodiment of this invention is turned off. It is a time chart which shows the time change of the voltage of the smoothing capacitor in the inverter control apparatus which concerns on the 2nd Embodiment of this invention. It is a time chart which shows the time change of the voltage of the smoothing capacitor in the inverter control apparatus which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

1 ... ECU
2 ... Charge switch 3 ... Plus side switch 4 ... GND side switch 5 ... Precharge resistor 6 ... Smoothing capacitor 7 ... Inverter 8 ... System voltage monitor 9 ... Battery voltage monitor 10 ... IGN signal 12 ... System abnormal signal 13 ... Battery 14 ... Driving motor 24... Discharge controller

Claims (7)

An inverter control device that controls an inverter that converts DC power into AC power and converts the AC power into the DC power,
A smoothing capacitor connected in parallel to the DC power side of the inverter and stabilizing the DC power;
The smoothing capacitor voltage is discharged until a predetermined voltage that is not zero after the system of the vehicle on which the inverter is mounted is turned off until a predetermined discharge time elapses. An inverter control device, comprising: a discharge control unit that controls the discharge amount after the predetermined time has elapsed to be greater than the discharge amount before the predetermined time has elapsed since the system was turned off.   The inverter control device according to claim 1, wherein the discharge controller starts discharging the smoothing capacitor after the predetermined time has elapsed.   The inverter control device according to claim 1, wherein the discharge control unit discharges the smoothing capacitor so that the voltage of the smoothing capacitor gradually decreases in a non-linear manner during the predetermined time.   4. The method according to claim 1, wherein the predetermined time is a time obtained by subtracting a time required for discharging the smoothing capacitor from a legally prescribed time that is prescribed in advance. Inverter control device.   5. The discharge controller according to claim 1, wherein, when an abnormality occurs in the vehicle, the discharge of the smoothing capacitor is started immediately after the vehicle system is turned off. The inverter control device described in 1.   6. The predetermined discharge time is a time from when the vehicle system is turned off until an operator can touch the high voltage portion of the smoothing capacitor. The inverter control device according to any one of the above.   The inverter control device according to any one of claims 1 to 6, wherein the predetermined voltage is a voltage value that causes no problem even if an operator touches a high voltage portion of the smoothing capacitor.

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