JP4934959B2 - Inverter control device - Google Patents

Description

  The present invention relates to an inverter control device, and more particularly to an inverter control device that controls charging / discharging of a smoothing capacitor that stabilizes a DC voltage of an inverter.

2. Description of the Related Art Conventionally, when turning off a vehicle system, a technique for ensuring work safety by discharging electric power stored in a capacitor in an inverter until the voltage becomes zero within a specified time (for example, patents) is known. Reference 1).
JP 2004-96945 A

For example, when a user or an operator removes a power supply terminal or the voltage drops due to self-discharge of the power supply, the power supply voltage supplied to the inverter control apparatus cannot be activated or the inverter control The voltage may be lower than the voltage at which the function of the device cannot be guaranteed. In such a case, since the inverter control device cannot discharge the energy stored in the smoothing capacitor, the safety of the inverter control device decreases.

A feature of the present invention is that a smoothing capacitor connected in parallel to a DC power side of an inverter that mutually converts DC power and AC power for the purpose of stabilizing DC power, and a vehicle system equipped with the inverter Whether the power stored in the smoothing capacitor is discharged until the predetermined time elapses after the power is turned off until the voltage of the smoothing capacitor reaches a predetermined voltage that is not zero , and whether the power supply voltage is supplied to the inverter control device When the discharge control unit determines that the power supply voltage is not supplied to the inverter control device and the discharge control unit determines whether or not , the power stored in the smoothing capacitor is discharged until the voltage of the smoothing capacitor becomes zero. A gist of the invention is an inverter control device including a discharge circuit.

According to the present invention, when the power supply voltage supplied to the inverter control device is equal to or lower than the voltage value at which the inverter control device cannot be activated due to the power supply voltage not being supplied to the inverter control device, the discharge circuit is connected to the smoothing capacitor. By discharging the electric power stored in the smoothing capacitor until the voltage becomes zero, the energy stored in the smoothing capacitor can be surely discharged, so that the safety of the inverter control device is improved.

  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 a drive motor 14 that is a power source of the vehicle, and a direct current that is a power source to the drive motor 14. A battery 13 that stores electric power, an inverter 7 that converts the DC power of the battery 13 into AC power and supplies it to the drive motor 14, and an inverter control device according to the first embodiment that controls the operation of the inverter 7. With.

  The inverter control device according to the first embodiment of the present invention has a predetermined time after the system of the smoothing capacitor 6 connected in parallel to the DC power side of the inverter 7 and the vehicle on which the inverter 7 is mounted is turned off. In this case, the discharge control unit 24 discharges the electric power stored in the smoothing capacitor 6 until the voltage of the smoothing capacitor 6 reaches a predetermined voltage that is not zero before the lapse of time, and the vehicle system is restarted within a predetermined time. Thus, only when the difference between the voltage of the battery 13 and the voltage of the smoothing capacitor 6 is larger than a predetermined difference, the charge control unit 25 that charges the smoothing capacitor 6 using the power stored in the battery 13, The charging switch 2 that is turned on when the smoothing capacitor 6 is charged using energy, and the energy of the battery 13 during the system start-up A positive side switch 3 and a GND side switch 4 that are turned on when energizing the stage, a precharge resistor 5 that avoids an inrush current when the charging switch 2 is turned on and prevents welding of the system main relay, and a system A system voltage monitor 8 that measures the DC voltage on the drive motor 14 side of the main relay and a battery voltage monitor 9 that measures the DC voltage of the battery 13 are provided.

  Here, 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 time” indicates the time from when the vehicle system is turned off until the worker can touch the high voltage portion of the smoothing capacitor 6. Further, the “predetermined difference” indicates a potential difference in which a current value flowing from the battery 13 to the smoothing capacitor 6 when the vehicle system is restarted is within an allowable range. The specification of the battery 13 and the smoothing capacitor 6, particularly the battery 13 and It is determined by the voltage, capacitance and temperature characteristics of the smoothing capacitor 6.

  When the abnormality occurs in the vehicle and when the high-power portion is disconnected from the vehicle system, that is, when the ILK signal 11 is in the ON state, the discharge control unit 24 is configured to smooth the smoothing capacitor 6 until the voltage of the smoothing capacitor 6 becomes zero. The power stored in is completely discharged. The charge control unit 25 is charged in the battery 13 if the difference between the voltage of the battery 13 and the voltage of the smoothing capacitor 6 is equal to or less than the predetermined difference even when the vehicle system is restarted within a predetermined time. The smoothing capacitor 6 is not charged using electric 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 smoothing capacitor 6 is connected in parallel to the battery 13 and the inverter 7 between the battery 13 and the inverter 7. 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. The battery voltage monitor 9 is connected to the battery 13 in parallel. The charge switch 2 and the precharge resistor 5 are connected in series to each other, and are connected in parallel to the plus side switch 3 between the battery 13 and the smoothing capacitor 6. The smoothing capacitor 6 has a function of stabilizing DC power supplied to the inverter.

  The discharge control unit 24 and the charge control unit 25 are arranged in the ECU 1 that controls the entire vehicle drive system including the inverter control device. The ECU 1 generates an ignition (IGN) signal 10 that is transmitted only when the vehicle system is activated (turned on), and when the operator performs work on the high-voltage system in the vehicle drive system or when the high-voltage system is abnormal. An interlock (ILK) signal 11 transmitted at a certain time and a system abnormality signal 12 transmitted when an abnormality occurs in another system mounted on the vehicle are received.

  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 according to the state, the charge switch 2, the plus side switch 3, and the GND side switch 4 as three system main relays. And inverter 7 are controlled to convert the DC power of battery 13 into AC power and supply it to drive motor 14.

  When the power stored in the smoothing capacitor 6 is small, the smoothing capacitor 6 is charged using the energy of the battery 13. The charging switch 2 is turned on only when the smoothing capacitor 6 is charged using the energy of the battery 13. When the electric power stored in the smoothing capacitor 6 is small, an 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. Therefore, the precharge resistor is connected in series with the charging switch 2. This is avoided by connecting 5. 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.

  The system voltage monitor 8 measures the DC voltage on the drive motor 14 side relative to the system main relay, and when the system main relay is off and the vehicle system is normal, the measured value of the system voltage monitor 8 is zero. It becomes. The battery voltage monitor 9 measures the DC voltage of the battery 13, and the measured value of the battery voltage monitor 9 is always the voltage value of the battery 13. 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.

  Next, a processing procedure of the inverter control device when the vehicle drive system of FIG. 1 is turned off and restarted will be described with reference to FIG.

  (A) First, in step S11, when an operator (for example, a vehicle driver) performs a key operation, the discharge control unit 24 of the ECU 1 stops receiving the IGN signal 10, that is, the ignition is turned off. Is detected. In step S12, the discharge control unit 24 determines whether the vehicle system is normal, or whether the ILK signal 11 or the system abnormality signal 12 is received, and confirms that the entire system is normal. Check. The ILK signal 11 is detected because the system is not normal when the ILK signal 11 is detected regardless of the operator's intention.

  (B) If the entire system is not normal (NO in step S12), the process proceeds to step S21, and the discharge control unit 24 performs the discharge process of the smoothing capacitor 6 as in the conventional case. That is, all the electric power stored in the smoothing capacitor 6 is discharged. On the other hand, if the entire system is normal (YES in step S12), the process proceeds to step S13, where the discharge controller 24 turns off the vehicle system based on whether or not the ILK signal 11 is received. Determine if you need to work. That is, when the ILK signal 11 is detected, it is determined that the operator needs to work on the high voltage system in the vehicle drive system or the high voltage system is abnormal.

  (C) When the operator does not need to work (NO in step S13), the process proceeds to step S21, and the discharge control unit 24 performs the discharge process of the smoothing capacitor 6 as in the conventional case. On the other hand, when the operator needs to work (YES in step S13), the process proceeds to step S14, and the discharge control unit 24 sets a target discharge voltage as a “predetermined voltage” when discharging the power of the smoothing capacitor 6. In step S15, the smoothing capacitor 6 is discharged.

  (D) In step S16, the charging control unit 25 of the ECU 1 monitors whether or not the IGN signal 10 is received again during discharging of the smoothing capacitor 6 (step S18). When the IGN signal 10 is received again within the “predetermined time” after starting the discharge of the smoothing capacitor 6 (YES in step S16), the process proceeds to step S17, where the charge control unit 25 determines the voltage of the battery 13 and the smoothing capacitor 6 It is determined whether or not the difference from the voltage is larger than the “predetermined difference” α. On the other hand, when the IGN signal 10 is not received during discharge of the smoothing capacitor 6 (step S18) (YES in step S18), the discharge control unit 24 uses the system voltage monitor 8 to monitor the voltage of the smoothing capacitor 6 while smoothing. The capacitor 6 is discharged, and when the voltage of the smoothing capacitor 6 reaches the “predetermined voltage”, the discharge is completed and the process ends.

  (E) When the difference between the voltage of the battery 13 and the voltage of the smoothing capacitor 6 is equal to or greater than the “predetermined difference” α (NO in step S17), the process proceeds to step S20, and the charge control unit 25 is charged in the battery 13. The smoothing capacitor 6 is charged (precharged) using the power and the precharge resistor 5. When the difference between the voltage of the battery 13 and the voltage of the smoothing capacitor 6 is smaller than the “predetermined difference” α (YES in step S17), the process proceeds to step S19, and the charge control unit 25 does not perform precharge, Is not charged, the smoothing capacitor 6 is not charged.

  With reference to FIG. 3, the time change of the voltage of the smoothing capacitor in the system state in the processing procedure according to the flowchart shown in FIG. 2 and the prior art and the embodiment of the present invention will be described.

  It is detected that the vehicle system is turned off by stopping the reception of the IGN signal 10. At the same time, the discharge of the smoothing capacitor 6 in the prior art and the embodiments of the present invention (hereinafter abbreviated as “prior art” and “embodiment”) is started, and the voltage of the smoothing capacitor 6 starts to decrease. When the “predetermined time” has elapsed since the discharge of the smoothing capacitor 6 has started, the voltage of the smoothing capacitor 6 of the related art and the embodiment becomes the “predetermined voltage”. Here, “predetermined time” is the time defined by Japanese laws and regulations (regulatory prescribed time), and “predetermined voltage” corresponds to the voltage prescribed by Japanese laws and regulations (regulatory provisions). Voltage). In the prior art, even after the “predetermined time” has elapsed, the smoothing capacitor 6 continues to be discharged, and the voltage of the smoothing capacitor 6 drops below the “predetermined voltage” to zero. On the other hand, in the prior art, after the “predetermined time” has elapsed, the discharge of the smoothing capacitor 6 is stopped, and the voltage of the smoothing capacitor 6 is maintained at the “predetermined voltage”. Therefore, according to the embodiment, power energy Q (= C × V) accumulated in the smoothing capacitor 6 from “predetermined voltage” to zero (ground potential) is not wasted as compared with the conventional technique. C represents the capacity of the smoothing capacitor 6 and V represents “predetermined voltage”.

  Further, when the system is started after the “predetermined time” has elapsed, in the related art, it is necessary to charge the smoothing capacitor 6 from zero to a steady voltage value at the time of starting. It is sufficient to charge from the “predetermined voltage” to the steady voltage value at the time of start-up. Therefore, the time required for charging in the embodiment is shorter than in the prior art, and the system startup time can be shortened.

  According to the above-mentioned regulations, as shown in FIG. 4, the voltage of the smoothing capacitor 6 gradually decreases from the steady voltage value at startup (system voltage at startup) after the vehicle system is turned off. It is obliged to ensure the safety of the operator by reducing the voltage of the smoothing capacitor 6 to the legal regulation voltage by the legal regulation time after the system is turned off.

  As described above, according to the first embodiment of the present invention, the voltage of the smoothing capacitor 6 is not zero within a “predetermined time” after the discharge control unit 24 turns off the vehicle system. Since the life of the smoothing capacitor 6 is improved by discharging to a short time and the precharge time at the time of starting the system (for example, usually about 500 ms) can be shortened, the system can be started up more smoothly than in the prior art. I can do it. Further, since the discharge energy of the smoothing capacitor 6 is reduced, the charging energy required at the next start is reduced, and the fuel efficiency is improved.

  Further, the discharge control unit 24 smoothes until the voltage of the smoothing capacitor 6 becomes zero when an abnormality occurs in the vehicle and when a high-power part is disconnected from the vehicle system, that is, when the ILK signal 11 is in an ON state. When the power stored in the capacitor 6 is completely discharged, the smoothing capacitor 6 can be surely discharged when there is a possibility that the operator may work on the high-power facility.

  Furthermore, even when the charging control unit 25 restarts the vehicle system within a predetermined time, if the difference between the voltage of the battery 13 and the voltage of the smoothing capacitor 6 is equal to or less than the predetermined difference, the smoothing capacitor 6 is turned on. By not charging, the energy loss due to the precharge resistor 5 and the frequency of use of the precharge relay are reduced, and the life of the entire apparatus is improved.

  In addition, when the battery capacity of the battery 13 is large, the stored energy is high, so that the battery voltage of the battery 13 does not decrease even if the current flows out. To reduce the “predetermined difference”, the voltage of the smoothing capacitor 6 is increased. There is a need. In addition, when the vehicle system is restarted immediately after being turned off, it is difficult to consider a situation in which the temperature difference between the battery 13 and the smoothing capacitor 6 increases. However, since both have different temperature characteristics, the “predetermined difference” is determined. In doing so, the temperature characteristics of both cannot be ignored.

(Second Embodiment)
As shown in FIG. 5A, the vehicle drive system including the inverter control apparatus according to the second embodiment of the present invention includes a drive motor 14 that is a power source of the vehicle, A battery 13 that stores direct-current power as a power source in the motor 14, an inverter 7 that converts the direct-current power of the battery 13 into AC power and supplies the alternating-current power to the drive motor 14, and a second that controls the operation of the inverter 7. And an inverter control device according to the embodiment.

  The inverter control apparatus according to the second embodiment of the present invention has a predetermined time after the smoothing capacitor 6 connected in parallel to the DC power side of the inverter 7 and the system of the vehicle on which the inverter 7 is mounted are turned off. In this case, the discharge control unit 24 discharges the electric power stored in the smoothing capacitor 6 until the voltage of the smoothing capacitor 6 reaches a predetermined voltage that is not zero before the lapse of time, and the vehicle system is restarted within a predetermined time. Thus, only when the difference between the voltage of the battery 13 and the voltage of the smoothing capacitor 6 is larger than a predetermined difference, the charge control unit 25 that charges the smoothing capacitor 6 using the power stored in the battery 13, The charging switch 2 that is turned on when the smoothing capacitor 6 is charged using energy, and the energy of the battery 13 during the system start-up A positive side switch 3 and a GND side switch 4 that are turned on when energizing the stage, a precharge resistor 5 that avoids an inrush current when the charging switch 2 is turned on and prevents welding of the system main relay, and a system A system voltage monitor 8 that measures the DC voltage on the drive motor 14 side of the main relay, a battery voltage monitor 9 that measures the DC voltage of the battery 13, and a temperature sensor 15 that estimates the internal temperature of the smoothing capacitor 6 are provided. . Compared to FIG. 1, the temperature sensor 15 is further provided.

  The discharge control unit 24 and the charge control unit 25 are arranged in the ECU 1 that controls the entire vehicle drive system including the inverter control device. The ECU 1 generates an ignition (IGN) signal 10 that is transmitted only when the vehicle system is activated (turned on), and when the operator performs work on the high-voltage system in the vehicle drive system or when the high-voltage system is abnormal. An interlock (ILK) signal 11 transmitted at a certain time and a system abnormality signal 12 transmitted when an abnormality occurs in another system mounted on the vehicle are received.

  Note that “predetermined voltage”, “predetermined time”, and “predetermined difference” are the same as those in the first embodiment, and a description thereof will be omitted.

  As shown in FIG. 5 (b), the charging control unit 25 in FIG. 5 (a) includes a leaving time calculating unit 26 for calculating a leaving time until the vehicle system is turned off and restarted, and a leaving time. A potential difference state determination unit 27 that determines whether or not the difference between the voltage of the battery 13 and the voltage of the smoothing capacitor 6 is larger than the “predetermined difference” based on the leaving time calculated by the calculation unit 26. That is, the potential difference state determination unit 27 estimates the voltage of the smoothing capacitor 6 from the self-discharge characteristics of the smoothing capacitor 6.

  In addition, the charge control unit 25 has a function of storing information on self-discharge characteristics indicating a relationship between an elapsed time after the vehicle system is turned off and a residual voltage of the smoothing capacitor 6. For example, as shown in FIG. 7, in the self-discharge characteristic of the smoothing capacitor 6, the remaining voltage of the smoothing capacitor 6 decreases as the standing time increases. In this case, the potential difference state determination unit 27 utilizes the self-discharge characteristic in which the voltage of the smoothing capacitor 6 decreases as the standing time increases. Note that it is desirable that the self-discharge characteristics of the smoothing capacitor 6 take into account the temperature and deterioration of the smoothing capacitor 6. For example, as shown in FIG. 7, the potential difference state determination unit 27 sets the leaving time longer as the temperature of the smoothing capacitor 6 becomes higher than the normal temperature, and sets the leaving time shorter as the smoothing capacitor 6 deteriorates. It doesn't matter. This is because when the temperature is lowered, the capacity of the smoothing capacitor 6 is lowered, and the voltage drop rate is higher than the normal temperature even if the self-discharge is small. Moreover, it is considered that the deterioration is the same, and the temperature and the deterioration are independent from each other.

  Next, a processing procedure of the inverter control device when the vehicle drive system of FIG. 5 is turned off and restarted will be described with reference to FIG.

  (A) First, in this process, when an operator (for example, a vehicle driver) performs a key operation, the discharge control unit 24 of the ECU 1 stops receiving the IGN signal 10, that is, the ignition is turned off. It is started by detecting that. In step S31, the ECU 1 determines whether or not the vehicle system has detected diagnostic information at the previous activation. If the diagnosis information is not detected (YES in step S31), the process proceeds to step S32. If the diagnosis information is detected (NO in step S31), the process proceeds to step S40.

  (B) In step S32, the leaving time calculation unit 26 starts a timer in order to calculate the leaving time until the vehicle system is turned off and restarted. In step S33, the leaving time calculation unit 26 monitors whether or not the IGN signal 10 is received again. The process does not proceed to the next stage until the IGN signal 10 is received. During this time, the timer count continues.

  (C) When the IGN signal 10 is received again and the system is restarted (YES in step S33), the process proceeds to step S34, and the internal temperature of the smoothing capacitor 6 is estimated using the temperature sensor 15. This is because it is necessary to consider the self-discharge characteristics when estimating the voltage of the smoothing capacitor 6 when the system is restarted. In step S35, the leaving time calculation unit 26 stops the timer.

  (D) In step S36, the potential difference state determination unit 27 determines the leaving time calculated by the leaving time calculation unit 26, the internal temperature of the smoothing capacitor 6 estimated by the temperature sensor 15, and the smoothing capacitor 6 calculated inside the ECU 1. The voltage of the smoothing capacitor 6 is estimated using the degree of deterioration of For example, the voltage of the smoothing capacitor 6 is calculated by multiplying the “self-discharge characteristic reference value” obtained from the self-discharge characteristic shown in FIG. 7, “temperature coefficient”, and “deterioration coefficient”.

  (E) In step S37, the battery voltage monitor 9 is used to measure the voltage (Vb) of the battery 13. In step S38, the potential difference state determination unit 27 determines whether or not the difference between the voltage of the battery 13 and the estimated voltage of the smoothing capacitor 6 is greater than the “predetermined difference” α. When the difference between the voltage of the battery 13 and the estimated voltage of the smoothing capacitor 6 is equal to or greater than the “predetermined difference” α (NO in step S38), the process proceeds to step S42. The smoothing capacitor 6 is charged (precharged) using the precharge resistor 5. When the difference between the voltage of the battery 13 and the estimated voltage of the smoothing capacitor 6 is smaller than the “predetermined difference” α (YES in step S17), the process proceeds to step S39, and the charge control unit 25 does not perform precharge and the system main The smoothing capacitor 6 is not charged because there is no possibility of the relay welding.

  (F) On the other hand, when a diagnosis is detected in step S31, the process proceeds to step S40, and the voltage of the smoothing capacitor 6 is discharged to zero volts without being kept at the “predetermined voltage”. This is because, if energy remains in the smoothing capacitor 6, consideration work for ensuring the safety of the worker is necessary, and as a result, workability deteriorates. In step S41, the leaving time calculation unit 26 monitors whether or not the IGN signal 10 is received again. The process does not proceed to the next stage until the IGN signal 10 is received. After receiving the IGN signal 10, the process proceeds to step S42.

  As shown in FIG. 8 (a), when the voltage difference between the battery 13 and the smoothing capacitor 6 is smaller than the predetermined difference α, the precharge is unnecessary, so the charge switch 2 is not turned on, and the positive switch 3 Is turned on and the smoothing capacitor 6 is charged. On the other hand, as shown in FIG. 8B, when the voltage difference between the battery 13 and the smoothing capacitor 6 is equal to or larger than the predetermined difference α, precharge is necessary. Turned on and the smoothing capacitor 6 is charged.

  The second embodiment is particularly effective when the voltage of the battery 13 is relatively low. This is because the voltage of the smoothing capacitor 6 after the vehicle system is turned off is a voltage value stipulated by the law at the maximum, and the precharge is not required only when the difference between the law stipulated voltage and the voltage of the battery 13 is small. Because. For example, when the voltage Vc of the smoothing capacitor 6 is 60V and the potential difference α at which the system main relay is not welded is 50V, it is not applicable to a system in which the voltage Vb of the battery 13 is 400V. This is applicable to a system having a voltage Vb of 100V.

  As described above, according to the second embodiment, the necessity of precharging is determined by taking into account the self-discharge characteristic of the smoothing capacitor 6 whose voltage decreases after the system is turned off. Welding of the system main relay can be avoided reliably. If the self-discharge characteristic of the smoothing capacitor 6 is not taken into consideration, the potential difference between the battery 13 and the smoothing capacitor 6 is evaluated to be smaller than the actual value, and the system main relay may be welded.

  By taking the self-discharge characteristic of the smoothing capacitor 6 into consideration, it is not necessary to measure the voltage of the smoothing capacitor 6 when the system is restarted, and the start-up time can be shortened.

  By taking into account the temperature and the degree of deterioration that affect the self-discharge characteristics of the smoothing capacitor 6, the voltage of the smoothing capacitor 6 can be estimated with higher accuracy.

  Estimating the voltage of the smoothing capacitor 6 with higher accuracy by setting the standing time longer as the temperature of the smoothing capacitor 6 becomes higher than normal temperature and setting the standing time shorter as the deterioration of the smoothing capacitor 6 progresses. I can do it.

  When the discharge control unit 24 is discharging the electric power stored in the smoothing capacitor 6 when the vehicle system is turned off, the charge control unit 25 can charge the smoothing capacitor 6 regardless of the leaving time. desirable.

  Instead of the temperature sensor 15, the internal temperature of the smoothing capacitor 6 may be estimated using an atmosphere temperature monitor that measures the temperature of the atmosphere in the vehicle system.

  The degree of deterioration of the smoothing capacitor 6 may be calculated on the basis of the integration time from the initial startup of the system, but may be calculated by applying the deterioration over time based on the operating temperature condition or frequency. In this case, a table showing the relationship between the integration time and the deterioration is set and referred to.

(Third embodiment)
As shown in FIG. 9, the vehicle drive system including the inverter control device according to the third embodiment of the present invention includes a drive motor 14 as a power source of the vehicle, and a drive motor 14 as in FIG. A battery 13 that stores DC power as a power source, an inverter 7 that converts the DC power of the battery 13 into AC power and supplies it to the drive motor 14, and a third embodiment for controlling the above-described operation of the inverter 7. And an inverter control device according to the embodiment.

  The inverter control device according to the third embodiment of the present invention has a predetermined time after the smoothing capacitor 6 connected in parallel to the DC power side of the inverter 7 and the system of the vehicle on which the inverter 7 is mounted are turned off. When the smoothing capacitor 6 is charged using the energy of the battery 13 and the discharge control unit 24 that discharges the electric power stored in the smoothing capacitor 6 until the voltage of the smoothing capacitor 6 reaches a predetermined voltage that is not zero until the time has elapsed. The charging switch 2 that is turned on, 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 charging switch 2 is turned on Precharge resistor 5 that prevents inrush current and prevents welding of the system main relay, and for driving than the system main relay Includes a system voltage monitor 8 for measuring the DC voltage over motor 14 side, the battery voltage monitor 9 for measuring the DC voltage of the battery 13, and a discharge circuit 16 connected in parallel with the smoothing capacitor 6. Compared to FIG. 1, it is different in that a discharge circuit 16 is further provided.

  The discharge controller 24 is disposed in the ECU 1 that controls the entire vehicle drive system including the inverter control device. The ECU 1 generates an ignition (IGN) signal 10 that is transmitted only when the vehicle system is activated (turned on), and when the operator performs work on the high-voltage system in the vehicle drive system or when the high-voltage system is abnormal. An interlock (ILK) signal 11 transmitted at a certain time and a system abnormality signal 12 transmitted when an abnormality occurs in another system mounted on the vehicle are received.

  The discharge circuit 16 forcibly discharges the electric power stored in the smoothing capacitor 6 until the voltage of the smoothing capacitor 6 becomes zero when the power supply voltage supplied to the inverter control device is equal to or lower than the second predetermined voltage. . Further, even when the vehicle system is off, the discharge circuit 16 causes the voltage of the smoothing capacitor 6 to be zero if the power supply voltage supplied to the inverter control device is equal to or lower than the second predetermined voltage. It is desirable to discharge the electric power stored in the smoothing capacitor 6 until. Here, the “second predetermined voltage” indicates a voltage value at which the inverter control device cannot be started or the function of the inverter control device cannot be guaranteed.

  Note that “predetermined voltage” and “predetermined time” are the same as those in the first embodiment, and a description thereof will be omitted.

  As shown in FIG. 10, the discharge circuit of FIG. 9 includes a normally closed type discharge switch 22 that is normally de-energized and a current that flows from the smoothing capacitor 6 when the discharge switch 22 is energized. And a discharge resistor 23 that consumes the energy stored in the battery. The ECU 1 also includes a power source 20 that supplies a voltage of 12 V to the ECU 1 and a backup power source 21.

  When a 12 V power supply voltage is supplied to the ECU 1, power is supplied from the power supply 20 to the discharge switch 22 and the discharge switch 22 is excited, whereby the discharge switch 22 is de-energized, and the energy of the smoothing capacitor 6 becomes the discharge resistance. 23 is not energized. On the other hand, when the 12V power supply voltage is not supplied to the ECU 1, no power is supplied from the power supply 20 to the discharge switch 22, so that the discharge switch 22 is not excited, the discharge switch 22 is energized, and the energy of the smoothing capacitor 6 is the discharge resistance 23. Is energized. The backup power source 21 has a capacity capable of supplying an exciting current to the discharge switch 22 during the instantaneous interruption time. The discharge switch 22 is not excited when the 12V power supply voltage drops below a specified value. Further, the discharge resistor 23 has a resistance value such that the discharge switch 22 does not melt even when the smoothing capacitor 6 is energized from the state where the regulation voltage is stored.

  Next, a processing procedure of the inverter control device when the vehicle drive system of FIG. 9 is off will be described with reference to FIG.

  (A) First, in step S51, when an operator (for example, a vehicle driver) performs a key operation, the discharge control unit 24 of the ECU 1 stops receiving the IGN signal 10, that is, the ignition is turned off. It is always determined whether or not the system has been turned off by detecting this. As a result, the excitation to the discharge switch 22 can be stopped while the system is activated, and the power consumption can be reduced. If the system is turned off (YES in step S51), the process proceeds to step S52. If the system is not turned off (NO in step S51), the process proceeds to step S56.

  (B) In step S52, the discharge control unit 24 determines whether or not a non-zero voltage exists in the smoothing capacitor 6 using the system voltage monitor 8. This is because when the system abnormal signal 12 is received while the system is activated, the processing procedure is to discharge the energy in the smoothing capacitor 6 when the system is turned off. If a voltage exists (YES in step S52), the process proceeds to step S53, and if no voltage exists (NO in step S52), the process proceeds to step S56.

  (C) In step S53, the discharge control unit 24 monitors that the 12V power supply voltage in the ECU 1 decreases. For example, the user or the operator monitors the voltage drop due to the 12V power supply (battery) terminal being disconnected and the self-discharge of the 12V power supply. It will not proceed to the next stage until the 12V supply voltage drops.

  (D) When the 12V power supply voltage drops (YES in step S53), the process proceeds to step S54, and it is monitored that the state in which the 12V power supply voltage has dropped continues for a specified time (voltage drop time). It does not proceed to the next stage until the state in which the 12V power supply voltage is lowered continues for a specified time. This is because it is determined that the 12V power supply voltage does not decrease if the 12V power supply voltage decreases instantaneously. The voltage drop time is an instantaneous interruption determination time guaranteed by the system, and the instantaneous interruption determination time needs to have a backup power source 21 so that the discharge switch 22 of FIG. 10 can be excited. After the state in which the 12V power supply voltage is lowered continues for a specified time, the process proceeds to step S55, the excitation to the discharge switch 22 is stopped, and the energy of the smoothing capacitor 6 is supplied to the discharge resistor 23 to be discharged.

  (E) On the other hand, if the system is not turned off (NO in step S51), the process proceeds to step S56, it is determined that the control according to the third embodiment described above is not applied, and excitation to the discharge switch 22 is stopped. To reduce power consumption.

  As described above, when the 12V power supply voltage supplied to the inverter control device by the discharge circuit 16 is equal to or lower than the second predetermined voltage, the electric power stored in the smoothing capacitor 6 until the voltage of the smoothing capacitor 6 becomes zero. Can discharge the energy accumulated in the smoothing capacitor 6 reliably even when the user or the operator removes the 12V power supply (battery) terminal or the voltage drops due to the self-discharge of the 12V power supply. The safety of the control device is improved.

  As shown in FIG. 12A, when the system is turned off, the voltage of the smoothing capacitor 6 decreases due to discharge. When no decrease in the 12V power supply voltage in the ECU 1 is observed, excitation to the discharge switch 22 is continued and the voltage of the smoothing capacitor 6 is maintained at a predetermined voltage that is not zero. As shown in FIG. 12B, when the system is turned off, first, the voltage of the smoothing capacitor 6 is reduced to a predetermined voltage by discharging. Thereafter, when a decrease in the 12V power supply voltage in the ECU 1 is observed, the excitation to the discharge switch 22 is stopped, the energy of the smoothing capacitor 6 is completely discharged, and the voltage becomes zero. As shown in FIG. 12C, when an abnormality occurs in the system when the system is on, the voltage of the smoothing capacitor 6 is completely discharged and the voltage becomes zero at the same time when the system is turned off. .

  As described above, the voltage that guarantees the function of the inverter control device by selecting the voltage value at which the inverter control device cannot be started or the function of the inverter control device cannot be guaranteed as the “second predetermined voltage”. Within the range, the energy stored in the smoothing capacitor 6 can be reliably managed.

  The discharge circuit 16 can avoid a situation in which the energy stored in the smoothing capacitor 6 cannot be discharged because there is no system power supply by responding even when the vehicle system is off.

  The discharge circuit 16 includes a normally closed type discharge switch that is normally de-energized, so that even when a user or an operator removes the 12V power supply (battery) terminal or the voltage drops due to self-discharge of the 12V power supply. Since the energy stored in the smoothing capacitor 6 can be surely discharged, it is possible to cope with the system being in the off state.

  As described above, the present invention has been described according to the first to third 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.

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 the process sequence of the inverter control apparatus at the time of OFF of the vehicle drive system of FIG. 1, and restarting. It is a time chart which shows the time change of the voltage of the smoothing capacitor in the system state in the processing procedure according to the flowchart shown in FIG. 2, and a prior art and embodiment of this invention. It is a graph which shows a time change when the voltage of a smoothing capacitor falls by discharge after a vehicle system is turned off. FIG. 5 (a) is a block diagram showing a vehicle drive system including an inverter control device according to the second embodiment of the present invention, and FIG. 5 (b) is a detail of the charge control unit of FIG. 5 (a). It is a block diagram which shows a structure. It is a flowchart which shows the process sequence of the inverter control apparatus at the time of OFF of the vehicle drive system of FIG. 5, and restarting. It is a graph which shows an example of the self-discharge characteristic of a smoothing capacitor. FIG. 8A is a graph showing the voltage difference between the battery and the smoothing capacitor, the voltage of the smoothing capacitor, and the change over time of the switch opening and closing when precharging is unnecessary, and FIG. 8B needs precharging. It is a graph which shows the time difference of the voltage difference of a battery and a smoothing capacitor, the voltage of a smoothing capacitor, and switch opening and closing at that time. It is a block diagram which shows the vehicle drive system containing the inverter control apparatus concerning the 3rd Embodiment of this invention. It is a block diagram which shows the detailed structure of the discharge circuit of FIG. 10 is a flowchart showing a processing procedure of the inverter control device when the vehicle drive system of FIG. 9 is off. 12A is a graph showing a normal system state in which the 12V power supply voltage does not decrease, the 12V power supply voltage, the voltage of the smoothing capacitor, and the discharge switch over time. FIG. 12B is a graph showing the 12V power supply voltage decreasing. FIG. 12C is a graph showing a system state when discharge is required, a 12V power supply voltage, a voltage of a smoothing capacitor, and a time change of a discharge switch. FIG. It is a graph which shows a time change of a voltage and a discharge switch.

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 11 ... ILK signal 12 ... System abnormality signal 13 DESCRIPTION OF SYMBOLS ... Battery 14 ... Drive motor 15 ... Temperature sensor 16 ... Discharge circuit 20 ... Power supply 21 ... Backup power supply 22 ... Discharge switch 23 ... Discharge resistor 24 ... Discharge control part 25 ... Charge control part 26 ... Unexpected time calculation part 27 ... Potential difference state Judgment part

Claims (3)

A smoothing capacitor that converts DC power to AC power, is connected in parallel to the DC power side of an inverter that converts the AC power to the DC power, and stabilizes the DC power;
Discharging the power stored in the smoothing capacitor until the voltage of the smoothing capacitor reaches a predetermined voltage that is not zero until a predetermined time elapses after the system of the vehicle on which the inverter is mounted is turned off ; and A discharge controller for determining whether or not a power supply voltage is supplied to the inverter control device ;
A discharge circuit that discharges the electric power stored in the smoothing capacitor until the voltage of the smoothing capacitor becomes zero when the discharge control unit determines that a power supply voltage is not supplied to the inverter control device ;
An inverter control device comprising: If the discharge control unit determines that the power supply voltage is not supplied to the inverter control device even when the vehicle system is off, the discharge circuit sets the voltage of the smoothing capacitor to zero. The inverter control device according to claim 1, wherein the electric power stored in the smoothing capacitor is discharged until   The inverter control device according to claim 1, wherein the discharge circuit includes a normally closed type discharge switch that is de-energized in a normal state.

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