JP5776585B2 - Driving device for switching element - Google Patents

Description

  The present invention relates to a switching element driving apparatus in which a voltage-controlled switching element is a driving target switching element.

  Conventionally, as can be seen in Patent Document 1 below, when the driving state of a semiconductor switching element (IGBT) is switched from one state to the other state between an on state and an off state, the gate charge for making the other state A technique (so-called active gate control) for switching the setting of the charging speed is known. This technique will be described mainly with respect to the charge of the gate charge for turning off the switching element. A pair of charging paths is connected to the gate of the switching element. Each of these charging paths is provided with a resistor, and the resistance values of these resistors are different from each other. Each of the charging paths is provided with a transistor for opening and closing the charging path.

  In such a configuration, first, an off operation command for the switching element is input, and a transistor provided in the same charging path as the resistor having the lower resistance value is turned on, thereby setting the charging speed to a high speed gate. Charge is charged. After that, the transistor is turned off, and the transistor provided in the same charging path as the resistor having the higher resistance value is turned on, so that the gate charge is charged with the charging speed set to a low speed. .

  According to the above technique, it is possible to suppress an increase in surge voltage that occurs when the driving state of the switching element is switched from one state to the other state between the on state and the off state, and to reduce switching loss. it can.

Japanese Patent No. 3339311

  By the way, if an abnormality occurs in the function of switching the setting of the charge rate of the gate charge such as the above transistor, the charge rate is deviated from an appropriate one, so that the surge voltage cannot be suppressed or the switching loss cannot be reduced. There is a risk.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a driving device for a switching element capable of detecting that an abnormality has occurred in a function for switching setting of a charging speed. is there.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

The present invention comprises a charging means for charging an opening / closing control terminal of the drive target switching element with a charge for turning on or off the drive target switching element (S * #) which is a voltage control type switching element, The charging means includes a charging path (Lda, Ldb) connected to the opening / closing control terminal, and an opening / closing element (30a, 30b) provided in the charging path and operated on and off to open and close the charging path. A charge speed setting means for switching the charge charge speed setting to either a high speed or a low speed by changing the operating state of the switching element, and the temperature of the switching element to be driven is deviated from a specified temperature. On the basis of an abnormality in which the actual charging speed is lower than the charging speed when no abnormality has occurred in the charging means, or the charging means Abnormal abnormality increases the actual the charge rate than the charge rate when the non occurs, characterized in that it comprises an abnormality determining means for determining that has occurred in the charging unit.

  If an abnormality occurs in the function of switching the setting of the charging speed, the charge speed determined according to the operation state of the switching element may deviate from an appropriate charging speed for reducing the switching loss of the drive target switching element. In this case, when the switching loss changes, the actual temperature of the driving target switching element deviates from the temperature at which the abnormality does not occur. Focusing on this point, the temperature of the drive target switching element is a parameter for determining whether or not there is an abnormality in the function of switching the setting of the charging speed. Here, in the said invention, it can detect that abnormality has arisen in the function which switches the setting of charging speed by providing an abnormality determination means.

  Note that the charge for changing the drive state of the drive target switching element from one of the on state and the off state to the other is not limited to a positive charge but may be a negative charge. For this reason, charging a negative charge to the switching control terminal means discharging a positive charge from the switching control terminal.

1 is a system configuration diagram according to a first embodiment. FIG. The block diagram of the drive unit concerning the embodiment. The figure which shows the outline | summary of the discharge process concerning the embodiment. The flowchart which shows the procedure of the abnormality determination process concerning the embodiment. The flowchart which shows the procedure of the fail safe process concerning the embodiment. The figure which shows the outline | summary of the test | inspection process which sets the regulation temperature concerning the embodiment. The flowchart which shows the procedure of the abnormality determination process concerning 2nd Embodiment. The figure which shows the acquisition timing of the sense voltage concerning the embodiment. The flowchart which shows the procedure of the abnormality determination process concerning 3rd Embodiment.

(First embodiment)
Hereinafter, a first embodiment in which a driving device for a switching element according to the present invention is applied to an electric vehicle including only a rotating machine as an in-vehicle main machine will be described with reference to the drawings.

  FIG. 1 shows an overall configuration of a system according to the present embodiment.

  The motor generator 10 is an in-vehicle main machine and is mechanically coupled to drive wheels (not shown). The motor generator 10 is connected to the high voltage battery 12 via an inverter IV and a converter CV as a DC power source. Here, converter CV includes capacitor C, a pair of switching elements Scp and Scn connected in parallel to capacitor C, and a reactor L that connects a connection point between the pair of switching elements Scp and Scn and the positive electrode of high-voltage battery 12. And. Specifically, the converter CV has a function of boosting the voltage of the high voltage battery 12 (for example, “288V”) up to a predetermined voltage (for example, “666V”) by turning on / off the switching elements Scp, Scn.

  On the other hand, the inverter IV includes a serial connection body of switching elements Sup and Sun, a serial connection body of switching elements Svp and Svn, and a serial connection body of switching elements Swp and Swn. Connection points of these series connection bodies are respectively connected to the U, V, and W phases of the motor generator 10.

  In the present embodiment, an insulated gate bipolar transistor (IGBT) is used as the switching element S * # (* = c, u, v, w; # = p, n). In addition, a free wheel diode D * # is connected in antiparallel to each of the switching elements S * #.

  The control device 14 operates the inverter IV and the converter CV in order to perform normal control for controlling the control amount (for example, torque) of the motor generator 10 as desired using the low voltage battery 16 as a power source. Specifically, control device 14 operates switching elements Scp and Scn of converter CV by outputting operation signals gcp and gcn to drive unit DU. Further, the control device 14 outputs the operation signals gup, gun, gvp, gvn, gwp, gwn generated by the well-known sine wave PWM control or the like to the drive unit DU, thereby switching the switching elements Sup, Sun, Svp of the inverter IV. , Svn, Swp, Swn. Here, the high-potential side operation signal g * p and the corresponding low-potential side operation signal g * n are complementary to each other. In other words, the high-potential side switching element S * p and the corresponding low-potential side switching element S * n are alternately turned on.

  Incidentally, the normal control of the motor generator 10 is, for example, adjusting the output torque of the motor generator 10 according to the operation of an operation member (for example, an accelerator pedal) that is a user's operation target to indicate the output torque of the motor generator 10. This refers to the control that is possible.

  The interface 18 is a device for exchanging signals between the high voltage system including the high voltage battery 12 and the low voltage system including the low voltage battery 16 while insulating the interface. In the present embodiment, an optical insulating element (photocoupler) is used as the interface 18.

  The control device 14 includes a memory 14a (nonvolatile memory) as storage means. The converter CV, the inverter IV, and the control device 14 constitute a power control unit.

  Next, the configuration of the drive unit DU according to the present embodiment will be described with reference to FIG.

  As shown in the figure, the drive unit DU includes a drive IC 20 that is a one-chip semiconductor integrated circuit. A constant voltage power supply 24 for applying a voltage to the switching control terminal (gate) of the switching element S * # is connected to the terminal T1 of the drive IC 20 via the charging resistor 22.

  The terminal T1 is connected to a terminal T2 of the drive IC 20 through a P-channel MOSFET (charging switching element 26). Terminal T2 is connected to the gate of switching element S * #.

  The gate of the switching element S * # is connected to the terminal T3 of the drive IC 20 via the first discharging resistor 28a, and the terminal T3 is connected to the N-channel MOSFET (first discharging switching element 30a). And connected to a terminal T4 of the drive IC 20. The gate of the switching element S * # is connected to the terminal T5 of the drive IC 20 via the second discharging resistor 28b, and the terminal T5 is an N-channel MOSFET (second discharging switching element 30b). To the terminal T4. The terminal T4 is connected to the emitter of the switching element S * #.

  Incidentally, the resistance values Ra and Rb of the first discharge resistor 28a and the second discharge resistor 28b may be the same or different from each other.

  The switching element S * # includes a sense terminal St that outputs a minute current having a correlation with a collector current. The sense terminal St is connected to the emitter of the switching element S * # via a resistor (sense resistor 32). As a result, a voltage drop occurs in the sense resistor 32 due to a minute current output from the sense terminal St. Therefore, the potential on the sense terminal St side of the sense resistor 32 (hereinafter, sense voltage Vse) is correlated with the collector current. State quantity. The sense voltage Vse is input to the drive control unit 34 in the drive IC 20 via the terminal T6 of the drive IC 20.

  Incidentally, in the present embodiment, the sense voltage Vse when the potential on the sense terminal St side among the both ends of the sense resistor 32 is higher than the potential of the emitter is defined as positive. The emitter potential is set to “0”.

  The terminal T6 is connected to the non-inverting input terminal of the comparator 38. A voltage obtained by dividing the terminal voltage of the constant voltage power supply 40 by the resistors 42 and 44 (hereinafter referred to as a reference voltage Vref) is applied to the inverting input terminal of the comparator 38.

  A temperature sensitive diode SD * # for detecting the temperature of the switching element S * # (hereinafter, element temperature) is provided in the vicinity of the switching element S * #. The temperature sensitive diode SD * # is supplied with a charge from a constant voltage power supply 46 externally attached to the drive IC 20 via a constant current source 48. The cathode of the temperature sensitive diode SD * # is connected to the emitter, and the anode is connected to the terminal T7 of the drive IC 20. According to such a configuration, the temperature sensitive diode SD * # outputs an output voltage corresponding to the temperature of the switching element S * #. The output voltage of the temperature sensitive diode SD * # is input to the drive control unit 34 via the terminal T7. The drive control unit 34 detects the element temperature TD based on the output voltage of the temperature sensitive diode SD * #.

  The drive control unit 34 outputs information on the sense voltage Vse and the element temperature TD to the low voltage system (control device 14) via the terminal T8 of the drive IC 20 and the interface 18.

  The gate of the switching element S * # is further connected to the terminal T4 via the soft cutoff resistor 50, the terminal T9 of the drive IC 20 and the N-channel MOSFET (soft cutoff switching element 52).

  The drive control unit 34 performs overcurrent protection processing and gate charge charging / discharging processing.

  First, the overcurrent protection process will be described.

  In this process, when it is determined that the sense voltage Vse is equal to or higher than the threshold voltage Vth over a predetermined time, the soft-blocking switching element 52 is turned on to forcibly turn off the switching element S * #. is there. Here, the threshold voltage Vth is set to a sense voltage corresponding to the upper limit value of the collector current capable of maintaining the reliability of the switching element S * #.

  According to this process, when the time during which a large current flows through the switching element S * # is continued for a predetermined time, the soft cutoff switching element 52 is turned on and the gate charge is discharged. Thereby, switching element S * # is forcibly turned off. Here, the soft-blocking resistor 50 is for increasing the resistance value of the discharge path of the gate charge. More specifically, the resistance value of the soft blocking resistor 50 is set higher than the resistance value of the first discharging resistor 28a and the resistance value of the second discharging resistor 28b. This is because, under a situation where the collector current is excessive, if the switching element S * # is switched from the ON state to the OFF state, in other words, if the cutoff speed between the collector and the emitter is increased, the surge voltage becomes excessive. This is because there is a possibility of becoming.

  When overcurrent protection processing is performed, processing for outputting a fail signal FL and processing for stopping driving of the charging switching element 26, the first discharging switching element 30a, and the second discharging switching element 30b. Is also performed. The fail signal FL is output to the low voltage system via the terminal T10 of the drive IC 20 and the interface 18. Then, a shutdown process for forcibly turning off the switching element S * # of the inverter IV and the converter CV is performed by the fail signal FL.

  Next, the charge / discharge process of gate charge will be described.

  First, the gate charging process will be described. In the present embodiment, the charging process is performed by constant current control. Specifically, in the constant current control, when the operation signal g * # input via the terminal T11 of the drive IC 20 is an ON operation command, the voltage drop amount of the charging resistor 22 is set to the target value (for example, 1V). ), The gate voltage of the charging switching element 26 is manipulated. Thus, the surge voltage generated when the switching element S * # is turned on is suppressed by controlling the charging current of the gate of the switching element S * # to a constant value. During the period when the charging process is performed, the first and second discharging switching elements 30a and 30b are turned off.

  Next, the gate discharge process will be described. In this embodiment, the gate charge discharge (negative charge charge) is connected to the gate of the switching element S * # during the period from the start to the completion of the discharge. Active gate control is performed to switch the resistance value of the discharge path (charge path of negative charge) from low to high. That is, control is performed to switch the setting of the discharge rate of the gate charge from a high rate to a low rate. This control is for suppressing an increase in surge voltage and switching loss when the switching element S * # is switched from the off state to the on state.

  Specifically, when the operation signal g * # is an off operation command, both the first discharge switching element 30a and the second discharge switching element 30b are turned on, and the discharge rate of the gate charge is set. High speed. Thus, the first discharge path Lda connecting the gate and emitter of the switching element S * # via the first discharge resistor 28a and the first discharge switching element 30a, and the second discharge resistor The gate charge is discharged by the second discharge path Ldb connecting the gate and the emitter via 28b and the second discharge switching element 30b. After that, by switching the second discharge switching element 30b of these switching elements 30a and 30b to the off operation, the setting of the discharge speed is switched to a low speed. As a result, the gate charge is discharged through the first discharge path Lda. Note that the charging switching element 26 is turned off during the period in which the discharging process is performed.

  Here, in the present embodiment, as shown in FIG. 3, the timing for switching the setting of the discharge speed from the high speed to the low speed is grasped based on the sense voltage Vse. Specifically, FIG. 3 shows changes in the gate voltage Vge, the collector current Ic, the sense voltage Vse, and the collector-emitter voltage Vce.

  As shown in the figure, after the operation signal g * # is switched to the OFF operation command at the time t1 and the discharge of the gate charge is started, the sense voltage Vse crosses the reference voltage Vref from the bottom to the top (time t2). Is grasped as the timing for switching the setting of the discharge speed. Here, the sense voltage Vse can be used for grasping the timing because the sense voltage Vse greatly increases in the vicinity of time t2 within the period in which the switching element S * # is shifted from the on state to the off state. This is because it occurs. Specifically, under the circumstances where such a phenomenon occurs, the switching speed of the discharge speed setting that can reduce the switching loss while reducing the surge voltage when the switching element S * # is switched from the on state to the off state, and the sense voltage This is because it is possible to relate the timing at which Vse crosses the reference voltage Vref from the bottom to the top. Here, as the time from the switching to the OFF operation command to the switching timing is shorter, the surge voltage reducing effect tends to increase and the switching loss reducing effect tends to decrease.

  After that, at time t3 when the sense voltage Vse crosses the reference voltage Vref from the top to the bottom, the setting of the gate charge discharge rate is again made high. In addition, it is considered that the phenomenon that the sense voltage Vse greatly increases occurs when a surge voltage is superimposed on the sense voltage Vse via a parasitic capacitance between the collector or emitter and gate of the switching element S * #.

  Next, the abnormality determination process executed by the control device 14 will be described.

  This process is performed using an active gate control function (first discharge resistor 28a, second discharge resistor 28b, first discharge current) using the element temperature TD detected based on the output voltage of the temperature sensitive diode SD * #. The discharge switching element 30a, the second discharge switching element 30b, the first discharge path Lda, and the second discharge path Ldb) determine whether or not an abnormality has occurred.

  In the present embodiment, the abnormality determination process is executed on the condition that no abnormality has occurred in the functions related to the charging process (charging resistor 22 and charging switching element 26). Here, as a function abnormality determination method related to the charging process, for example, when the sense voltage Vse is determined to be “0” in the period when the ON operation command is issued, the charging resistor 22 or the charging switching is performed. It may be determined that an open failure has occurred in the element 26. On the other hand, when it is determined that no voltage drop occurs in the charging resistor 22 in spite of the increase in the sense voltage Vse during the period when the ON operation command is issued, a short-circuit failure has occurred in the charging resistor 22. You may judge that. On the other hand, if it is determined that a voltage drop occurs in the charging resistor 22 during the period in which the OFF operation command is issued, it may be determined that a short circuit failure has occurred in the charging switching element 26.

  FIG. 4 shows a procedure of abnormality determination processing executed by the control device 14. This process is executed for each switching element S * #.

  In this series of processes, first, in step S10, it is determined whether or not the operation signal g * # is an ON operation command.

  If an affirmative determination is made in step S10, the process proceeds to step S12, and it is determined whether or not the element temperature TD output from the drive control unit 34 exceeds the upper limit temperature Tα in the period when the on operation command is issued. Here, the upper limit temperature Tα is set to a temperature lower than the upper limit value of the element temperature (hereinafter, allowable temperature Tlimit) that can maintain the reliability of the switching element S * #. In particular, the upper limit temperature Tα is an upper limit value (maximum current Imax) that can be obtained during normal use of the power control unit (during normal control of the motor generator 10) in a situation where no abnormality has occurred in the active gate control function. In this case, the upper limit (fixed value) that the element temperature can take is set. The upper limit temperature Tα is set separately for each of the switching elements S * #. This process includes the first discharge resistor 28a, the first discharge switching element 30a, the second discharge resistor 28b, the second discharge switching element 30b, the first discharge path Lda, or the second discharge This is a process for determining whether or not an open failure has occurred in the discharge path Ldb. That is, it is a process for determining whether or not an abnormality has occurred where the actual discharge rate is lower than the discharge rate when no abnormality has occurred in the active gate control function.

  That is, when the open failure occurs, the gate charge discharge path becomes the first discharge path Lda or the second discharge path Ldb in a period in which the discharge speed is set to a high speed, and the resistance value of the gate charge discharge path Becomes higher than the resistance value of the discharge path when the open failure does not occur. When the resistance value of the discharge path increases, the switching loss increases, so that the amount of heat generated by the switching element S * # increases and the element temperature rises. Paying attention to these points, the processing of this step is provided.

  The upper limit temperature Tα is stored in the memory 14a. The setting and storage method of the upper limit temperature Tα will be described in detail later.

  If an affirmative determination is made in step S12, the process proceeds to step S14, and the first discharge resistor 28a, the first discharge switching element 30a, the second discharge resistor 28b, and the second discharge switching element. 30b, it is determined that an open failure has occurred in the first discharge path Lda or the second discharge path Ldb.

  In the subsequent step S16, the value of the abnormality determination flag F is set to “1”. Here, the abnormality determination flag F indicates that the open failure has occurred by “1”, and indicates that the open failure has not occurred by “0”. This process is a process for notifying the execution unit of the fail safe process in the control device 14 that the open failure has occurred.

  If a negative determination is made in steps S10 and S12 described above, or if the process in step S16 is completed, the series of processes is temporarily terminated.

  Next, the fail safe process executed by the control device 14 will be described. FIG. 5 is a diagram illustrating a procedure of fail-safe processing.

  In this series of processing, first, in step S18, it is determined whether or not the value of the abnormality determination flag F is “1”. In addition to this process, a notification process for notifying the user that an abnormality has occurred is performed.

  If an affirmative determination is made in step S18, the process proceeds to step S20 to determine whether or not the element temperature TD exceeds the allowable temperature Tlimit. This process is a process for avoiding an excessive decrease in the reliability of the switching element S * #.

  That is, the first discharge resistor 28a, the first discharge switching element 30a, the second discharge resistor 28b, the second discharge switching element 30b, the first discharge path Lda, or the second discharge path. If an open failure occurs in Ldb and the discharge process is performed in a state where the discharge rate is reduced, the switching loss increases. When the switching loss increases, the amount of heat generated by the switching element S * # increases, and the reliability of the switching element S * # may be excessively reduced. From the viewpoint of avoiding such a situation, when an affirmative determination is made in step S18, it is conceivable to immediately stop driving of all the switching elements S * #. However, for example, if the driving of the switching element S * # is stopped while the vehicle is traveling, there is a risk that inconveniences such as drivability may be reduced and limp home may not be performed properly. In order to avoid such inconvenience, while it is determined in this step that the reliability of the switching element S * # is not excessively lowered, the continuation of the discharge process is permitted and the continuation of the driving of the switching element S * # is permitted. .

  If a negative determination is made in step S20, the process proceeds to step S21, and the continuation of driving of the switching element S * # is permitted.

  On the other hand, if an affirmative determination is made in step S20, it is determined that the reliability of the switching element S * # may be excessively reduced, and the process proceeds to step S22. In step S22, the shutdown process is performed.

  In addition, when the process of step S21, S22 is completed, this series of processes is once complete | finished.

  Next, a method for setting the upper limit temperature Tα and a method for storing the upper limit temperature Tα in the memory 14a will be described in detail. In the present embodiment, the upper limit value that the element temperature can take when the collector current is set to the maximum current Imax is stored in the memory 14a as the upper limit temperature Tα in the inspection process of the power control unit before shipment from the factory.

  FIG. 6 is a flowchart showing the steps involved in setting and storing the upper limit temperature Tα in the inspection process of the power control unit.

  First, in step S100, the maximum current Imax is circulated through each of the switching elements S * #. Here, for example, the maximum current Imax corresponding to each of the converter CV and the inverter IV is distributed to each of the switching elements Scp, Scn and the switching elements S ¥ p, S ¥ n (¥ = u, v, w). That's fine. More specifically, for example, the maximum current Imax may be circulated by the sine wave PWM control for the switching elements S ¥ p, S ¥ n of the inverter IV.

  In the subsequent step S102, the maximum value of the element temperature TD when the maximum current Imax is circulated is detected as the upper limit temperature Tα for each of the switching elements S * #.

  In the subsequent step S104, the upper limit temperature Tα for each of the switching elements S * # is stored in the memory 14a.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The upper limit value that the element temperature can take when the upper limit temperature Tα is lower than the allowable temperature Tlimit and the collector current is set to the maximum current Imax in a situation where no abnormality occurs in the active gate control function. Set to. For this reason, it is possible to set a threshold value for detecting the abnormality before the reliability of the switching element S * # is greatly reduced. Further, according to the above setting, the upper limit temperature Tα is set to a fixed value, so that the abnormality determination process can be simplified.

  (2) When it is determined that the element temperature TD exceeds the upper limit temperature Tα during the period in which the ON operation command is issued, the first discharge resistor 28a, the first discharge switching element 30a, and the second discharge resistor It was determined that an open failure occurred in the body 28b, the second discharge switching element 30b, the first discharge path Lda, or the second discharge path Ldb. That is, it is possible to appropriately detect that an abnormality has occurred in the active gate control function.

  (3) When it is determined by the abnormality determination process that the open failure has occurred, the switching element S * # is allowed to continue to be driven until it is determined that the element temperature TD reaches the allowable temperature Tlimit. Thereby, the limp home of a vehicle can be performed appropriately.

  (4) In the inspection process before the factory shipment of the power control unit, the upper limit temperature Tα for each of the switching elements S * # mounted in the unit is stored in the memory 14a. The upper limit temperature Tα stored in the memory 14a is used for the abnormality determination process. The element temperature with respect to the collector current may differ depending on the individual difference of the switching element S * # and the arrangement location of the switching element S * # in the inverter IV and the converter CV. For this reason, according to the setting method of the upper limit temperature Tα in the above-described inspection process, the upper limit temperature Tα reflecting individual differences and arrangement locations of the switching elements S * # can be set individually for each of the switching elements S * #. it can. Thereby, the abnormality detection accuracy of the active gate control function can be increased.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the present embodiment, in the inspection process of the power control unit before shipment from the factory, the collector current that flows through each of the switching elements S * # is set to various values. Then, an upper limit value that the element temperature can take for each collector current is detected as the upper limit temperature TH, and the detected upper limit temperature TH is associated with the sense voltage and stored in the memory 14a. Then, the upper limit temperature TH used for the abnormality determination process is set higher as the sense voltage Vse is higher. Such a setting is a setting for increasing the detection accuracy of the open failure of the first discharging resistor 28a and the like.

  That is, the device temperature tends to increase as the collector current increases. That is, the higher the sense voltage Vse, the higher the upper limit temperature for determining whether or not the open failure has occurred. In view of these points, by setting the upper limit temperature higher as the sense voltage Vse is higher, for example, the setting accuracy of the upper limit temperature TH when the collector current is small can be increased, and the detection accuracy of the open fault can be increased. it can.

  FIG. 7 shows a procedure of abnormality determination processing according to the present embodiment that is executed by the control device 14. In FIG. 7, the same steps as those in FIG. 4 are given the same step numbers for the sake of convenience.

  In this series of processes, when an affirmative determination is made in step S10, the process proceeds to step S24, and the operation signal g * # is switched to the on operation command (both the first and second discharge switching elements 30a and 30b). Wait until the specified time TA has elapsed). This process is a process for avoiding a decrease in detection accuracy of the open failure of the first discharging resistor 28a and the like.

  That is, the collector current (sense voltage) is not stable immediately after the first and second discharge switching elements 30a and 30b are turned on. When the upper limit temperature TH is set in step S26 to be described later based on the element temperature TD under such circumstances, the relationship between the upper limit temperature TH and the actually detected sense voltage is the relationship between the upper limit temperature TH and the sense voltage determined in the inspection process. There is a risk of dislodging. In this case, there is a possibility that it is erroneously determined that the open failure has occurred even though the open failure has not occurred in the first discharge resistor 28a and the like. In order to avoid such a situation, as shown in FIG. 8, it is a period (time t1 to t3) in which an ON operation command is issued, and a period after a timing when a predetermined time TA has elapsed since switching to the ON operation command ( The sense voltage Vse at an arbitrary timing between times t2 and t3) is used for setting the upper limit temperature TH.

  In the process of this step, as shown in the figure, the sense voltage Vse greatly increases immediately after the first and second discharge switching elements 30a and 30b are turned on by switching to the on operation command. This is also a process for avoiding a drop in the detection accuracy of the open failure due to the phenomenon.

  When one of the pair of switching elements S * p on the high potential side and switching element S * n on the low potential side connected in series is turned on, the recovery current is connected to the free wheel diode connected in antiparallel with the other. Flows. Due to this recovery current, a surge voltage is generated in the free wheel diode and the switching element connected in parallel thereto. This surge voltage is superimposed on the sense voltage Vse via the parasitic capacitance between the collector and emitter and gate of the switching element S * # to be turned on. In this way, it is considered that a phenomenon that the sense voltage Vse greatly increases occurs even when the switching element S * # is turned on.

  Here, when the upper limit temperature TH is set based on the sense voltage Vse immediately after the first and second discharge switching elements 30a and 30b are turned on, the upper limit temperature is caused by the phenomenon that the sense voltage Vse increases greatly. TH may be set high. In this case, it is determined that the actual element temperature TD is lower than the excessively set upper limit temperature TH in spite of the occurrence of an open failure in the first discharge resistor 28a and the like. There is a risk of misjudgment that no failure has occurred.

  Incidentally, there is a possibility that the soft shut-off function in the overcurrent protection process may malfunction due to the phenomenon that the sense voltage Vse greatly increases. In order to avoid such a malfunction, for example, the sense voltage Vse used for the overcurrent protection process is disabled until the phenomenon that the sense voltage Vse increases significantly after the operation signal g * # is switched to the on operation command is eliminated. It is desirable to perform processing. Since this process is not directly related to the abnormality determination process that is a feature of the present embodiment, detailed description thereof is omitted.

  In the subsequent step S26, a process for setting the upper limit temperature TH higher as the sense voltage Vse is higher is performed. In the present embodiment, the relationship between the sense voltage Vse and the upper limit temperature TH is stored in the memory 14a with the upper limit value of the sense voltage Vse for setting the upper limit temperature TH as the threshold voltage Vth. Here, the upper limit temperature Tmax corresponding to the case where the sense voltage Vse is set to the threshold voltage Vth is set as a temperature lower than the allowable temperature Tlimit.

  In the subsequent step S28, it is determined whether or not the element temperature TD exceeds the upper limit temperature TH in a period in which the on operation command is issued and in a period after the timing when the specified time TA elapses after switching to the on operation command. To do. If a positive determination is made in step S28, the process proceeds to step S14.

  If a negative determination is made in steps S10 and S28 described above, or if the process of step S16 is completed, the series of processes is temporarily terminated.

  As described above, in the present embodiment, the sense voltage Vse in the period in which the on-operation command is issued and after the timing when the specified time TA has elapsed since switching to the on-operation command is used as the upper limit temperature TH. As a result, the detection accuracy of the open failure of the first discharge resistor 28a and the like is reduced due to the collector current not being stabilized immediately after switching to the ON operation command or the sense voltage being greatly increased. Can be avoided. Furthermore, since the upper limit temperature TH is set higher as the sense voltage Vse is higher, the detection accuracy of the open failure can be increased.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  In the present embodiment, in the inspection process of the power control unit before shipment from the factory, the collector current that flows through each of the switching elements S * # is set to various values. Then, the lower limit value that the element temperature can take for each collector current is detected as the lower limit temperature TL, and the detected lower limit temperature TL is associated with the sense voltage and stored in the memory 14a. Then, as abnormality determination processing, processing is performed to determine whether or not a short failure has occurred in the first discharging resistor 28a or the second discharging resistor 28b using the lower limit temperature TL. That is, processing is performed to determine whether or not an abnormality has occurred in which the actual discharge rate is higher than the discharge rate when no abnormality has occurred in the active gate control function. This determination method uses the following principle.

  When no abnormality occurs in the active gate control function, the element temperature is usually within a predetermined temperature range with respect to a predetermined collector current. On the other hand, when the short circuit failure occurs, the switching loss decreases due to the decrease in the resistance value of the first discharge path Lda or the second discharge path Ldb, and the heat generation amount of the switching element S * # decreases. And if calorific value falls, element temperature will fall below the lower limit of the above-mentioned temperature range.

  FIG. 9 shows the procedure of abnormality determination processing according to this embodiment. In FIG. 9, the same steps as those in FIG. 7 are given the same step numbers for the sake of convenience.

  In this series of processes, when an affirmative determination is made in step S24, the process proceeds to step S30, and a process of setting the upper limit temperature TH and the lower limit temperature TL higher as the sense voltage Vse is higher is performed.

  If an affirmative determination is made in the subsequent step S28, the process proceeds to step S14. On the other hand, if a negative determination is made in step S28, the process proceeds to step S32, and is a period in which the on-operation command is issued and over a period after the timing when the specified time TA elapses after switching to the on-operation command. Thus, it is determined whether the element temperature TD continues and falls below the lower limit temperature TL. This process is a process for determining whether or not a short failure has occurred in the first discharge resistor 28a or the second discharge resistor 28b.

  If an affirmative determination is made in step S32, the process proceeds to step S34 to determine that a short fault has occurred in the first discharge resistor 28a or the second discharge resistor 28b. Then, the process proceeds to step S16.

  If a negative determination is made in steps S10 and S32, or if the process of step S16 is completed, the series of processes is temporarily terminated.

  As described above, in the present embodiment, by performing the abnormality determination process of the above aspect, in addition to the effects obtained in the second embodiment, a short failure has occurred in the first discharge resistor 28a and the like. Can also be detected.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  The setting method for the specified temperatures (upper temperature Tα, TH, lower limit temperature TL) is not limited to the setting method in the inspection process. For example, in a mass-produced switching element, a technique may be adopted in which a specified temperature is set in advance by experiments or the like using a switching element whose element temperature characteristic is a central characteristic with respect to the collector current. In this case, for example, a common specified temperature is set for each of the switching elements S * #.

  Further, for example, a method of setting a specified temperature during normal control of the motor generator 10 may be employed. Specifically, for example, in the second embodiment, first, the upper limit temperature set by using the switching element having the central characteristic in the inspection process before factory shipment is stored in the memory 14a as an initial value. After that, there is a method in which the element temperature when the switching element S * # is turned on during the normal control is stored in the memory 14a in association with the sense voltage, and the upper limit temperature is updated. According to such a method, when the environment around the power control unit when the initial value is determined (for example, the ambient temperature) and the actual use environment of the vehicle are greatly different, the use environment of the vehicle becomes the element temperature. It is thought that the upper limit temperature can be set reflecting the effect.

  In the first embodiment described above, the execution subject of the abnormality determination process is the control device 14, but is not limited thereto. For example, the drive control unit 34 may be the execution subject. Hereinafter, an example of abnormality determination processing in this case will be described.

  The drive control unit 34 corresponding to each of the switching elements S * # includes a memory (nonvolatile memory) as a storage unit. For example, the upper limit temperature Tα described in the first embodiment is stored in the memory in the inspection process. Is remembered.

  In such a configuration, when the drive control unit 34 determines that an open failure has occurred in the first discharge resistor 28a and the like, the fail signal FL is output to notify the control device 14 of the fact. Incidentally, it is desirable to make the fail signal FL output when the overcurrent protection processing is performed different from the fail signal FL output when it is determined that the open failure has occurred. Specifically, for example, a pulse is used as the fail signal FL, and the fail signal FL may be made different by changing the frequency of the pulse. Thereby, in the control apparatus 14, it is possible to appropriately discriminate between an abnormality in which a large current flows through the switching element S * # and the open failure.

  The method for switching the setting of the discharge speed is not limited to that exemplified in the first embodiment. For example, the following method may be employed.

  The resistance value Ra of the first discharging resistor 28a is set lower than the resistance value Rb of the second discharging resistor 28b. In such a configuration, the first discharge switching element 30a is turned on and the second discharge switching element 30b is turned off, so that the discharge speed is set to a high speed. As a result, the gate charge is discharged through the first discharge path Lda. After that, the first discharge switching element 30a is switched to the off operation and the second discharge switching element 30b is switched to the on operation, thereby switching the discharge speed setting to a low speed. As a result, the gate charge is discharged through the second discharge path Ldb.

  The above abnormality determination process can also be applied to such a configuration. Specifically, for example, in the third embodiment, when it is determined that the element temperature TD is lower than the lower limit temperature TL, there is a short circuit failure in the first discharge resistor 28a or the second discharge resistor 28b. It can be determined that it has occurred.

  In each of the above embodiments, active gate control is performed only in the discharge process, but the present invention is not limited to this. For example, active gate control may be performed in the charging process together with the discharging process or only in the charging process. In this case, instead of the circuit configuration for performing constant current control, for example, the constant voltage power supply 24 and the gate of the switching element S * # are connected by a pair of charging paths (positive charge charging paths) and the charging is performed. What is necessary is just to employ | adopt the circuit structure provided with the switching element (for example, MOSFET) and the resistor in each of the path | routes.

  In such a configuration, only one of these switching elements is turned on to set the gate charge (positive charge) charge speed to a low speed. Thereafter, the charging speed setting is changed to a high speed by turning on both opening and closing elements.

  Even when such a configuration is adopted, it is possible to perform an abnormality determination process for the active gate control function in the charging process. Specifically, the case where the active gate control is performed only in the charging process will be described. For example, when it is determined that the element temperature TD exceeds the upper limit temperature in the period when the ON operation command is issued, the ON operation is performed in the latter half of the charging process. Open / close failure in switching element, charging path provided with this switching element, or resistor provided in this charging path (actual speed rather than charging speed when there is no abnormality in active gate control function in charging process) What is necessary is just to judge that the abnormality which the charging speed becomes low has occurred.

  Further, the case where active gate control is performed in both the charging process and the discharging process will be described. For example, in the first embodiment, the actual charging speed is higher than the charging speed when no abnormality occurs in the active gate control function. The upper limit temperature is set to the lower one of the element temperature when the abnormality occurs when the abnormality becomes low and the element temperature when the abnormality occurs when the actual discharge rate is lower than the discharge rate when the abnormality does not occur. do it.

  In the third embodiment, a control logic that determines only the presence or absence of an abnormality in which the actual discharge rate is higher than the discharge rate when no abnormality has occurred in the active gate control function may be employed.

  The method for grasping the switching timing of the discharge speed setting is not limited to the method exemplified in the first embodiment. For example, a method of grasping, as the switching timing, a timing at which the change speed (rise speed) of the sense voltage Vse exceeds a specified speed may be employed.

  Further, the method for grasping the switching timing of the discharge speed setting is not limited to the one based on the sense voltage. For example, a method of grasping the switching timing based on the collector-emitter voltage Vce may be employed. In this case, specifically, for example, in the first embodiment, after switching to the OFF operation command, the timing at which the collector-emitter voltage Vce crosses a predetermined voltage from the bottom to the top is grasped as the switching timing. Good.

  Furthermore, for example, a method of grasping the switching timing using a gate voltage or an off operation command may be employed. In this case, specifically, for example, the timing at which the gate voltage Vge starts to decrease due to the discharge process or the timing after the predetermined time has elapsed from the timing at which the OFF operation command is input (for example, the time t1 in FIG. 3). What is necessary is just to employ | adopt the method grasped | ascertained as the said switching timing.

  In each of the above embodiments, the active gate control that switches the setting of the discharge rate in the middle of the period from the start to the completion of the discharge of the gate charge is adopted, but the present invention is not limited thereto. For example, without changing the discharge speed setting in the middle of the above period, the discharge speed setting is fixed to either the low speed or the high speed based on the collector current Ic (sense voltage Vse) during the period when the ON operation command is issued. Then, a control logic for performing a discharge process may be employed. The above control logic will be described in detail. When it is determined that the collector current Ic is equal to or higher than the specified current (> 0) during the period when the ON operation command is issued, the discharge speed setting is switched to a low speed and the discharge current is set. The discharge rate is fixed at a low rate in the process. On the other hand, when it is determined that the collector current Ic is less than the specified current during the period when the ON operation command is issued, the setting of the discharge speed is switched to a high speed, and the discharge speed is fixed at a high speed in the discharge process. This control is due to the fact that if the collector current during the period when the on operation command is issued is small, the collector-emitter voltage will be less than or equal to the allowable upper limit value even when the speed is turned off next time even if the speed is high.

  In each of the above embodiments, the circuit configuration in which the sense terminal St is connected to the emitter of the switching element S * # via the sense resistor 32 is adopted, but the present invention is not limited to this. For example, instead of the emitter, it may be connected to a member (for example, a power source) having the same potential as the emitter. In this case, the potential of the power source is variably set according to the actual potential of the emitter.

  The circuit configuration for switching the setting of the discharge speed to either the high speed or the low speed is not limited to the one exemplified in the first embodiment. For example, one discharge path connecting the gate and the emitter, a plurality of resistors provided in the discharge path, a short-circuit path short-circuiting both ends of these resistors, and on / off to open and close the short-circuit path You may employ | adopt the circuit structure provided with the switching element (for example, MOSFET) operated. In this case, the opening / closing element is turned on only in the initial stage when it is desired to set the discharge speed to a high speed. Thereafter, the discharge speed can be set to a low speed by turning off the open / close element.

  Further, as the above circuit configuration, for example, those described in (A) and (B) below may be adopted.

  (A) A discharge path connected to the gate is provided with an emitter or a switching element (for example, a MOSFET) that can switch the connection between the emitter and a portion having a lower potential than the emitter. In such a configuration, the opening / closing element is operated to connect the gate to a location where the potential is lower than that of the emitter, instead of connecting the gate and the emitter, only in the initial stage of the discharge process where the discharge rate is to be set to a high speed. . Then, the discharge speed setting is switched to a low speed by changing the operating state of the switching element to connect the gate to the emitter. In such a configuration, an abnormality in which the actual discharge rate is lower than the discharge rate when no abnormality has occurred in the active gate control is, for example, an abnormality in which the gate and the emitter are always connected by the switching element. is there.

  (B) A first switching element (for example, MOSFET) and a resistor are provided in a discharge path connected to the gate, and a power source is connected to the gate via a second switching element (for example, MOSFET). In such a configuration, the first opening / closing element is turned on at the start of the discharging process, and the second opening / closing element is turned off only in the initial stage of the discharging process where it is desired to set the discharge speed to a high speed. Thereafter, the second opening / closing element is turned on. According to such an operation, a current flows from the power source to the resistor in the discharge path, and a current flowing from the gate to the resistor decreases. Thereby, the discharge of the gate charge is prevented, and the setting of the discharge rate of the gate charge is switched from the high speed to the low speed. In such a configuration, the abnormality in which the actual discharge rate is higher than the discharge rate when no abnormality has occurred in the active gate control is, for example, an open failure of the second switching element.

  In the first embodiment, when the converter CV is not driven or when a configuration in which the inverter IV is directly connected to the high voltage battery 12 is employed, the high voltage battery 12 is used as a DC power source.

  The driving target switching element is not limited to the IGBT but may be a MOSFET, for example.

  -The vehicle to which the present invention is applied is not limited to an electric vehicle having only a rotating machine as an in-vehicle main unit. For example, the present invention may be applied to a hybrid vehicle including an internal combustion engine in addition to a rotating machine as an in-vehicle main machine. In this case, for example, when an affirmative determination is made in step S18 of FIG. 5, a shutdown process may be performed as a fail-safe process, and a process in which the driving power source of the vehicle is only the internal combustion engine may be performed.

  -The application object of this invention is not restricted to the power converter circuit mounted in a vehicle. The application object of the present invention is not limited to a power conversion circuit such as a converter or an inverter.

  14a ... Memory, 28a ... First discharge resistor, 28b ... Second discharge resistor, 30a ... First discharge switching element, 30b ... Second discharge switching element, Lda ... First discharge Path, Ldb ... second discharge path.

Claims (10)

Charging means for charging the open / close control terminal of the drive target switching element with a charge for turning on or off the drive target switching element (S * #) which is a voltage-controlled switching element;
The drive target switching element includes a sense terminal (St) that outputs a minute current having a correlation with a current flowing between the input and output terminals.
The output terminal of the driving target switching element or a member having the same potential as this terminal and the sense terminal are connected via a sense resistor (32),
The charging means includes
A charging path (Lda, Ldb) connected to the open / close control terminal;
An opening / closing element (30a, 30b) provided in the charging path and operated to be turned on and off to open and close the charging path;
Based on a sense voltage that is a potential difference between both ends of the sense resistor, a charging speed setting unit that switches a setting of a charging speed of the charge to either a high speed or a low speed by changing an operation state of the switching element;
Based on Rukoto temperature exceeded the upper limit temperature of the driven switching element, anomalies actual the charge rate than the charge rate when the abnormality in the charging device has not occurred is low occurs on the charging means An abnormality judging means for judging that the
Temperature setting means for setting the upper limit temperature to be higher as the sense voltage is higher during a period in which the switching element to be driven is turned on, and after a period of time after the specified time has elapsed since the start of the on operation. A drive device for a switching element, comprising: The driving target switching element includes a high potential side switching element (S * p) connected to the positive side of the DC power source (CV, 12) and a low potential side switching element (S) connected to the negative side of the DC power source. * N)
The high potential side switching element and the low potential side switching element are connected in series,
The high potential side switching element and the each of the low-potential side switching element, freewheel diode (D * #) drives the switching element according to claim 1, wherein the are connected in antiparallel. A storage means for storing the upper limit temperature;
The storage means stores, as the upper limit temperature, the temperature of the drive target switching element when a current is passed between the input / output terminals of the drive target switching element in an inspection process before shipment of the drive device,
Said abnormality determination means determines that the temperature of the switching element to be driven, based on Rukoto exceeded the upper limit temperature stored in the storage means, the charge rate is lower abnormality occurs in said charging means drive of the switching element according to claim 1 or 2, characterized in that. The abnormality determination means is based on the fact that the temperature of the driving switching element is lower than a lower limit temperature lower than the upper limit temperature, and the actual charging speed is higher than the charging speed when no abnormality occurs in the charging means. Is determined that an abnormality occurs in the charging means ,
The temperature setting means is a period during which the drive target switching element is turned on, and the lower the lower limit temperature, the higher the sense voltage in a period after the specified time has elapsed since the start of the on operation. set high for that drive the switching element according to any one of claims 1 to 3, characterized in. A storage means for storing the lower limit temperature;
The storage means stores, as the lower limit temperature, the temperature of the drive target switching element when a current is passed between the input / output terminals of the drive target switching element in an inspection process before shipment of the drive device,
The abnormality determining means determines that an abnormality that increases the charging speed is occurring in the charging means based on a temperature of the driving target switching element being lower than the lower limit temperature stored in the storage means. The switching element driving device according to claim 4. When it is determined by the abnormality determination means that the abnormality has occurred in the charging means, notification means for notifying information to that effect;
If information indicating that the abnormality is caused by the notification unit is notified, according to any one of claims 1 to 5, further comprising a fail-safe means for performing a predetermined fail-safe processing Switching element drive device. Charging means for charging the open / close control terminal of the drive target switching element with a charge for turning on or off the drive target switching element (S * #) which is a voltage-controlled switching element;
The charging means includes
A charging path (Lda, Ldb) connected to the open / close control terminal;
An opening / closing element (30a, 30b) provided in the charging path and operated to be turned on and off to open and close the charging path;
Charging speed setting means for switching the setting of the charge speed of the charge to either a high speed or a low speed by changing the operation state of the switching element;
Based on the fact that the temperature of the drive target switching element exceeds the upper limit temperature, the charging means has an abnormality in which the actual charging speed is lower than the charging speed when no abnormality has occurred in the charging means. An abnormality judging means for judging;
When it is determined by the abnormality determining means that an abnormality that causes the charging speed to be low has occurred in the charging means, notification means for notifying information to that effect;
A fail-safe means for performing a predetermined fail-safe process when the notification means informs that there is an abnormality in which the charging speed is low;
An upper limit value of the temperature of the drive target switching element that is higher than the upper limit temperature and can maintain the reliability of the drive target switching element is defined as an allowable temperature,
The fail-safe means determines that the temperature of the drive target switching element reaches the allowable temperature as the fail-safe process when information indicating that the lowering abnormality has occurred is notified by the notification means. The switching element driving device is characterized by performing a process for permitting the driving target switching element to continue to be driven. When it is determined that the temperature of the drive target switching element has reached the allowable temperature, the fail safe means performs a shutdown process for forcibly turning off the drive target switching element as the fail safe process. 8. The driving device for a switching element according to claim 7, wherein: The upper limit temperature is determined when the current flowing between the input / output terminals of the switching element to be driven is an upper limit value that can be taken during normal use of the driving device in a situation where the abnormality does not occur in the charging unit. 9. The switching element driving device according to claim 7 , wherein the temperature of the target switching element is set to an upper limit value that can be taken. A storage means for storing the upper limit temperature;
The storage means stores, as the upper limit temperature, the temperature of the drive target switching element when a current is passed between the input / output terminals of the drive target switching element in an inspection process before shipment of the drive device,
The abnormality determining means determines that an abnormality that causes the charging speed to be lowered is occurring in the charging means based on the temperature of the driving switching element exceeding the upper limit temperature stored in the storage means. The driving device for a switching element according to any one of claims 7 to 9.