JP2008011670A - Inverter system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent thermal damage of switching elements A1, A2, A3, A4, A5, A6, even if currents are caused to flow through the switching elements A1, A2, A3, A4, A5, A6 at electric discharge of a capacitor 12 for smoothing, in an inverter system 10. <P>SOLUTION: A control portion 13 is provided which controls switching of on/off of each of the switching elements A1, A2, A3, A4, A5, A6. The control portion 13 turns on a part of the switching elements, A1, A4, A6, and turns off the rest switching elements A2, A3, A5 while suspending drive of a motor 14 for traveling at the electric discharge. Then after a lapse of predetermined time, the control portion switches to such a state where a part of the switching elements, A1, A4, A6 are turned off, and the rest switching elements A2, A3, A5 are turned on, while suspending drive of the motor 14 for traveling. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inverter device that includes a plurality of switching elements, a smoothing capacitor, and a control unit, and drives a multiphase rotating machine.

  Conventionally, in a vehicle equipped with a traveling motor such as an electric vehicle or a hybrid vehicle, an inverter device has been provided between the traveling motor that is a multi-phase rotating machine and a power supply device. It is known to drive a driving motor by sending a driving signal. FIG. 21 shows an example of a conventional structure of such an inverter device. The inverter device 10 shown in FIG. 21 includes a plurality of switching elements A1, A2, A3, A4, A5, A6 such as an IGBT, a smoothing capacitor 12, and a control unit 13. A plurality of switching elements A1, A2, A3, A4, A5, and A6 are connected to the positive electrode side (upper side in FIG. 21) and the negative electrode side (lower side in FIG. 21) of the power supply device 18, respectively, It is connected to a plurality of phases (U phase, V phase, W phase) windings (not shown) of the traveling motor 14. A protective diode (not shown) is connected in a state adjacent to the plurality of switching elements A1, A2, A3, A4, A5, and A6.

  The smoothing capacitor 12 is connected in parallel with a main circuit section 16 including a plurality of switching elements A1, A2,... A6 and a diode. A main contactor 20 is provided between the positive electrode side of the power supply device 18 and the smoothing capacitor 12. When driving the traveling motor 14 with such an inverter device 10, the traveling motor 14 is controlled by controlling the switching of the switching elements A1, A2,. To drive. Further, when the driving of the traveling motor 14 is stopped, the main contactor 20 is turned off in response to the key switch being turned off by turning off a key switch (not shown). Further, the control unit 13 is provided with a gate circuit 22 for sending a voltage signal to the switching elements A1, A2,... A6.

  In such an inverter device 10, when the power of the control unit 13 is turned off with the electric charge remaining in the smoothing capacitor 12, the input currents of the switching elements A 1, A 2,. The switching elements A1, A2,... A6 and the gate circuit 22 may be damaged. Therefore, when the main contactor 20 is turned off, the smoothing capacitor 12 is discharged in a state in which the driving of the traveling motor 14 is controlled to stop, and at least the switching elements A1, A2,. It has been considered that electric current is supplied to one piece to consume power by heat generated by the resistance of the winding of the traveling motor 14.

  Further, in Patent Document 1, a q-axis current command value, which is a torque current component, is set to 0 in order to discharge an electric charge accumulated in a capacitor when an ignition is turned off. The d-axis current command value is set so that the d-axis current command value, which is the excitation current component, alternately appears positive and negative, and the absolute values thereof are equal.

JP 2005-176580 A

  In the inverter device 10 shown in FIG. 21, if the current continues to flow through some of the switching elements of the inverter device 10 until the smoothing capacitor 12 is completely discharged, the switching elements generate heat and are damaged. Destruction can occur.

  On the other hand, the control device for an electric vehicle described in Patent Document 1 discharges the electric charge accumulated in the capacitor without driving the vehicle at the time of discharging, and prevents the discharge time from becoming long. However, it is not intended to prevent the switching element of the inverter device from being thermally destroyed. In addition, when driving a multi-phase rotating machine such as a motor other than a driving motor with an inverter, current may continue to flow through some switching elements during discharging, as described above, which may cause thermal destruction of the switching elements. is there.

  An object of the present invention is to prevent the switching element from being thermally destroyed even when a current is passed through the switching element during discharging of the smoothing capacitor in the inverter device.

  An inverter device according to the present invention is an inverter device that includes a plurality of switching elements, a smoothing capacitor, and a control unit and drives a multiphase rotating machine, and the control unit drives the multiphase rotating machine. In this case, the multi-phase rotating machine is driven by controlling on / off of a plurality of switching elements, and when the smoothing capacitor is discharged, the driving of the multi-phase rotating machine is stopped and a part of the switching is performed. An inverter device that switches between a state in which an element is turned on and a remaining switching element is turned off and a state in which some switching elements are turned off and a remaining switching element is turned on.

  Preferably, the control unit gradually changes the voltage applied to the switching element when the switching element is turned on and off when discharging.

  More preferably, in the case of discharging, the control unit changes the voltage applied to the switching element at a constant rate of time change when switching the switching element on and off.

  In the inverter device according to the present invention, preferably, the control unit repeatedly switches on and off of the switching element when a predetermined time elapses when discharging.

  Further, the inverter device according to the present invention preferably includes a temperature detection means for detecting the temperature of each switching element, and the controller detects that the temperature detected by the temperature detection means exceeds a predetermined threshold when discharging. In this case, each switching element is switched on and off.

  According to the inverter device of the present invention, even when a current is passed through the switching element when the smoothing capacitor is discharged, the current flows only in a part of the plurality of switching elements in the entire time until the discharge is completed. It is possible to prevent the switching element from continuing and to prevent thermal destruction of the switching element.

[First Embodiment]
Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. 1 to 5 show a first embodiment. The inverter device 10 according to the present embodiment is mounted on a hybrid vehicle or an electric vehicle and used to drive the traveling motor 14 as in the case of the structure shown in FIG. The inverter device 10 has a plurality of switching elements A1, A2, A3, A4 such as IGBTs provided between the power supply device 18 (see FIG. 21) and the traveling motor 14, similarly to the structure shown in FIG. , A5, A6, and protective circuit B1, B2, B3, B4, B5, B6 connected corresponding to the respective switching elements A1, A2, A3, A4, A5, A6. (FIG. 3), a smoothing capacitor 12, and a control unit 13. For example, a permanent magnet type synchronous motor is used as the traveling motor 14.

  The plurality of switching elements A1, A2,... A6 are connected to windings of a plurality of phases (U phase, V phase, W phase) of the traveling motor 14, respectively. The smoothing capacitor 12 is connected in parallel with the main circuit unit 16. A voltage sensor is connected to the smoothing capacitor 12, and a detection signal that is a signal representing a detected value of the voltage of the smoothing capacitor 12 is sent to the control unit 13.

  As shown in FIG. 5, the control unit 13 includes a motor control unit 21, a gate circuit 22, a torque command calculation unit 25, and a vehicle control unit 26. Further, the magnetic pole position of the traveling motor 14 (FIG. 1) is detected by the magnetic pole position sensor 23, the rotation angle of the traveling motor 14 is detected by the rotation sensor 27, and the current of the traveling motor 14 is detected by the current sensor 28. Each detection signal is sent to the motor control means 21. Further, the torque command calculation means 25 generates a torque command corresponding to the accelerator opening, and sends a command signal to the motor control means 21. Moreover, the vehicle control means 26 produces | generates the starting / stopping information of a vehicle based on on / off of a key switch.

  The motor control unit 21 outputs a PWM signal by the PWM signal generation unit 33 based on each detection signal sent from the magnetic pole position sensor 23, the rotation sensor 27, and the current sensor 28 and a command signal from the torque command calculation unit 25. Generated and output to the gate circuit 22. The gate circuit 22 controls switching elements A1, A2,... A6 on / off by selecting switching elements A1, A2,.

  Further, a main contactor 20 (see FIG. 21) is provided between the positive electrode side of the power supply device 18 and the smoothing capacitor 12. The main contactor 20 is turned on and off in conjunction with a key switch (not shown). The main contactor 20 is turned off by the control unit 13 not only when the key switch is turned off but also when a predetermined abnormality occurs in the control unit 13 or the sensor.

  In addition, the motor control unit 21 includes a discharge processing unit 29 that receives a start / stop signal from the vehicle control unit 26. When the discharge processing means 29 confirms the start / stop information and the main contactor 20 being turned off, the discharge processing means 29 sends a predetermined signal to the current command selecting means 30 to turn on / off the switching elements A1, A2,. To control.

  That is, in the case of the present embodiment, when the smoothing capacitor 12 is discharged by turning off the main contactor 20, the driving of the traveling motor 14 is stopped and, as shown in FIG. When A1, A4, A6 are turned on and the remaining switching elements A2, A3, A5 are turned off (S1), some switching elements A1, A4, A6 are turned off and the remaining switching elements A2, A3, A5 are turned on. The state to be turned on (S2) is switched.

  Specifically, first, immediately after the start of discharge, as step S1 shown in FIGS. 2 and 4, the switching elements A1, A4, A6 are turned on while the driving of the traveling motor 14 is stopped, and the switching elements A2, A3, A3 are turned on. Turn off A5. Thereby, as shown in FIG. 1, among the switching elements A1, A2,... A6, a current flows only in the switching elements A1, A4, A6. Then, current flows through the windings of a plurality of phases (U phase, V phase, W phase) in directions indicated by arrows A, B, and C in FIG.

  Next, after a predetermined time has elapsed, as step S2 shown in FIGS. 2 and 4, the switching elements A1, A4, A6 are turned off while the driving of the traveling motor 14 is stopped, and the switching elements A2, A3, A3 are turned off. Turn on A5. Thereby, as shown in FIG. 3, among the switching elements A1, A2,... A6, a current flows only in the switching elements A2, A3, A5. Then, current flows through the windings of a plurality of phases (U-phase, V-phase, W-phase) in the directions indicated by arrows a, b, c in FIG. Electricity is consumed. Next, in step S3, all switching operations are performed on condition that it is determined that a total time T, which is a total elapsed time from the start of discharge, is a discharge completion time, and that a time corresponding to the discharge completion obtained in advance has elapsed. The elements A1, A2,... A6 are turned off and the process ends.

  According to this embodiment, even when a current is passed through the switching elements A1, A2,... A6 when the smoothing capacitor 12 is discharged, a part of the plurality of switching elements is consumed in the entire time until the discharge is completed. Can be prevented from continuing to flow through only the same switching elements A1, A2,... A6, and thermal destruction of the switching elements A1, A2,.

  Note that the switching elements A1, A2,... A6 can be turned on and off in steps S1 and S2 with respect to the case of the present embodiment. That is, in step S1, the driving of the traveling motor 14 is stopped, the switching elements A1, A4, A6 are turned off, the switching elements A2, A3, A5 are turned on, and then in step S2, the traveling motor 14 is turned on. The switching elements A1, A4, and A6 can be turned on and the switching elements A2, A3, and A5 can be turned off while stopping the driving.

[Second Embodiment]
Next, FIGS. 6 to 8 show a second embodiment of the present invention. In the case of the present embodiment, the combinations of the switching elements A1, A2,... A6 that are turned on or off at the same time are different from those in the case of the first embodiment. That is, in the case of the present embodiment, first, as step S1 shown in FIG. 8, immediately after the start of discharge, the driving of the traveling motor 14 is stopped, and the switching elements A2, A3, A6 are turned on. Turn off A1, A4 and A5. Thereby, as shown in FIG. 6, among the switching elements A1, A2,... A6, a current flows only in the switching elements A2, A3, A6. Then, current flows through the windings of a plurality of phases (U phase, V phase, W phase) in the directions indicated by arrows A, B, and C in FIG.

Next, as step S2 shown in FIG. 8, after a predetermined time has elapsed, the driving of the traveling motor 14 is stopped, the switching elements A2, A3, A6 are turned off, and the switching elements A1, A4, A5 are turned off. Turn on. Thereby, as shown in FIG. 7, among the switching elements A1, A2,... A6, a current flows only in the switching elements A1, A4, A5. Then, currents flow through the windings of a plurality of phases (U-phase, V-phase, W-phase) in the directions indicated by arrows a, b, c in FIG. 7, that is, in the direction opposite to the direction shown in FIG. Electricity is consumed. Next, in step S3 (see FIG. 2), if the time after the start of discharge, which is the total time T, has elapsed until the time corresponding to the discharge completion obtained in advance, which is the discharge completion time, all The switching elements A1, A2,... A6 are turned off and the process ends.
Other configurations and operations are the same as those in the first embodiment.

[Third Embodiment]
Next, FIGS. 9 to 11 show a third embodiment of the present invention. In the case of the present embodiment, the combinations of switching elements that are turned on or off at the same time are different from those of the first embodiment and the second embodiment. That is, in the case of the present embodiment, first, as step S1 shown in FIG. 11, immediately after the start of discharge, the driving of the traveling motor 14 is stopped and the switching elements A2, A4, A5 are turned on, and the switching element A1 is turned on. , A3, A6 are turned off. Thereby, as shown in FIG. 9, among the switching elements A1, A2,... A6, a current flows only in the switching elements A2, A4, A5. Then, current flows through the windings of a plurality of phases (U phase, V phase, W phase) in directions indicated by arrows A, B, and C in FIG. 9, and power is consumed.

  Next, as step S2 shown in FIG. 11, after a predetermined time has elapsed, the driving of the traveling motor 14 is stopped, the switching elements A2, A4, A5 are turned off, and the switching elements A1, A3, A6 are turned off. Turn on. Thereby, as shown in FIG. 10, among the switching elements A1, A2,... A6, a current flows only in the switching elements A1, A3, A6. Then, currents flow through the windings of a plurality of phases (U-phase, V-phase, W-phase) in the directions indicated by arrows a, b, c in FIG. Electricity is consumed.

Next, in step S3 (see FIG. 2), if the time after the start of discharge, which is the total time T, has elapsed until the time corresponding to the discharge completion obtained in advance, which is the discharge completion time, all The switching elements A1, A2,... A6 are turned off and the process ends.
Other configurations and operations are the same as those in the first embodiment shown in FIGS.
The combination of the switching elements A1, A2,... A6 through which current flows is not limited to the case of the first to third embodiments, but in each of the above embodiments Explained three examples of conditions that are more severe from the viewpoint of durability of the switching element, in which a current may flow through only one switching element on the positive electrode side or the negative electrode side. Even in this case, it is possible to prevent thermal destruction of the switching elements A1, A2,... A6 by switching the switching elements A1, A2,.

[Fourth Embodiment]
Next, FIGS. 12 to 14 show a fourth embodiment of the present invention. In the case of the present embodiment, in the first embodiment shown in FIGS. 1 to 5, the switching elements A1, A2,... A6 are turned on / off in the case of moving from step S1 to S2 in FIG. At the time of switching, the voltage applied to (applied to) the switching elements A1, A2,... A6 by the gate circuit 22 (see FIG. 1) while stopping the driving of the traveling motor 14 is set at a constant time change rate K (or -K) is gradually changed. Here, K is a positive value. That is, at the time of transition from step S1 to S2, the voltage represented by the voltage signal sent from the gate circuit 22 to the switching elements A1, A2,... A6 is gradually changed at a constant time change rate K (or -K). Yes.

  In order to switch the switching elements A1, A2,... A6 on and off, for example, during discharge, the discharge processing means 29 (see FIG. 5) changes the current command selection means 30 (see FIG. 5) Of the current applied to the motor 14 (see FIG. 1), a q-axis current command value that is a torque current component and a d-axis current command value that is an excitation current component are sent. Then, as shown in FIG. 14, immediately after the start of discharge, the q-axis current command value is set to 0A, the d-axis current command value is set to -X, which is a negative value, and then after a predetermined time has elapsed. While the q-axis current command value is kept at 0 A, the d-axis current command value is gradually increased linearly at a constant time change rate P, and is switched to a positive value X. Note that -X and X have the same absolute value.

  The q-axis current command value and the d-axis current command value are sent to the current control means 31 (see FIG. 5) together with the q-axis current and the d-axis current based on the current value detected by the current sensor 28 (see FIG. 5). Thus, the current control means 31 calculates the q-axis voltage command value and the d-axis voltage command value. The calculated d-axis voltage command value and q-axis voltage command value, together with the rotational phase of the traveling motor 14 calculated by the phase calculation means 34 (see FIG. 5), are converted into the two-phase / three-phase conversion means 32 (see FIG. 5). ) And converted into a three-phase AC voltage command value, and then sent to the PWM signal generation means 33 (see FIG. 5). The PWM signal generation unit 33 generates a PWM signal based on the three-phase AC voltage command value and the triangular wave signal (carrier signal), and sends the PWM signal to the gate circuit 22 (see FIGS. 1 and 5). Based on the PWM signal, the gate circuit 22 selects and sends voltage signals to the switching elements A1, A2,... A6, and switches the switching elements A1, A2,. .

In such a configuration, since the q-axis current command value to be set is set to 0 A during discharging, the driving of the traveling motor 14 can be stopped. Further, since the d-axis current command value is switched from −X having the same absolute value to X at the time of discharge, it is possible to prevent the current from continuing to flow through some of the same switching elements until the discharge is completed. For example, even when the switching elements A1, A4, A6 are turned on and the switching elements A2, A3, A5 are turned off immediately after discharging as in the present embodiment, the switching element A1 after a predetermined time has elapsed. , A4, A6 can be turned off and the switching elements A2, A3, A5 can be turned on. In the case of the present embodiment, as shown in FIG. 13, the voltage represented by the voltage signal sent from the gate circuit 22 (see FIG. 1) to the switching elements A1, A2... A6 (see FIG. 1 etc.). Is gradually changed at a constant time change rate K (or -K). For this reason, switching control of on / off of switching element A1, A2 ... A6 can be performed more stably.
Other configurations and operations are the same as those of the first embodiment shown in FIGS. 1 to 5 described above, and thus redundant description is omitted.

[Fifth Embodiment]
Next, FIGS. 15 to 16 show a fifth embodiment of the present invention. In the case of the present embodiment, it is possible to switch the switching elements A1, A2,... A6 on and off a plurality of times (four times in the case shown in FIG. 17) between the start of discharge and the completion of discharge. Yes. That is, in this embodiment, immediately after the start of discharge, first, in step S1, the switching elements A1, A4, and A6 are turned on as in the fourth embodiment shown in FIGS. The switching elements A2, A3 and A5 are turned off. Next, on the condition that the predetermined time t has elapsed, the control unit 13 (see FIG. 1) determines whether or not the total time T that is the total elapsed time from the start of discharge has passed the discharge completion time. If it is determined by this determination that the total time T has passed the discharge completion time, all the switching elements A1, A2,.

  On the other hand, if it is determined that the discharge completion time has not elapsed, the switching elements A1, A4, A6 are turned off and the switching elements A2, A3, A5 are turned off in step S2, as shown in FIG. It is gradually changed to a constant time change rate K (or -K), and the state is maintained. Next, on the condition that the predetermined time t has elapsed, it is determined whether or not the total time T has passed the discharge completion time. If it is determined that the discharge completion time has passed, all the switching elements A1, A2,... A6 are turned off and the process ends.

  In this case, if it is determined that the discharge completion time has not elapsed, the switching elements A1, A4, A6 are turned on and the switching elements A2, A3, A5 are turned off for a certain time in step S3. The rate of change is gradually changed at −K (or K), and the state is maintained. Next, on the condition that the predetermined time t has elapsed, it is determined whether or not the total time T has passed the discharge completion time. If it is determined that the discharge completion time has passed, all the switching elements A1, A2,... A6 are turned off and the process ends. Also, in this determination, if it is determined that the discharge completion time has not elapsed, the process returns to step S2, and thereafter, step S2 and step S3 are performed, and the total time T is determined after step S2 (or S3) ends. Repeat until it is determined that the discharge completion time has elapsed.

  In order to switch the switching elements A1, A2,... A6 on and off, for example, as in the fourth embodiment shown in FIGS. The q-axis current command value and the d-axis current command value sent from the current command selection means 30 (see FIG. 5) to the current command selection means 30 (see FIG. 5) are set. That is, as shown in FIG. 17, at the time of discharging, in step S1, the q-axis current command value is set to 0A, and the d-axis current command value is set to -X, which is a negative value. Next, on the condition that it is determined that the total time T has not passed the discharge completion time after the elapse of t time from the start of discharge, the d-axis current command value is changed from a negative value -X to a positive value in step S2. Switch to X which is the value of. Further, at the time of switching, the d-axis current command value is gradually increased linearly at a constant time change rate P.

  Further, in step S3, the d-axis current command value is set on condition that it is determined that the total time T has not passed the discharge completion time after elapse of t time from the time when the d-axis current command value becomes X. Switching from a positive value X to a negative value -X, and at the time of this switching, the d-axis current command value is gradually decreased at a constant rate of time change -P. Thereafter, step S2 and step S3 are repeated until it is determined that the total time T has passed the discharge completion time after the end of step S2 (or S3) (that is, after elapse of time t).

According to the present embodiment, when the smoothing capacitor 12 is discharged by shortening the time t for performing steps S1, S2, and S3, the same switching elements A1, A2,. Only when the current continues to flow can be shortened, and thermal destruction of the switching elements A1, A2,... A6 can be more effectively prevented.
Other configurations and operations are the same as those in the fourth embodiment shown in FIGS. 12 to 14 described above, and thus redundant description is omitted.

[Sixth Embodiment]
Next, FIGS. 18 to 20 show a sixth embodiment of the present invention. In the case of the present embodiment, in the fifth embodiment shown in FIGS. 15 to 17, the temperature sensors 24a, 24b, A total of six 24c, 24d, 24e, and 24f are installed one by one. In addition, only one temperature sensor can be installed in a portion where the temperature is most likely to rise among all the switching elements A1, A2,... A6, and the temperature can be monitored. In the case of the present embodiment, the conditions for determining the end of each of step S1, step S2, and step S3 are detected by the temperature sensors 24a, 24b,. The condition is that one of the detected temperatures in the vicinity of each of the switching elements A1, A2,... A6 exceeds a predetermined threshold value. This threshold value is set in advance, may be a temperature that the switching elements A 1, A 2,... A 6 can sufficiently withstand in use, and may be determined based on a heat resistant standard temperature of the inverter device 10. A signal indicating the detected temperature detected by the temperature sensors 24a, 24b,..., 24f is sent to the control unit 13 (see FIGS. 1 and 5), and the control unit 13 determines whether any of the detected temperatures exceeds a threshold value. I do. If it is determined that any of the detected temperatures exceeds the threshold value, it is determined whether or not the discharge completion time has elapsed, and on the condition that it has been determined that the discharge completion time has not elapsed, the switching element A1, A2,... A6 are switched on / off.

  For example, in step S1 shown in FIG. 19, the switching elements A1, A4, A6 are turned on, and the switching elements A2, A3, A5 are turned off. Next, the control unit 13 determines whether any of the detected temperatures exceeds the threshold value. If it is determined that the detected temperature exceeds the threshold value, the total time T that is the total elapsed time from the start of discharge is the discharge completion time. It is determined whether or not elapses. If it is determined by this determination that the discharge completion time has elapsed, all the switching elements A1, A2,... A6 are turned off and the process ends. On the other hand, if it is determined that the discharge completion time has not elapsed, the switching elements A1, A4, A6 are turned off, the switching elements A2, A3, A5 are turned on, and the gate circuit 22 in step S2. Are switched so that the voltage represented by the voltage signal sent to each of the switching elements A1, A2,... A6 gradually changes at a constant time change rate K (−K), and the state is maintained.

  In order to switch such switching elements A1, A2,... A6 on and off, for example, as in the fourth embodiment shown in FIGS. The q-axis current command value and the d-axis current command value sent from the current command selection means 30 (see FIG. 5) from (see FIG. 5) are set. That is, as shown in FIG. 20, at the time of discharging, in step S1, the q-axis current command value is set to 0A, and the d-axis current command value is set to -X, which is a negative value. Next, if it is determined that any of the detected temperatures detected by the temperature sensors 24a, 24b,..., 24f exceeds the threshold value, the total time T, which is the total elapsed time from the start of discharge, has passed the discharge completion time. In step S2, the d-axis current command value is switched from a negative value -X to a positive value X on the condition that it is determined that there is no. Further, at the time of this switching, the d-axis current command value is gradually increased at a constant time change rate P.

  In this case, as the d-axis current command value is switched from −X to X, the maximum value of each detected temperature, which is the highest temperature detected by the temperature sensors 24a, 24b,. This is because switching elements A1, A2,... A6 through which current flows by switching between positive and negative d-axis current command values are switched from switching elements A1, A4, A6 to switching elements A2, A3, A5.

  If the d-axis current command value continues to be X, the current continues to flow through some of the switching elements A2, A3, A5. Therefore, any temperature set in the vicinity of some of the switching elements A2, A3, A5 The detection temperature of the sensor rises. As a result, the maximum value of each detected temperature rises again, but it is determined that the detected temperature of one of the temperature sensors has exceeded the threshold value, and the total time T has been determined not to have passed the discharge completion time. In step S3, the d-axis current command value is switched from a positive value X to a negative value -X. Further, at the time of this switching, the d-axis current command value is gradually decreased at a constant time change rate −P. Thereafter, Step S2 and Step S3 are repeated until Step S2 (or S3) ends (that is, after any detected temperature exceeds a threshold) until the total time T has passed the discharge completion time.

According to the present embodiment as described above, whether or not any of the detected temperatures detected by the temperature sensors 24a, 24b,..., 24f detected by the temperature sensors 24a, 24b,. Therefore, the thermal destruction of the switching elements A1, A2,... A6 can be more effectively prevented as compared with the case where a certain time has passed.
Other configurations and operations are the same as those of the fifth embodiment shown in FIGS. 15 to 17 described above, and thus redundant description is omitted.

  In the above description, the case where the number of switching elements A1, A2,... A6 is six has been described, but the present invention can also be implemented with a structure provided with switching elements other than six.

In the inverter apparatus according to the embodiment of the first invention, it is a schematic configuration diagram for explaining a switching element through which a current flows in step S1. It is a figure which similarly shows the flowchart after discharge start. FIG. 5 is a schematic configuration diagram omitting a part for explaining a switching element through which a current flows in step S2. Similarly, in steps S1 and S2, it is a diagram for explaining a change in voltage applied from the gate circuit to the switching element. It is a block diagram which shows the control part of FIG. 1 in detail. In the inverter device according to the second embodiment of the present invention, it is a schematic configuration diagram in which a part for explaining a switching element through which a current flows in step S1 is omitted. FIG. 5 is a schematic configuration diagram omitting a part for explaining a switching element through which a current flows in step S2. It is a figure corresponding to FIG. 4 similarly. In the inverter apparatus of 3rd invention embodiment, it is the schematic block diagram which abbreviate | omitted one part for demonstrating the switching element through which an electric current flows by step S1. FIG. 5 is a schematic configuration diagram omitting a part for explaining a switching element through which a current flows in step S2. It is a figure corresponding to FIG. 4 similarly. In the inverter apparatus of embodiment of 4th invention, it is a figure which shows the flowchart after discharge start. It is a figure corresponding to FIG. 4 similarly. It is a figure which similarly shows the change of the setting value of d-axis current command value and q-axis current command value after the start of discharge. In the inverter apparatus of 5th Embodiment, it is a figure which shows the flowchart after discharge start. Similarly, in steps S1, S2 and S3, it is a diagram for explaining a change in voltage applied from the gate circuit to the switching element. It is a figure which similarly shows the change of the setting value of d-axis current command value and q-axis current command value after the start of discharge. In the inverter apparatus of embodiment of 6th invention, it is a schematic block diagram which shows the connection state of each switching element and a motor winding, and the installation state of a temperature sensor. It is a figure which similarly shows the flowchart after discharge start. It is a figure which similarly shows the setting value of d-axis current command value and q-axis current command value after a discharge start, and the change of the maximum value of each detection temperature. It is a schematic block diagram of an example of the conventional structure which provided the inverter apparatus between the motor for driving | running | working and the power supply device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Inverter apparatus, 12 Smoothing capacitor, 13 Control part, 14 Traveling motor, 16 Main circuit part, 18 Power supply device, 20 Main contactor, 21 Motor control means, 22 Gate circuit, 23 Magnetic pole position sensor, 24a, 24b, 24c, 24d, 24e, 24f Temperature sensor, 25 Torque command calculation means, 26 Vehicle control means, 27 Rotation sensor, 28 Current sensor, 29 Discharge processing means, 30 Current command selection means, 31 Current control means, 32 2-phase / 3 Phase conversion means, 33 PWM signal generation means, 34 phase calculation means.

Claims (5)

  An inverter device that includes a plurality of switching elements, a smoothing capacitor, and a control unit, and drives the multi-phase rotating machine, wherein the control unit drives the multi-phase rotating machine. When the multi-phase rotating machine is driven by controlling on / off of the motor and the smoothing capacitor is discharged, the driving of the multi-phase rotating machine is stopped, and a part of the switching elements are turned on, and the remaining switching elements An inverter device that switches between a state in which the switch is turned off and a state in which some of the switching elements are turned off and the remaining switching elements are turned on.   The inverter device according to claim 1, wherein the control unit gradually changes a voltage applied to the switching element when switching the switching element between on and off when discharging.   3. The inverter device according to claim 2, wherein the control unit changes the voltage applied to the switching element at a constant rate of time change when switching the switching element on and off when discharging. Inverter device.   4. The inverter device according to claim 1, wherein the control unit repeatedly switches on and off of the switching element when a predetermined time elapses when discharging. Inverter device.   The inverter device according to any one of claims 1 to 3, further comprising temperature detecting means for detecting a temperature of each switching element, wherein the controller detects the temperature detected by the temperature detecting means when discharging. An inverter device that switches on and off each switching element when a predetermined threshold value is exceeded.

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