JP2015032984A - Device for driving semiconductor element, and power conversion device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for driving a semiconductor element and a power conversion device therewith which reliably protect a semiconductor switching element from a short circuit current.SOLUTION: A protection circuit provided in the device for driving a semiconductor switching element includes: a short circuit detection section 102 for detecting a short circuit on the basis of a main current flowing through an IGBT 24 and a gate voltage of the IGBT 24, and outputting a short circuit detection signal if detecting a short circuit; a short circuit di/dt control section 106 for reducing di/dt of a short circuit current if detecting a short circuit on the basis of the main current flowing through the IGBT 24; and a drive interruption section 104 for sending an interruption command signal to a drive section 105 on the basis of the short circuit detection signal. The drive section 105 turns off the IGBT 24 on the basis of the interruption command signal after di/dt of the short circuit current is reduced.

Description

  The present invention relates to a semiconductor device driving apparatus and a power conversion apparatus using the same.

  The power converter is a function for converting DC power supplied from a DC power source into AC power for supplying an AC electric load such as a rotating electrical machine, or for supplying AC power generated by the rotating electrical machine to a DC power source. It has a function to convert to DC power. In order to perform the conversion function, the power conversion device includes an inverter circuit having a plurality of semiconductor switching elements, and the semiconductor switching element repeats a conduction operation and a cutoff operation, thereby switching from DC power to AC power or from AC power to DC. Power conversion to power is performed.

  In order to prevent a failure of the power conversion device in the event of an abnormality such as a power supply short circuit, the semiconductor switching element driving device has a protection function for preventing the semiconductor switching element from being destroyed by an excessive current flowing during the short circuit. As a conventional technique related to such a protection function, a technique described in Patent Document 1 is known. In this technique, when a short-circuit current is detected by a sense IGBT of an insulated gate bipolar transistor (hereinafter referred to as IGBT) with a current sense, the gate is shut off after a predetermined delay time to prevent false detection. To turn off.

Japanese Patent Laid-Open No. 3-40517

  If the turn-on drive of the semiconductor switching element is speeded up in order to reduce the loss of the power conversion device, the short-circuit current sharply increases, and the short-circuit current may oscillate, causing the element to fail. On the other hand, the prior art detects the magnitude of the short-circuit current and does not take into account a transient increase in the short-circuit current, so that it is difficult to prevent device failure. Moreover, in the said prior art, since the operation delay time for preventing erroneous detection is set, the time for which the short-circuit current flows becomes long, and it is difficult to reliably protect the element from the short-circuit current.

  Therefore, the present invention provides a driving device for a semiconductor element that reliably protects the semiconductor switching element from a short-circuit current, and a power converter using the same.

  In order to solve the above problems, a semiconductor device driving apparatus according to the present invention generates a driving signal for controlling on / off of a semiconductor switching element, and applies the driving signal to a control electrode of the semiconductor switching element. And a protection circuit for protecting the semiconductor switching element from a short-circuit current, the protection circuit short-circuiting based on a main current flowing through the semiconductor switching element and a control voltage of the semiconductor switching element. Detecting a short circuit and outputting a short circuit detection signal when a short circuit is detected, a short circuit di / dt controller for reducing a short circuit current di / dt when detecting a short circuit based on the main current, and the short circuit detection signal And a drive cutoff unit that transmits a cutoff command signal to the drive unit based on the short-circuit di / dt control unit. After reducing the current di / dt, turning off the semiconductor switching element based on the interruption command signal.

  In addition, it may replace with the said main current and may detect a short circuit using the voltage between main electrodes of a semiconductor switching element.

  The power converter according to the present invention includes an arm circuit in which both ends of a series circuit of a semiconductor switching element on the upper arm side and a semiconductor switching element on the lower arm side are connected to a DC power source, and a series connection point is connected to an AC terminal. And a plurality of drive circuit devices for controlling on / off of the semiconductor switching element on the upper arm side and the semiconductor switching element on the lower arm side. The semiconductor device driving apparatus according to the present invention is used.

  According to the driving device of the present invention, the semiconductor switching element can be reliably protected from the short-circuit current. In addition, the power conversion device using the driving device according to the present invention is less likely to fail even when an overcurrent flows, and thus the reliability is improved.

  Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

The circuit structure by the side of the lower arm containing the drive device which is one Example of this invention is shown. A specific example of the circuit configuration of this embodiment will be shown. An example of a conventional operation waveform is shown. An operation waveform example of this embodiment is shown. Another embodiment of the present invention will be described. The specific example of the circuit structure of the other Example of this invention is shown. The circuit structure of the inverter apparatus of a present Example is shown.

  Embodiments of the present invention will be described below with reference to the drawings.

  The configuration described below can also be applied to a DC-DC power converter such as a DC / DC converter or a DC chopper. Moreover, the structure demonstrated below is applicable also to power converters, such as vehicle-mounted use, industrial use, and household use.

  First, an electrical circuit configuration of an inverter device according to an embodiment of the present invention will be described with reference to FIG.

  The inverter device INV of the present embodiment includes a power module PMU, a drive circuit device DCU, and an electric motor control unit MCU. The power module PMU constitutes a main circuit for power conversion, operates in response to a drive signal output from the drive circuit unit DCU, and converts DC power supplied from the high-voltage battery BAT, which is a DC power supply, into three-phase AC power. And supplied to the stator winding of the motor M. The main circuit is a three-phase bridge circuit, and a series circuit (Au, Av, Aw) for three phases is electrically connected in parallel between the positive electrode side and the negative electrode side of the high voltage battery BAT. The series circuit is also called an arm and is constituted by two power semiconductor switching elements.

  The arm is configured by electrically connecting a power semiconductor switching element on the upper arm side and a power semiconductor switching element on the lower arm side in series. In this embodiment, an IGBT (insulated gate bipolar transistor) is used as the power semiconductor switching element. In the IGBT, a diode element is electrically connected in reverse parallel between the collector electrode and the emitter electrode. Further, the IGBT includes a gate electrode in addition to the collector electrode and the emitter electrode.

  As the power semiconductor switching element, another voltage control type semiconductor switching element, for example, an n-channel MOSFET (metal / oxide / semiconductor field effect transistor) may be used. A semiconductor chip constituting the MOSFET includes three electrodes, a drain electrode, a source electrode, and a gate electrode. In addition, a parasitic built-in diode whose forward direction is from the source electrode to the drain electrode is electrically connected in reverse parallel between the drain electrode and the source electrode.

  The U-phase arm Au is configured by electrically connecting an emitter electrode of the power semiconductor switching element Mpu on the upper arm side and a collector electrode of the power semiconductor switching element Mnu on the lower arm side. In FIG. 7, the specific circuit configuration is shown only in the block showing the U-phase arm Au, but the V-phase arm Av and the W-phase arm Aw are the same as the U-phase arm Au, and the power semiconductor switching element Mpv , Mpw emitter electrodes and power semiconductor switching elements Mnv, Mnw collector electrodes are electrically connected in series, respectively. In the text, the subscripts p and n indicate the upper arm and the lower arm, respectively, and the subscripts u, v, and w indicate the U phase, V phase, and W phase of three-phase alternating current, respectively.

  The collector electrodes of the power semiconductor switching elements Mpu, Mpv, Mpw are electrically connected to the high potential side (positive electrode side) of the high voltage battery BAT. The emitter electrodes of the power semiconductor switching elements Mnu, Mnv, Mnw are electrically connected to the low potential side (negative electrode side) of the high voltage battery BAT. Further, the collector of the power semiconductor switching element (Mpu, Mpv, Mpw, Mnu, Mnv, Mnw) and the cathode of the diode element (Dpu, Dpv, Dpw, Dnu, Dnv, Dnw) are electrically connected, and the power semiconductor switching element The emitter of (Mpu, Mpv, Mpw, Mnu, Mnv, Mnw) and the anode of the diode element (Dpu, Dpv, Dpw, Dnu, Dnv, Dnw) are electrically connected.

  The middle point of the U-phase arm Au, that is, the connecting portion between the emitter electrode of the upper power semiconductor switching element and the collector electrode of the lower power semiconductor switching element is electrically connected to the U-phase stator winding of the motor M. Connected. Similarly to the midpoint of the U-phase arm Au, the midpoint of the V-phase arm Av and the W-phase arm Aw is electrically connected to the V-phase and W-phase stator windings of the motor M, respectively.

  A smoothing electrolytic capacitor SEC is electrically connected between the positive electrode side and the negative electrode side of the high-voltage battery BAT, which is a DC power source, in order to suppress fluctuations in DC voltage caused by the operation of the power semiconductor switching element. Yes.

  In the power module PMU, a semiconductor chip is mounted on a base surrounded by a case via an insulating substrate so that a three-phase bridge circuit is formed. Between the semiconductor chips, between the semiconductor chip and the input terminal, the semiconductor chip And the output terminal are electrically connected by a connection conductor such as an aluminum wire or a plate-like conductor. The base is made of a heat conductive member such as copper or aluminum. The lower surface of the base is cooled by a cooling medium such as air or cooling water. Fins and the like are provided on the lower surface of the base in order to improve the cooling efficiency by the cooling medium. The insulating substrate is made of an insulating member such as aluminum nitride, and wiring patterns are metallized on both sides. The semiconductor chip constitutes the above-described IGBT and diode element, and has electrodes on both sides. The base and the insulating substrate, and the insulating substrate and the semiconductor chip are joined by a joining member such as solder.

  The drive circuit unit DCU is electrically connected to the gate electrode of the power semiconductor switching element (Mpu, Mpv, Mpw, Mnu, Mnv, Mnw). The drive circuit unit DCU receives and receives the control command signals (Vpu *, Vpv *, Vpw *) of the upper arm side power semiconductor switching elements (Mpu, Mpv, Mpw *) output from the motor control unit MCU. In response to the command signals (Vpu *, Vpv *, Vpw *), drive signals (Vpu, Vpv, Vpw) for turning on / off the power semiconductor switching elements (Mpu, Mpv, Mpw) on the upper arm side are created. Then, it is output to the gate electrode of the power semiconductor switching element (Mpu, Mpv, Mpw) on the upper arm side. The drive circuit unit DCU receives and receives control command signals (Vnu *, Vnv *, Vnw *) of the power semiconductor switching elements (Mnu, Mnv, Mnw) on the lower arm side output from the motor control unit MCU. In response to the control command signals (Vnu *, Vnv *, Vnw *), the drive signals (Vnu, Vnv, Vnw) for driving the power semiconductor switching elements (Mnu, Mnv, Mnw) on the lower arm side on and off Is output to the gate electrode of the power semiconductor switching element (Mnu, Mnv, Mnw) on the lower arm side.

  The drive circuit unit DCU includes as many semiconductor element drive devices (see FIGS. 1, 2, 5, and 6) as the embodiments of the present invention described later, as many as the number of power semiconductor switching elements, in FIG. I have. These driving devices include a protection circuit that protects the power semiconductor switching element from a short-circuit current. The protection circuit includes a main current of the power semiconductor switching element (for example, IGBT collector current) or a voltage between the main electrodes (for example, IGBT collector-emitter voltage) and a control voltage of the power semiconductor switching element (for example, IGBT gate-emitter On the basis of the voltage between the emitters), the current rise rate di / dt of the short-circuit current is reduced from the normal time, and then the power semiconductor switching element is turned off. As a result, the power semiconductor switching element can be reliably protected from the short-circuit current, so that the reliability of the power conversion device is improved.

  The motor control unit MCU calculates a control value for operating the power semiconductor switching element of the power module PMU based on a plurality of input signals that have been input, and calculates the calculated control value as a control command signal (Vpu * to Vnw). *) Is output to the drive circuit unit DCU, and includes a microcomputer for calculating the control value. The microcomputer has as input signals a torque command signal (torque command value) τ *, a rotation speed command signal (rotation speed command value) n *, detection signals (current values of U phase to W phase) iu to iw, and detection. A signal (magnetic pole position of the rotor) θ is input. The torque command signal (torque command value) τ * and the rotation speed command signal (rotation speed command value) n * are output from a general controller GCU (not shown) according to the operation mode. Detection signals (current values from U phase to W phase) iu to iw are output from current sensors Cu to Cw. The detection signal (magnetic pole position of the rotor) θ is output from a magnetic pole position sensor attached to the motor M.

  The current sensors Cu to Cw are for detecting the U-phase to W-phase currents iu to iw supplied from the inverter device INV (that is, the power module PMU) to the stator winding of the stator of the motor M, and are shunted. It consists of resistors, current transformers (CT), etc. The magnetic pole position sensor is for detecting the magnetic pole position θ of the rotor of the motor M, and includes a resolver, an encoder, a Hall element, a Hall IC, and the like.

  The microcomputer calculates the current command values (Id *, Iq *) for the d-axis and the q-axis based on the input signal, and the voltage control value (Vu) based on the calculated current command values (Id *, Iq *). To Vw), and the calculated voltage control value (Vu to Vw) is used as a control command signal (for example, PWM signal (pulse width modulation signal)) Vpu * for operating the power semiconductor switching element of the power module PMU. ~ Vnw * is output to the drive circuit unit DCU.

  Next, a semiconductor device driving apparatus according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a circuit configuration including a power semiconductor switching element on the lower arm side of an arm for one phase and its driving device in the power module PMU in FIG. The circuit configuration on the upper arm side is the same.

  A diode element 25 is electrically connected in parallel with the switching element IGBT 24, and the IGBT 24 includes a current sensing IGBT 100 for detecting a main current. For example, a sense current that is one thousandth of the main current flows through the current sense IGBT 100, and this sense current is converted into a sense voltage by the sense resistor 101 that is electrically connected to the emitter electrode of the current sense IGBT 100. .

  The sense voltage and the gate voltage of the IGBT 24 are input to the high-speed short circuit detection unit 102. The high-speed short-circuit detection unit 102 outputs a short-circuit detection signal when the sense voltage and the gate voltage of the IGBT 24 exceed a predetermined threshold value. In this way, the short-circuit current can be reliably detected by detecting the gate voltage in addition to the sense voltage, that is, the main current flowing through the IGBT 24. For this reason, the detection of the short circuit current can be speeded up, for example, it is not necessary to set an operation delay time for preventing erroneous detection.

  When the short-circuit di / dt control unit 106 receives the sense voltage and determines that the input sense voltage exceeds a predetermined threshold, the IGBT 24 is turned on more slowly than the normal turn-on, and the current increase rate of the short-circuit current di / dt Reduce. As a result, it is possible to prevent the short-circuit current from being vibrated due to the steep rise of the short-circuit current.

  When receiving the short circuit detection signal, the drive cutoff unit 104 transmits a cutoff signal to the drive unit 105 that drives the IGBT 24 on and off. The drive shut-off unit 104 receives an abnormal state detection signal (not shown) such as when the gate power supply (Vcc) of the IGBT 24 drops below a predetermined voltage or when the IGBT 24 exceeds a predetermined temperature. The driver 105 may have a function of transmitting a cutoff signal.

  When the drive unit 105 receives a control command signal (for example, Vnu *) sent from the host motor control unit MCU in a normal state, the drive unit 105 gives a drive signal for turning on / off the IGBT 24 to the gate electrode of the IGBT 24. The motor control unit MCU side that transmits the control command signal and the drive unit 105 side that receives this signal may be electrically insulated by a photocoupler or the like. Based on the signal indicating the operation state of the short-circuit di / dt control unit 106 and the cut-off signal from the drive cut-off unit 104, the short-circuit di / dt control unit 106 reduces the short-circuit current di / dt. Thereafter, the IGBT 24 is turned off. The drive unit 105 in this embodiment has a soft shut-off function that turns off the IGBT 24 more slowly than normal turn-off. This function can suppress an excessive jump voltage (surge voltage) when the short-circuit current is turned off.

  FIG. 2 shows a specific example of the circuit configuration of this embodiment.

  The comparator 201 receives the sense voltage of the sense resistor 101, and outputs a first detection signal (for example, a High signal) when the input sense voltage exceeds a first predetermined threshold value Vic1. The threshold value Vic1 is a reference voltage that is set based on the sense ratio and sense resistance of the sense IGBT 100 with respect to a current that is several times the rated current of the IGBT 24, for example, a resistance voltage division from a highly accurate reference power source such as a band gap reference, etc. Created with. The comparator 212 receives the gate voltage of the IGBT 24, and outputs a second detection signal (for example, a High signal) when the input gate voltage exceeds a second predetermined threshold Vic2. The threshold value Vic2 is set to a high level gate voltage Vg1 (see FIG. 4) of the IGBT 24, that is, a voltage higher than the gate-emitter voltage in a normal state.

  When a short-circuit current flows, the collector voltage (Vce) of the IGBT 24 falls for a moment and rises further (see FIG. 4). Thus, current flows into the gate of the IGBT 24 due to dv / dt when the collector voltage increases and the feedback capacitance of the IGBT 24, and the gate voltage rises from Vg1. Using this phenomenon, the comparator 212 detects a short circuit. The logic unit 213 receives the first detection signal and the second detection signal, and outputs a first short circuit detection signal (High signal) when both are High.

  In the short-circuit di / dt control unit 106, the comparator 202 inputs the sense voltage of the sense resistor 101, and when the input sense voltage exceeds the third predetermined threshold Vic3, the second short-circuit detection signal (for example, High signal). Is output. The threshold value Vic3 is a reference voltage that is set based on the sense ratio and sense resistance of the sense IGBT 100 with respect to a current that is several times the rated current of the IGBT 24, for example, a resistance voltage division from a highly accurate reference power source such as a band gap reference. Created with. The third threshold Vic3 may be the same size as the first threshold Vic1, or may be larger than Vic1. Note that Vic3 is preferably larger than Vic1 in order to expedite the start of the short-circuit current cutoff operation in the drive unit 105.

  The inverter 203 in the short circuit di / dt controller 106 inverts the polarity of the second short circuit detection signal (for example, High signal) output from the comparator 202 and generates a signal (for example, Low signal) that turns on the pMOS 205. The pMOS 205 is a switching element, and is turned on by a signal output from the inverter 203 in the middle of a short circuit current flowing until the current reaches a peak. At the same time as the pMOS 205 is turned on, the pMOS 211 is turned off to disconnect the on-gate resistance Rg (on) and switch to the soft-turn-on gate resistance Rg (di) 205. The soft turn-on gate resistor Rg (di) 205 is a resistor that gently charges the gate input capacitance of the IGBT 24 in order to reduce di / dt of the short-circuit current halfway until the short-circuit current of the IGBT 24 reaches a peak. For example, it has a resistance value that is several tens to several hundred times as large as the on-gate resistance Rg (on) 210.

  When receiving the first short-circuit detection signal output from the logic unit 213 of the high-speed short-circuit detection unit 102, the drive cutoff unit 104 transmits a cutoff signal to the drive unit 105 that drives the IGBT 24.

  When the drive unit 105 receives a control command signal (for example, Vnu *) sent from the host motor control unit MCU in a normal state, the drive unit 105 gives a drive signal for turning on / off the IGBT 24 to the gate electrode of the IGBT 24. The pMOS 211 is a switching element that receives the control command signal and turns on the IGBT 24. For example, the pMOS 211 can output a current of several ampere class. The on-gate resistance Rg (on) 210 is a resistor that limits a current for charging the gate input capacitance of the IGBT 24 when the IGBT 24 is turned on. The nMOS 208 is a switching element that receives the control command signal and turns off the IGBT 24. For example, the nMOS 208 can output a current of several ampere class. The off-gate resistance Rg (off) 209 is a resistor for extracting the charge accumulated in the gate input capacitance of the IGBT 24 when the IGBT 24 is turned off.

  Further, the drive unit 105 receives the cutoff signal from the drive cutoff unit 104 and the signal from the inverter 203, and after the short circuit current di / dt is reduced by the short circuit di / dt control unit 106, the IGBT 24 is changed from the normal state. Turn off slowly. That is, the drive unit 105 softly cuts off the IGBT 24 through which a short-circuit current flows. At this time, the drive unit 105 receives the cutoff signal from the drive cutoff 104, and the signal from the inverter 203 changes from Low (the pMOS 205 is on and the short-circuit di / dt control unit 106 is operating) to High (the pMOS 205 is turned on). When the switch is turned off and the short-circuit di / dt control unit changes to the operation end), the nMOS 206 is turned on for soft shut-off. The soft-blocking gate resistance Rg (sc) 207 is a resistor that slowly draws out the charge accumulated in the gate input capacitance of the IGBT 24 when the IGBT 24 is soft-turned off. For example, from the tens of the off-gate resistance Rg (off) 209 The resistance value is about several hundred times.

  According to the present embodiment, since di / dt of the short circuit current is suppressed, current / voltage oscillation at the time of rising of the short circuit current is suppressed, and the speed of the short circuit detection is improved by improving the accuracy of the short circuit detection by detecting the gate voltage and the main current. As a result, the time from when the short-circuit current flows until the interruption operation is started can be shortened. Thereby, IGBT24 can be reliably protected from the failure by a short circuit.

  In this embodiment, an IGBT is used as the power semiconductor switching element, but a MOSFET may be used. In the case of a MOSFET, a built-in diode can be used as an antiparallel diode, so that it is not necessary to connect individual diodes. In the present embodiment, one IGBT and one diode are connected, but a plurality of them may be connected in parallel according to the power capacity of the power converter. In the circuit configuration shown in FIG. 2, a MOSFET is used as a switching element in the driving device, but a bipolar junction transistor or the like may be used.

  Next, a conventional example of operation waveforms and an example of operation waveforms of this embodiment will be described with reference to FIGS. In both figures, the gate voltage waveform of the pMOS shows an inverted value. Further, the current values describing the thresholds Vic1 and Vic3 of the sense voltage are current values corresponding to Vic1 and Vic3, respectively. Note that Vic4 in the figure is a detection threshold value of the voltage between the main electrodes (collector voltage) in another embodiment (see FIGS. 5 and 6) described later.

  FIG. 3 shows an example of a conventional waveform during normal and short circuit. As a circuit configuration, in FIG. 2, the short-circuit di / dt control unit 106 is not provided, and the high-speed short-circuit detection unit 102 is replaced with a detection circuit using only a sense resistor. From the top of the figure, the waveforms are as follows: the gate voltage 75 of the pMOS 211, the gate voltage 76 of the nMOS 208, the gate voltage 77 of the nMOS 206, the gate voltage Vge 71 of the IGBT 24, the gate current Ig 72 of the IGBT 24, the collector-emitter voltage Vce 74 of the IGBT 24, and the IGBT 24. Collector current Ic73. In this conventional example, a short-circuit current starts to flow at the time of a short circuit, and when a short circuit is detected, a short circuit detection signal is input to the drive shut-off 104 via the delay circuit, and the drive shut-off 104 turns on the nMOS 206 and softly shuts off. Since the delay circuit is interposed, the short-circuit time becomes long, and the IGBT 24 may break down. Also, if the delay time is shortened, there is a possibility that the short circuit current vibrates due to erroneous detection due to noise at the time of short circuit.

  FIG. 4 shows waveform examples of the present embodiment during normal times and short circuits. From the top of the figure, the respective waveforms are the gate voltage 75 of the pMOS 211, the gate voltage 78 of the pMOS 205, the gate voltage 76 of the nMOS 208, the gate voltage 77 of the nMOS 206, the gate voltage Vge 71 of the IGBT 24, the gate current Ig 72 of the IGBT 24, the collector current of the IGBT 24. The emitter-to-emitter voltage Vce74 and the collector current Ic73 of the IGBT 24. When a short circuit current starts to flow at the time of a short circuit and the comparator 202 detects a short circuit, the pMOS 211 is turned off and the pMOS 205 is turned on. As a result, Rg (on) 210 having a small gate resistance value is switched to Rg (di) 204 having a gate resistance value larger than Rg (on) 210, and the turn-on speed of the IGBT 24 is slowed down. Further, in this embodiment, when a short circuit starts to flow at the time of a short circuit and both of the comparators 201 and 212 detect a short circuit, the short circuit detection signal is directly input to the drive cutoff 104, and the drive cutoff 104 turns on the nMOS 206 and performs a soft cutoff. To do. As a result, the short-circuit time is shortened and the IGBT 24 is unlikely to fail.

  According to the driving device of the present embodiment, the semiconductor switching element can be reliably protected from the short-circuit current. In addition, the power conversion device using the driving device of the present embodiment is less likely to fail even if an overcurrent flows due to a short circuit of the power supply or the like, so that reliability is improved.

  Next, a semiconductor device driving apparatus according to another embodiment of the present invention will be described with reference to FIGS. Note that differences from the embodiment of FIGS. 1 and 2 will be mainly described.

  FIG. 5 shows a circuit configuration including the semiconductor switching element on the lower arm side of the arm for one phase and the driving device thereof in the power module PMU in FIG.

  In the present embodiment, unlike the embodiment of FIG. 1, the voltage between the main electrodes of the IGBT 24, that is, the collector voltage, is input to the high-speed fault detector 102, and the short circuit occurs when the collector voltage and the gate voltage of the IGBT 24 exceed a predetermined threshold value. A detection signal is output. Further, the short-circuit di / dt control unit 106 inputs the collector voltage and gate voltage of the IGBT 24, and when the collector voltage exceeds a predetermined threshold value in a short-circuit state, the IGBT 24 is gently turned on to reduce the short-circuit current di / dt. To reduce. The drive shut-off unit 104 receives the short-circuit detection signal from the high-speed short-circuit detection unit 102 and the gate voltage of the IGBT 24, and reliably outputs a cut-off signal to the drive unit 105 in a short-circuit state. The drive unit 105 softly cuts off the IGBT 24 after di / dt reduction based on the cut-off signal and the operating state of the short-circuit di / dt control unit. Other circuit configurations and operations are the same as those of the embodiment of FIG.

  FIG. 6 shows a specific example of the circuit configuration of the embodiment of FIG.

  The diode 401 is for detecting the collector voltage of the IGBT 24. The diode 401 is turned on when the IGBT 24 is turned on and the collector voltage falls below the power supply Vcc, and the collector voltage of the IGBT 24 is controlled by the high-speed short-circuit detecting unit 102 and the short-circuit di / dt control. Output to the unit 301. The resistor 402 is connected to the power supply Vcc and the cathode electrode of the diode 401, and limits the current value when the diode 401 becomes conductive. The comparator 201 receives an addition value of the collector voltage when the IGBT 24 is turned on and the forward voltage of the diode 401, and outputs a first detection signal (for example, a High signal) when a fourth predetermined threshold Vic4 is exceeded. . The threshold value Vic4 is a reference voltage set based on the collector-emitter voltage of the IGBT 24 when a current several times the rated current of the IGBT 24 flows, for example, a resistance voltage division from a highly accurate reference power source such as a band gap reference. Created with. Note that the gate voltage threshold Vic2 is set to a high level gate voltage Vg1 of the IGBT 24, that is, a voltage larger than the gate-emitter voltage in a normal state, as in the specific example of FIG.

  The short-circuit di / dt control unit 106 turns on the IGBT 24 more slowly than usual when the sum of the collector voltage at the turn-on of the IGBT 24 and the forward voltage of the diode 401 exceeds a predetermined threshold, and the short-circuit current di Reduce / dt. The comparator 202 inputs an added value of the collector voltage at the turn-on of the IGBT 24 and the forward voltage of the diode 401, and outputs a second short-circuit detection signal (for example, a High signal) when the added value exceeds a predetermined threshold value Vic4. To do. Since the collector voltage of the IGBT 24 becomes higher than the normal ON voltage from the time when the short-circuit current rises during the period in which the short-circuit current flows, the threshold value in the short-circuit di / dt control unit 106 is determined. Both Vic4 and the fourth threshold value Vic4 in the above-described high-speed short-circuit detection unit 102 may be set to a value larger than the ON voltage and may be the same size. Thereby, the circuit for setting the threshold value can be simplified.

  The logic unit 403 in the short-circuit di / dt control unit 106 inputs the second short-circuit detection signal (for example, High signal) output from the comparator 202 and the gate voltage of the IGBT 24, and determines whether or not it is a short circuit. That is, the logic unit 403 determines that a short circuit occurs when the collector voltage of the IGBT 24 exceeds the threshold value Vic4 of the comparator 202 and the gate voltage of the IGBT 24 is turned on. Here, by inputting the gate voltage of the IGBT 24 to the logic unit 403, erroneous detection of a short circuit can be prevented. As for the detection of the gate voltage, it is only necessary to detect that the gate voltage is on, and it is not necessary to set a highly accurate threshold value. The pMOS 205 is a switching element. When the logic unit 403 determines that the short circuit has occurred, the pMOS 205 is turned on in the middle of the short circuit current reaching the peak. At the same time as the pMOS 205 is turned on, the pMOS 211 is turned off to disconnect the on-gate resistance Rg (on) and switch to the soft-turn-on gate resistance Rg (di) 205.

  The drive cut-off unit 104 receives the first short circuit detection signal output from the logic unit 213 and the gate voltage of the IGBT 24, and sends a cut-off signal to the drive unit 105 that drives the IGBT 24. Here, malfunction can be prevented by using the gate voltage as well. As for the detection of the gate voltage, it is only necessary to detect that the gate voltage is on, and it is not necessary to set a highly accurate threshold value.

  The drive unit 105 receives the cut-off signal from the drive cut-off unit 104 and the signal from the logic unit 403, and after the di / dt of the short-circuit current is reduced by the short-circuit di / dt control unit 106, the drive unit 105 soft-cuts the IGBT 24. At this time, the drive unit 105 receives the cutoff signal from the drive cutoff 104, and the pMOS 205 is off from the operating state of the short-circuit di / dt control unit 106 in which the pMOS 205 is on based on the signal from the logic unit 203. When the shorted di / dt controller changes to the non-operating state, the nMOS 206 is turned on for soft shut-off.

  The other circuit configurations and operations in the specific example shown in this figure are the same as those in the specific example of FIG. Further, the operation waveform of this embodiment is the same as the waveform shown in FIG. Further, also in this embodiment, a MOSFET may be used as the power semiconductor switching element. Further, a plurality of IGBTs and diodes may be connected in parallel.

  Also with the driving apparatus of the present embodiment, the semiconductor switching element can be reliably protected from the short-circuit current. In addition, the power conversion device using the driving device of the present embodiment is less likely to fail even if an overcurrent flows due to a short circuit of the power supply or the like, so that reliability is improved.

  In addition, this invention is not limited to each Example mentioned above, Various modifications are included. For example, each of the above-described embodiments has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and further, the configuration of another actual example can be added to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace other configurations for a part of the configuration of each embodiment.

  For example, the power semiconductor switching element controlled by the driving device may be a power MOSFET in addition to the IGBT. The main current may be detected using a shunt resistor or a current transformer in addition to the current sensing IGBT.

24 ... IGBT, 25 ... Diode element, 100 ... IGBT for current sensing,
101 ... sense resistor, 102 ... high-speed short-circuit detection unit, 104 ... drive cutoff unit,
105 ... Drive unit, 106 ... Short circuit di / dt control unit, 201 ... Comparator, 202 ... Comparator,
203 ... Inverter, 204 ... Resistor, 205 ... pMOS, 206 ... nMOS,
207 ... resistor, 208 ... nMOS, 209 ... resistor, 210 ... resistor,
211 ... pMOS, 212 ... comparator, 213 ... logic unit, 401 ... diode,
402: Resistor, 403: Logic part,
INV ... Inverter device, PMU ... Power module, DCU ... Drive circuit device,
MCU ... Electric motor control device, M ... Motor, Cu, Cv, Cw ... Current sensor,
Au ... U phase arm, Av ... V phase arm, Aw ... W phase arm, SEC ... Electrolytic capacitor,
BAT ... High voltage battery

Claims (9)

A drive unit for creating a drive signal for controlling on / off of the semiconductor switching element, and supplying the drive signal to a control electrode of the semiconductor switching element;
A protection circuit for protecting the semiconductor switching element from a short-circuit current;
In a drive device for a semiconductor element comprising:
The protection circuit is
A short circuit is detected based on a main current flowing through the semiconductor switching element and a control voltage of the semiconductor switching element, and a short circuit detection unit that outputs a short circuit detection signal when a short circuit is detected;
A short-circuit di / dt controller that reduces the di / dt of the short-circuit current if a short circuit is detected based on the main current;
A drive cutoff unit that transmits a cutoff command signal to the drive unit based on the short circuit detection signal;
With
The driving device for a semiconductor device, wherein when the short circuit di / dt control unit reduces the di / dt of the short circuit current, the drive unit turns off the semiconductor switching device based on the cutoff command signal. In the drive device of the semiconductor element according to claim 1,
A semiconductor element characterized in that a current detection threshold value of the short circuit di / dt control unit is larger than a current detection threshold value of the short circuit detection unit, and a control voltage detection threshold value of the short circuit detection unit is larger than a control voltage in a normal state. Drive device. In the drive device of the semiconductor element according to claim 1 or 2,
The drive unit for a semiconductor element, wherein the drive unit softly shuts off the semiconductor switching element when the semiconductor switching element is turned off based on the shutoff command signal. A drive unit for creating a drive signal for controlling on / off of the semiconductor switching element, and supplying the drive signal to a control electrode of the semiconductor switching element;
A protection circuit for protecting the semiconductor switching element from a short-circuit current;
In a drive device for a semiconductor element comprising:
The protection circuit is
A short circuit is detected based on the voltage between the main electrodes of the semiconductor switching element and the control voltage of the semiconductor switching element, and a short circuit detection unit that outputs a short circuit detection signal when a short circuit is detected,
A short-circuit di / dt controller that reduces the di / dt of the short-circuit current if a short circuit is detected based on the voltage between the main electrodes;
A drive cutoff unit that transmits a cutoff command signal to the drive unit based on the short circuit detection signal;
With
The driving device for a semiconductor device, wherein when the short circuit di / dt control unit reduces the di / dt of the short circuit current, the drive unit turns off the semiconductor switching device based on the cutoff command signal. In the drive device of the semiconductor element according to claim 4,
The voltage detection threshold value of the short-circuit di / dt control unit and the voltage detection threshold value of the short-circuit detection unit are the same, and the control voltage detection threshold value of the short-circuit detection unit is larger than the control voltage in a normal state. A semiconductor element driving apparatus. In the drive device of the semiconductor element according to claim 4 or 5,
The short circuit di / dt control unit detects a short circuit based on the voltage between the main electrodes and the control voltage. The drive device for a semiconductor element according to any one of claims 4 to 6,
The drive shut-off unit transmits a shut-off command signal to the drive unit based on the short-circuit detection signal and the control voltage. The drive device for a semiconductor element according to any one of claims 4 to 7,
The drive unit for a semiconductor element, wherein the drive unit softly shuts off the semiconductor switching element when the semiconductor switching element is turned off based on the shutoff command signal. The upper arm side includes a plurality of arm circuits in which both ends of a series circuit of a semiconductor switching element on the upper arm side and a semiconductor switching element on the lower arm side are connected to a DC power source, and a series connection point is connected to an AC terminal; In a power conversion device comprising a plurality of drive circuit devices for controlling on / off of the semiconductor switching element and the lower arm side semiconductor switching element,
9. The power conversion device according to claim 1, wherein the drive circuit device is a drive device for a semiconductor element according to any one of claims 1 to 8.

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