JP5298557B2 - Voltage-driven semiconductor device gate drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of large loss at a normal current and large loss of an apparatus and hence upsizing of the apparatus in a system which increases an on-gate resistance value of an opposing arm to suppress a surge voltage and voltage fluctuations when FWD is in a small and reverse-recovery current state. <P>SOLUTION: A gate drive includes a voltage detection circuit 12 for detecting a voltage generated at an internal inductance 5 connected to IGBT3 during a turn-off and a comparison circuit 13 for comparing a detection time from an input of an off-gate signal to voltage detection by a voltage detection circuit 12 with a predetermined setting time. A gate driving resistor 8 or 11 for turn-on is switched with switch devices 6, 10 according to a comparative result. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a gate drive device for a voltage-driven semiconductor element applied to a power conversion device, and more particularly to a gate drive technique for suppressing a surge voltage and an oscillating voltage generated when a freewheeling diode reversely recovers.

  FIG. 7 shows a circuit configuration diagram of a known voltage source inverter that uses an IGBT as a voltage-driven semiconductor element. 21 is a three-phase AC power source, 22 is a rectifier circuit, 23 is a smoothing capacitor, 24 to 29 are IGBTs with diodes connected in antiparallel, and 30 is a motor load.

  FIG. 8 is an equivalent circuit diagram for one phase of the voltage source inverter shown in FIG. In FIG. 8, 36 is a smoothing capacitor, 37 is a wiring inductance of the circuit, 38 is an L load, 3 and 33 are IGBTs, 4 and 34 are free wheel diodes (hereinafter referred to as FWD), and 5 and 35 are internal inductances of the IGBT module. 32 is an upper arm IGBT module, 2 is a lower arm IGBT module, 31 is a gate drive device (GDU1) connected to the upper arm IGBT module 32, and 1 is a gate drive device (1) connected to the lower arm IGBT module 2 GDU2).

  FIG. 9 shows a circuit diagram of the main part of the gate driving device 1. In FIG. 9, 6 and 7 are switch elements for turning on and off the IGBT, 8 is a gate-on resistance, 9 is a gate-off resistance, and 15 is an interface circuit that outputs an on signal and an off signal. This type of gate driving device is as disclosed in Patent Document 1.

  10 and 11 show the operation waveforms of the collector-emitter voltage VCE and the collector current Ic of the IGBT 3 when the IGBT 3 of FIG. 9 is switched, the anode-cathode voltages VAK and FWD of the FWD 34 (the reverse of the forward current IF). The operation waveform of the recovery current is shown. Here, FIG. 10 shows an operation waveform at a normal current, and FIG. 11 shows an operation waveform at a small current (generally about 1/10 or less of the element rated current).

  In FIG. 8, when the IGBT 3 is in the ON state, a current flows through the path of the smoothing capacitor 36 → the wiring inductance 37 → the L load 38 → the IGBT 3 → the internal inductance 5 → the smoothing capacitor 36 (on mode). When the IGBT 3 is turned off, the collector-emitter voltage VCE of the IGBT 3 increases. When the VCE reaches the DC voltage Ed, the FWD 34 is turned on, whereby the load current IL is commutated to the FWD 34, and a current flows through the path of L load 38 → FWD 34 → L load 38 (free wheeling mode). When the IGBT 3 is turned on from this state, a reverse recovery current flows through the FWD 34 through the path of the smoothing capacitor 36 → the circuit wiring inductance 37 → FWD 34 → IGBT 3 → the smoothing capacitor 36, and reverse recovery is performed. When the reverse recovery operation of the FWD 34 is completed, the IGBT 3 is turned on again (on mode). Here, a surge voltage Vp1 is generated during reverse recovery of the FWD 34 (see FIG. 10).

  In the freewheeling mode of FIG. 8, when the FWD 34 reversely recovers when the current is small, a high surge voltage Vp2 and a high-frequency vibration phenomenon occur as shown in FIG. 11, and in the worst case, the generated noise increases. At the same time, there is a possibility of element destruction.

In order to prevent the element breakdown due to the surge voltage and the vibration phenomenon during the low current reverse recovery of the FWD, the surge voltage and the vibration phenomenon are suppressed by increasing the gate-on resistance 8 of the IGBT 3 in the conventional gate drive device of FIG. be able to. A method of relaxing the rise of the collector current of the IGBT by increasing the gate resistance value is disclosed in Patent Document 2.
JP 2002-165435 A Japanese Patent Laid-Open No. 10-32976

  As described above, if the gate-on resistance 8 is increased in order to suppress the surge voltage and the vibration phenomenon at the time of reverse recovery of the FWD at a small current, there is a problem that the turn-on loss at the normal current increases.

In order to solve the above-mentioned problem, in the first invention, in a gate driving device for driving a voltage-driven semiconductor element used in a power converter, it is generated in an internal inductance connected to the voltage-driven semiconductor element at turn-off. An inductance voltage detecting means for detecting a voltage to be detected, a comparing means for comparing a detection time from when an off-gate signal is input until the inductance voltage detecting means detects a voltage with a predetermined set time, and Switching means for switching the gate drive condition for turn-on in response, and when the detection time from when the off-gate signal is input until the inductance voltage detection means detects the voltage is longer than the predetermined set time The switching means normally uses a gate-on resistance as the next turn-on gate drive condition. It switched to the gate-on resistance of the high resistance than the gate-on resistance.

In the second invention, in the gate driving device for driving the voltage driven semiconductor element used in the power converter , the inductance voltage detecting means for detecting the voltage generated in the internal inductance connected to the voltage driven semiconductor element at the turn-off time Comparing means for comparing a detection time from when the off-gate signal is input until the inductance voltage detection means detects a voltage with a predetermined set time, and a gate drive condition for turn-on according to the comparison result. Switching means for switching, and when the detection time from when the off-gate signal is input to when the inductance voltage detection means detects a voltage is longer than the predetermined set time, the switching means is a gate drive power supply voltage. From the normal gate drive power supply voltage as the gate drive condition for the next turn-on It has switched to the gate drive power supply voltage of the voltage.

  According to the present invention, when this gate driving device is applied to a power conversion device such as an inverter, it is possible to detect FWD without increasing the turn-on loss only by detecting the time when the collector current starts flowing when the self-arm element is turned off. Surge voltage and vibration phenomenon during small current reverse recovery can be suppressed, noise generated can be reduced, and element breakdown can be prevented. The same effect can be obtained when applied to a power converter in which a plurality of IGBTs are connected in series to each arm.

  The main points of the present invention are an inductance voltage detecting means for detecting a voltage generated in an internal inductance connected to the voltage-driven semiconductor element at the time of turn-off, and from when an off-gate signal is inputted until the inductance voltage detecting means detects the voltage. Comparing means for comparing the detected time with a predetermined set time, and switching the gate drive condition for turn-on according to the comparison result.

  FIG. 1 shows a first embodiment of the present invention. In the embodiment of FIG. 1, 1 is a gate driving device, 2 is an IGBT module, 3 is an IGBT, 4 is an FWD, and 5 is an inductance inside the IGBT module. As shown in FIG. 1, the IGBT module 2 includes IGBTs 3, FWD 4, and internal inductance 5, and the gate driving device 1 is connected to the gate terminal G, main emitter terminal E 1, and auxiliary emitter terminal E 2 of the IGBT module 2.

  FIG. 2 shows a circuit configuration example of the gate driving device of the present invention. Components having the same functions as those of the conventional example of FIG. In FIG. 2, a voltage detection circuit 12 for detecting a voltage generated in the internal inductance 5 of the IGBT module 2 at the time of turn-off, and a voltage detection circuit 12 after the turn-off signal is input to the conventional gate drive circuit (FIG. 9). A detection time comparison circuit 13 that compares a time until detection with a predetermined set time, a resistance value selection circuit that selects a gate-on resistance value according to the result of the detection time comparison circuit 13, and a high resistance during small current reverse recovery 11 includes a switch element 11 that drives the IGBT 3.

  Next, the operation of the gate driving apparatus according to the present invention will be described with reference to FIGS. FIG. 3 shows an operation waveform at a normal current, and FIG. 4 shows an operation waveform at a small current. In FIG. 2, when the off signal is output from the interface circuit 15 and the gate voltage VGE falls to the threshold voltage VGE (th), the collector-emitter voltage VCE starts to rise. When VCE reaches the power supply voltage Ed, the collector current Ic decreases and a voltage Vlin is generated in the internal inductance 5 of the IGBT module 2. When the voltage detection circuit 12 detects this voltage VLin, the detection time comparison circuit 13 compares the time T1 from when the turn-off signal is output until the voltage detection circuit 12 detects the voltage with a predetermined set time T0. To do.

  When the current at turn-off is small, the time for charging the feedback capacity (collector-gate capacity) of the IGBT becomes long, and when the current at turn-off is large, the charge time becomes short. As a result, the time T1 until the collector current Ic starts to decrease is long when the current is small and short when the current is large. Therefore, if the comparison result of the detection time comparison circuit 13 is T1 <T0 (see FIG. 3), the resistance value selection circuit 14 estimates that the FWD of the opposing arm at the next turn-on reversely recovers with the normal current. The normal gate-on resistance 8 is selected. If the comparison result is T1> T0 (see FIG. 4), the resistance value selection circuit 14 estimates that the FWD of the opposing arm at the next turn-on reversely recovers with a small current, and sets the high resistance gate-on resistance 11 Select.

  Next, when an on signal is output from the interface circuit 15, if the normal gate-on resistance 8 is selected, the switch element 6 is turned on, and the IGBT 3 is turned on by the normal gate-on resistance 8. When the high resistance gate-on resistance 11 is selected, the switch element 10 is turned on, and the IGBT 3 is turned on by the high resistance gate-on resistance 11.

  As a result, when the FWD of the opposing arm reverses with normal current, it can be turned on with normal resistance, and when it recovers with small current, it can be turned on with high resistance, increasing the turn-on loss during normal current operation. In addition, it is possible to suppress the surge voltage and vibration phenomenon when the FWD is reversely recovered with a small current.

FIG. 5 shows a second embodiment of the present invention.
The difference from FIG. 2 which is the first embodiment is that when the FWD of the opposite arm reversely recovers with a normal current, the IGBT is turned on with a normal resistance, and when the reverse recovery with a small current is high, the first embodiment is high. On the other hand, in the second embodiment, the gate resistance value is not switched and the IGBT is turned on with the normal gate drive power supply voltage P when the FWD of the opposite arm is reversely recovered with the normal current. When reverse recovery is performed with current, it is turned on at a lower gate drive power supply voltage P1 than usual. In order to realize this, a power supply voltage selection circuit 14a is provided in place of the resistance value selection circuit 14, and the series circuit of the switch element 10 and the diode 11a is used rather than the normal gate drive power supply voltage P without using the resistor 11 of FIG. The circuit configuration is such that it is connected to the connection point of the low gate drive power supply voltage P 1, the switch element 6 and the resistor 8.

As a result, the FWD of the opposite arm can be turned on with a normal gate drive power supply voltage when reversely recovered with a normal current, and can be turned on with a lower gate drive power supply voltage than normal when reversely recovered with a small current. Without increasing the turn-on loss during the current operation, it is possible to suppress the surge voltage and vibration phenomenon when the FWD reversely recovers with a small current.

  FIG. 6 shows a third embodiment of the present invention. FIG. 6 shows an example in which a plurality of IGBT modules connected to the gate driving device according to the present invention are connected in series (two series components are shown). In FIG. 6, the IGBT module 2 is composed of IGBT3, FWD4, and internal inductance 5, and the IGBT module 17 is composed of IGBT18, FWD19, and internal inductance 20, and includes the gate terminal G, main emitter terminal E1, auxiliary circuit of the IGBT module2. The gate driver 1 is connected to the emitter terminal E2, and the gate driver 2 is connected to the gate terminal G, the main emitter terminal E1, and the auxiliary emitter terminal E2 of the IGBT module 17.

In this embodiment, the gate drivers 1 and 2 drive the IGBTs 2 and 17 connected in series with the synchronized signal as an input. The operation of each gate driving device is the same as in the first and second embodiments described above.

  From the above, even when multiple IGBT modules are connected in series, the surge voltage and vibration phenomenon when FWD reversely recovers with a small current without increasing the turn-on loss during normal current operation for each IGBT module. It becomes possible to suppress.

  The present invention can be applied to power conversion devices such as switching power supplies, electric motor drive devices, and uninterruptible power supply devices that are configured using a switch circuit in which an FWD is connected in antiparallel with the IGBT.

Connection diagram of gate drive device and IGBT module showing configuration of the present invention Circuit configuration of gate drive apparatus showing first embodiment of the present invention Operation explanatory diagram of FIG. 2 at normal current Operation explanatory diagram of FIG. 2 at a small current Circuit configuration of gate driving apparatus showing second embodiment of the present invention Connection diagram of gate drive device and IGBT module showing third embodiment of the present invention Circuit configuration diagram of known voltage source inverter using IGBT Equivalent circuit diagram for one phase in Fig. 7 Circuit configuration example of a conventional gate drive device 9 is an operation explanatory diagram of normal current. Explanation of operation in Fig. 9 at low current

Explanation of symbols

1, 16, 31 ... Gate drive unit (GDU)
2, 17, 32 ... IGBT module 3, 18, 33 ... IGBT
4, 19, 34 ... FWD
5, 20, 24 to 29, 35 ... internal inductance 6, 7, 10 ... switch element 8, 9, 11 ... resistor 11a ... diode 12 ... voltage detection circuit 13 ... detection Time comparison circuit 14 ... resistance value selection circuit 14a ... drive power supply selection circuit 15 ... interface circuit 21 ... AC power supply 22 ... rectifier 23, 36 ... capacitor 30 ... electric motor 37 ..Wiring inductance 38 ... L load

Claims (2)

In a gate driving device for driving a voltage driven semiconductor element used in a power converter, an inductance voltage detecting means for detecting a voltage generated in an internal inductance connected to the voltage driven semiconductor element at the time of turn-off, and an off gate signal are input. Comparison means for comparing a detection time from when the inductance voltage detection means detects a voltage to a preset set time, and a switching means for switching the gate drive condition for turn-on according to the comparison result. When the detection time from when the off-gate signal is input until the inductance voltage detection means detects the voltage is longer than the predetermined set time, the switching means sets the gate-on resistance as the next turn-on gate drive condition. Switch to higher gate-on resistance than normal gate-on resistance The gate drive voltage driven type semiconductor element, characterized in that. In a gate driving device for driving a voltage driven semiconductor element used in a power converter, an inductance voltage detecting means for detecting a voltage generated in an internal inductance connected to the voltage driven semiconductor element at the time of turn-off, and an off gate signal are input. Comparison means for comparing a detection time from when the inductance voltage detection means detects a voltage to a preset set time, and a switching means for switching the gate drive condition for turn-on according to the comparison result. When the detection time from when the off-gate signal is input to when the inductance voltage detection means detects a voltage is longer than the predetermined set time, the switching means supplies the gate drive power supply voltage to the next turn-on gate drive. As a condition, the gate drive voltage is lower than the normal gate drive voltage The gate drive voltage driven type semiconductor element and switches the voltage.

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