Power semiconductor module and motor drive system using same

Abstract

To provide a power semiconductor module in which a gate resistor is controlled without using a dedicated control line so that gate voltage oscillation can be prevented while an increase of switching loss is suppressed, and provide a motor driving system using the power semiconductor module.SOLUTION: A power semiconductor module (8) includes a switching element (SW1), and a gate resistor (11) that is connected to a gate (G1) of the switching element. The gate resistor is a variable resistor (Rgvari1) the resistor value of which becomes greater when a gate voltage (VgeH), which is outputted from a gate driving circuit (36) driving the switching element for a period from turning-on of the switching to turning-off of the switching element, is higher than a threshold value of the switching element but is lower than a prescribed value (Vgep1) of the gate voltage, compared to a case where the gate voltage is equal to the prescribed value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power semiconductor module and a motor drive system using the same. [Background technology]

[0002] A power conversion device has functions such as AC-DC conversion, DC-AC conversion, or frequency conversion of AC power, voltage conversion of DC power, etc. To perform such conversion functions, the power conversion device has a power conversion circuit that converts power by the on / off operation of a power semiconductor module with a switching function.

[0003] A power semiconductor module is turned on by controlling the gate voltage between the gate terminal and emitter terminal (or source terminal) to High (positive voltage) by the gate drive circuit, and turned off by controlling it to Low (0V or negative voltage).The gate drive circuit is further controlled by a higher-level controller.

[0004] Power semiconductor modules include 1-in-1 modules equipped with single or multiple parallel-connected semiconductor switching elements (hereafter referred to as "switching elements"), and 2-in-1 modules in which two switching elements are connected in series inside the module to form a half-bridge circuit in one module. There are also power semiconductor modules called IPMs (Intelligent Power Modules) that incorporate gate drive circuits and self-protection circuits (such as short circuit and overheating protection).

[0005] In a power conversion device equipped with a power semiconductor module, if the load is shorted or if one of two series-connected switching elements is shorted due to malfunction or failure, the power supply is shorted with low impedance and a large short-circuit current flows through the circuit. For this reason, if a short circuit occurs, it is detected by a short circuit detection circuit and the short-circuit current is cut off by other healthy switching elements, thereby protecting the device from short circuits.

[0006] However, in the event of a short circuit, oscillation of the gate voltage caused by parasitic inductance and parasitic capacitance of wiring, switching elements, and other electrical components in the power conversion circuit may be amplified by the amplification function of the switching elements.

[0007] In response to this, the technique described in Patent Document 1 is known as a conventional technique for preventing gate voltage oscillation during a short circuit.

[0008] In this conventional technology, in a power semiconductor module with a built-in gate drive circuit, gate voltage oscillation during a short circuit is prevented by increasing the gate resistance using a variable resistor during a short circuit. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2018-117457 A Summary of the Invention [Problem to be solved by the invention]

[0010] In the conventional technology, a dedicated control wiring is required to control the resistance value of the variable resistor. This may complicate the wiring configuration in the power semiconductor module, which may lead to an increase in the size of the power semiconductor module. In addition, the provision of the dedicated control wiring may cause new parasitic inductance and parasitic capacitance. Furthermore, in the conventional technology, the effect of controlling the variable resistor on switching loss is not fully considered.

[0011] Therefore, the present invention provides a power semiconductor module that can control the gate resistance without using a dedicated control line, thereby preventing gate voltage oscillation while suppressing an increase in switching loss, and a motor drive system that uses this power semiconductor module. [Means for solving the problem]

[0012] In order to solve the above problems, a power semiconductor module according to the present invention includes a switching element and a gate resistor connected to a gate of the switching element, the gate resistor being ,vinegar The gate voltage output from the gate drive circuit that drives the switching element is higher than the threshold voltage of the switching element and lower than a predetermined value of the gate voltage. Lower than a given threshold When the gate voltage is at a certain value, the resistance value becomes larger than when the gate voltage is at a certain value. When a short circuit current flows through the switching element, the gate voltage starts to decrease toward a voltage lower than the predetermined threshold voltage, and then increases from a voltage higher than the threshold voltage of the switching element to a voltage lower than the predetermined threshold voltage. do.

[0013] In order to solve the above problems, a motor drive device according to the present invention includes a power conversion device that drives a motor, and a main circuit of the power conversion device is formed by a power semiconductor module, and this power semiconductor module is the power semiconductor module according to the present invention. Effect of the Invention

[0014] According to the present invention, it is possible to prevent gate voltage oscillation while suppressing an increase in switching loss by controlling the resistance value of the gate resistor without using a dedicated control wiring for the variable resistor.

[0015] Problems, configurations and effects other than those described above will become apparent from the following description of the embodiments. [Brief description of the drawings]

[0016] [Figure 1] 1 is a circuit diagram showing a configuration of a power semiconductor module and a gate drive circuit according to a first embodiment of the present invention. [Diagram 2] 2 is a circuit diagram illustrating a configuration of a variable resistor in the first embodiment. FIG. [Diagram 3] 4 is a time chart showing the operation of the power semiconductor module of the first embodiment. [Figure 4] FIG. 11 is a circuit diagram showing a configuration of a power semiconductor module according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a schematic diagram showing the appearance of a power semiconductor module according to a third embodiment of the present invention. [Figure 6] FIG. 11 is a schematic diagram showing an internal configuration of a power semiconductor module according to a third embodiment of the present invention. [Figure 7] FIG. 11 is a circuit diagram showing a configuration of a motor drive system according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the embodiments of the present invention will be described with reference to the drawings by way of the following Examples 1 to 3. In each drawing, the same reference numerals indicate the same components or components having similar functions. EXAMPLES

[0018] A first embodiment of the present invention will be described with reference to Figures 1 to 3. First, the configuration of the first embodiment will be described with reference to Figure 1, and then the operation of the first embodiment will be described with reference to Figures 2 and 3.

[0019] FIG. 1 is a circuit diagram showing a configuration of a power semiconductor module according to a first embodiment of the present invention and a gate drive circuit for controlling the power semiconductor module.

[0020] 1, in the first embodiment, the power semiconductor module 8 is a so-called 2-in-1 module. In the power semiconductor module 8, an upper arm made of a parallel connection of a switching element SW1 and a diode 10 and a lower arm made of a parallel connection of a switching element SW2 and a diode 12 are connected in series to each other to form a half-bridge circuit. Note that the first embodiment can also be applied to a case where separate 1-in-1 modules are used as the upper arm and the lower arm.

[0021] As the switching elements SW1 and SW2, insulated gate switching elements such as IGBTs (Insulated Gate Bipolar Transistors) as shown in the figure, or MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) can be used. As the diodes 10 and 12, in addition to SBDs (Schottky Barrier Diodes), pn junction diodes, etc. can be used. The semiconductor material constituting the switching elements SW1 and SW2 and the diodes 10 and 12 may be Si or a wide gap semiconductor such as SiC. When MOSFETs are used as the switching elements SW1 and SW2, the parasitic diodes (body diodes) of the MOSFETs may be used as the diodes 10 and 12.

[0022] The switching element SW1 has a collector terminal C1, a gate terminal G1, and an emitter terminal E1. The switching element SW2 has a collector terminal C2, a gate terminal G2, and an emitter terminal E2. The collector terminal C1, the output terminal AC which is the connection point between the emitter terminal E1 and the collector terminal C2, and the emitter terminal E2 are respectively a high potential terminal, an intermediate potential terminal, and a low potential terminal in the series connection of the upper arm and the lower arm.

[0023] Furthermore, the switching element SW1 has a collector auxiliary terminal C1AUX for detecting the collector voltage, and a gate auxiliary terminal G1AUX and an emitter auxiliary terminal E1AUX for inputting the gate drive voltage. The switching element SW2 has a collector auxiliary terminal C2AUX for detecting the collector voltage, and a gate auxiliary terminal G2AUX and an emitter auxiliary terminal E2AUX for inputting the gate drive voltage.

[0024] These terminals (C1, AC, E2, C1AUX, G1AUX, E1AUX, C2AUX, G2AUX, E2AUX) are electrically connected to an external circuit (main circuit, gate drive circuit). These terminals are connected to corresponding electrode terminals in the power semiconductor module 8. Therefore, these electrode terminals are connected to the external circuit.

[0025] The upper arm is connected between the gate terminal G1 of the switching element SW1 and the gate auxiliary terminal G1AUX, and includes a variable resistor Rg vari1 The lower arm is connected between the gate terminal G2 of the switching element SW2 and the gate auxiliary terminal G2AUX, and includes a variable resistor Rg vari2 Equipped with.

[0026] FIG. 1 shows a half-bridge circuit configuration with an upper arm drive in which an inductive load 7 is connected between the output terminal AC and the emitter terminal E2. The collector terminal C1 and the emitter terminal E2 are connected to a smoothing capacitor 6 via wires 4 and 5, and the smoothing capacitor 6 is connected to a DC power supply 1 via wires 2 and 3. The smoothing capacitor 6 is charged to a DC power supply voltage Vcc by the DC power supply 1. Such a main circuit configuration corresponds to, for example, one phase of a three-phase inverter that drives a three-phase AC motor. In this case, the inductive load 7 corresponds to one phase of the three-phase winding of the three-phase AC motor.

[0027] The gate auxiliary terminals G1AUX, G2AUX and the emitter auxiliary terminals E1AUX, E2AUX are connected to the gate drive circuit 36. The gate drive circuit 36 ​​charges the gate voltage VgeH of the upper arm to the positive power supply voltage Vgep1 of the gate drive circuit 36, thereby turning on the upper arm, and charges the upper arm to the negative power supply voltage Vgen1 of the gate drive circuit 36, thereby turning off the upper arm. Also, the gate drive circuit 36 ​​charges the gate voltage VgeL of the lower arm to the positive power supply voltage Vgep2 of the gate drive circuit 36, thereby turning on the lower arm, and charges the lower arm to the negative power supply voltage Vgen2, thereby turning off the lower arm.

[0028] The gate drive circuit 36 ​​includes DC power supplies 17 and 28 which are positive voltage power supplies for control, and DC power supplies 18 and 29 which are negative voltage power supplies for control, and charges smoothing capacitors 19 and 30 for the positive voltage power supplies to positive power supply voltages Vgep1 and Vgep2, respectively, and charges smoothing capacitors 20 and 31 for the negative voltage power supplies to negative power supply voltages Vgen1 and Vgen2, respectively.

[0029] In the gate drive circuit 36, the switching element 21 is turned on when the upper arm is turned on, and charges the gate voltage VgeH of the upper arm to the positive power supply voltage Vgep1 via the gate resistor Rgon1. The switching element 32 is turned on when the lower arm is turned on, and charges the gate voltage VgeL of the lower arm to the positive power supply voltage Vgep2 via the gate resistor Rgon2.

[0030] In the gate drive circuit 36, the switching element 24 is turned on when the upper arm is off, and charges the gate voltage VgeH of the upper arm to the negative power supply voltage -Vgen1 via the gate resistor Rgoff1. The switching element 35 is turned on when the lower arm is off, and charges the gate voltage VgeL of the lower arm to the negative power supply voltage -Vgen2 via the gate resistor Rgoff2.

[0031] In the first embodiment, as shown in FIG. 1, junction bipolar transistors are used as the switching elements 21, 24, 32, and 35, but the present invention is not limited to this and MOSFETs or the like may also be used.

[0032] In the gate drive circuit 36, the series circuit of the Zener diode 16 and the switching element Q1, and the series circuit of the Zener diode 27 and the switching element Q2 are gate voltage step-down circuits when a short circuit is detected. In the upper arm, the potential of C1AUX is compared with the short circuit detection reference potential 14 by the comparator 15, and if the potential of C1AUX is higher than the short circuit detection reference potential 14, a short circuit is detected and the switching element Q1 is switched from off to on. As a result, the gate voltage VgeH of the upper arm is stepped down from Vgep1 to the breakdown voltage of the Zener diode 16. In the lower arm, the potential of C2AUX is compared with the short circuit detection reference potential 25 by the comparator 26, and if the potential of C2AUX is higher than the short circuit detection reference potential 25, a short circuit is detected and the switching element Q2 is switched from off to on. As a result, the gate voltage VgeL of the lower arm is stepped down from Vgep2 to the breakdown voltage of the Zener diode 27.

[0033] The switching elements 21, 24, 32, and 35 in the gate drive circuit 36 ​​are on / off controlled based on PWM (Pulse Width Modulation) signals S1 and S2 input from a controller (not shown) of the power conversion device.

[0034] 2 is a circuit diagram showing the configurations of the variable resistors 11 and 13 in the first embodiment (FIG. 1). Since the variable resistors 11 and 13 have the same configuration, FIG. 2 shows the circuit configuration of only the variable resistor 11 out of the variable resistors 11 and 13.

[0035] As shown in Fig. 2, the variable resistor 11 is configured by connecting a resistor RgSC1 and a P-channel MOSFET Qp1 in parallel. In the first embodiment, the resistor RgSC1 is a fixed resistor having a predetermined resistance value. The gate terminal Gp1 of Qp1 is connected to the emitter terminal E1 of the switching element SW1. The source terminal Sp1 of Qp1 is connected to the gate auxiliary terminal G1AUX. The drain terminal Dp1 of Qp1 is connected to the gate terminal G1 of the switching element SW1.

[0036] The resistor RgSC1 may be a semi-fixed resistor.

[0037] When the switching element SW1 is in the ON state, the voltage between the gate terminal Gp1 and the source terminal Sp1 is higher in the negative direction than the threshold voltage VthQp1 (negative value) of the P-channel MOSFET Qp1, so that the P-channel MOSFET Qp1 is in the ON state. In this case, the resistance value of the variable resistor 11 is the resistance value of the parallel connection of the resistor RgSC1 and the P-channel MOSFET having an ON resistance. Therefore, the resistance value of the variable resistor 11 is smaller than the resistance value of the resistor RgSC1.

[0038] Even when the gate is biased to a positive voltage, if the voltage between the gate terminal Gp1 and the source terminal Sp1 is lower in the negative direction than the threshold voltage VthQp1 (negative value) of the P-channel MOSFET Qp1, the P-channel MOSFET Qp1 is in the off state. In this case, the resistance value of the variable resistor 11 becomes the resistance RgSC1.

[0039] When the switching element SW1 is in the off state, a negative gate voltage bias is applied, and the parasitic diode (body diode) of the P-channel MOSFET Qp1 is conductive, so that the resistance value of the variable resistor 11 is smaller than the resistance value of the resistor RgSC1. Therefore, the effect of the variable resistor 11 on the turn-off characteristics of the switching element SW1 is small.

[0040] As described above, the resistance value of the variable resistor 11 changes depending on the gate bias state of the switching element SW1. Therefore, the resistance value can be controlled without using a dedicated control wiring. In the first embodiment, the gate terminal Gp1 of the P-channel MOSFET Qp1 is connected to the emitter terminal E1 of the switching element SW1, and the variable resistor 11 does not have a dedicated control wiring for controlling the resistance value.

[0041] Instead of the P-channel MOSFET Qp1, an IGBT or a junction bipolar transistor may be used. A diode is connected in anti-parallel to the IGBT or the junction bipolar transistor to bypass the off-gate current, similar to the parasitic diode of Qp1. The circuit configuration of the variable resistor is not limited to the circuit configuration shown in FIG. 2, and other circuit configurations may be used in which the resistance value changes according to the gate bias state of the switching element SW1.

[0042] 3 is a time chart showing the operation of the power semiconductor module of Example 1. The figure shows the operating state of the variable resistor and the upper arm when the inductive load 7 (FIG. 1) is short-circuited.

[0043] From the top in Figure 3, the collector-emitter voltage VceH, the collector current IcH, the gate voltage VgeH, and the internal gate voltage VgeH int , the on / off state of the switching element SW1, the on / off state of the switching element Q1, the resistance value Rg of the variable resistor 11 vari1 (For current and current see Figure 1.)

[0044] Although not shown, a short circuit occurs in the inductive load 7 at time t1.

[0045] At time t1, the inductive load 7 is short-circuited, but the switching element SW1 is in the off state, so the collector current IcH does not flow. In addition, because the gate voltage VgeH is a negative voltage bias, the parasitic diode of the P-channel MOSFET Qp1 in the variable resistor 11 is in a conductive state. Therefore, the resistance value Rg of the variable resistor 11 vari1 has a resistance value lower than RgSC1 (hereinafter referred to as "low resistance value").

[0046] At time t2, the gate voltage VgeH transitions from a negative voltage bias to a positive voltage bias, so that the parasitic diode of the P-channel MOSFET Qp1 is turned off. In addition, during the period b from time t2 to time t3, even if the gate voltage VgeH is a positive voltage bias, the threshold voltage Vth Qp1 (In FIG. 3, for convenience, it is a positive value.) Therefore, in the period b, the P-channel MOSFET Qp1 is in the off state, and the resistance value Rg of the variable resistor 11 vari1 has the same resistance value as the resistor RgSC1 (hereinafter referred to as "high resistance value").

[0047] At time t3, the gate voltage VgeH becomes equal to the threshold voltage Vth Qp1 Therefore, the resistance value Rg of the variable resistor 11 increases to 1.0 V, and the P-channel MOSFET Qp1 is turned on. vari1 Here, the internal gate voltage VgeH of the switching element SW1 int is the threshold voltage Vth of the switching element SW1 sw1 Therefore, during the gate delay period before the switching element SW1 is turned on, the P-channel MOSFET Qp1 is turned on and the resistance value Rg of the variable resistor 11 is increased. vari1 This causes the switching element SW1 to switch the resistance Rg vari1Since the transistor turns on when it has a low resistance value, an increase in turn-on time and turn-on loss during normal switching can be prevented.

[0048] At time t4, the internal gate voltage VgeH of the switching element SW1 int is the threshold voltage Vth of the switching element SW1 sw1 As a result, the switching element SW1 is turned on. At this time, since the inductive load 7 is short-circuited, the smoothing capacitor 6, which is charged to the DC power supply voltage Vcc by the DC power supply 1, is short-circuited with low impedance. As a result, a short-circuit current starts to flow through the switching element SW1.

[0049] At time t5, the comparator 15 detects the short circuit and switches the switching element Q1 from the OFF state to the ON state. As a result, the Zener diode 16 is inserted between the gate auxiliary terminal G1AUX and the emitter auxiliary terminal E1AUX, and the gate voltage VgeH starts to decrease toward the breakdown voltage of the Zener diode 16. Here, the breakdown voltage of the Zener diode 16 is equal to the threshold voltage Vth of the switching element SW1. sw1 This is set to be higher than the positive power supply voltage Vgep1 of the gate drive circuit 36. Therefore, after the current IcH flowing through the switching element SW1 is reduced to a certain extent, the short-circuit current is cut off by the short-circuit protection function of the gate drive circuit 36. This makes it possible to suppress the generation of an excessive surge voltage accompanying the cutting off of the short-circuit current.

[0050] At time t6, the gate voltage VgeH becomes equal to the threshold voltage Vth Qp1 Therefore, the resistance value Rg of the variable resistor 11 becomes lower than the threshold voltage Vp1, and the P-channel MOSFET Qp1 transitions from the ON state to the OFF state. vari1 changes from a low resistance value to a high resistance value. As a result, the variable resistor 11 becomes a damping resistor, and the oscillation of the gate voltage VgeH (gate voltage waveform VgeH shown by the dashed line in FIG. 3) that occurs when the short-circuit current is reduced and cut off is eliminated. w / odamp See below) is suppressed.

[0051] At time t7, the short-circuit protection function of the gate drive circuit 36 ​​is activated, turning off the switching element SW1.

[0052] At time t8, the short-circuit current is cut off. After time t8, the gate voltage VgeH becomes a negative gate voltage bias, so that the resistance value Rg vari1 returns from a high resistance value to a low resistance value.

[0053] The resistance value of the variable resistor 11 according to the first embodiment changes depending on the gate voltage VgeH, i.e., the gate bias state of the switching element SW1. In this case, the variable resistor 11 is controlled in the module using the gate voltage VgeH as a control power supply. Note that the gate voltage VgeH is output by the gate drive circuit 36 ​​using a control power supply provided in the gate drive circuit 36, so to speak, the control power supply provided in the gate drive circuit 36 ​​also serves as the control power supply for the variable resistor 11. Therefore, the resistance value of the variable resistor 11 can be controlled without using a dedicated control wiring.

[0054] In the first embodiment (FIG. 2), the gate terminal Gp1 of the P-channel MOSFET Qp1 is connected to the emitter terminal E1 of the switching element SW1, and the variable resistor 11 does not have a dedicated control wiring for controlling the resistance value. In the first embodiment (FIG. 3), the variable resistance value is switched from a low resistance value to a high resistance value in response to the gate voltage VgeH decreasing from Vgep1 (t5 to t6 in FIG. 3).

[0055] Furthermore, in the variable resistor 11 according to the first embodiment, from when the switching element SW1 is turned on to when it is turned off (see t4 to t8 in FIG. 3), the gate voltage VgeH is equal to or lower than the threshold voltage Vth SW1 When the gate voltage is higher and lower than a predetermined value of the gate voltage VgeH (the positive power supply voltage Vgep1 of the gate drive circuit 36 ​​in the first embodiment), the resistance value becomes larger than when the gate voltage is at the predetermined value.

[0056] This makes it possible to prevent gate voltage oscillation while suppressing an increase in switching loss due to gate resistance.Furthermore, it is possible to prevent the occurrence of an excessive surge voltage at turn-off.Furthermore, in the event of a short circuit, the short circuit resistance of the switching element can be improved by lowering the gate voltage to suppress the magnitude of the short circuit current. EXAMPLES

[0057] Next, a second embodiment of the present invention will be described with reference to Fig. 4. The differences from the first embodiment will be mainly described.

[0058] Second Embodiment FIG. 4 is a circuit diagram showing a configuration of a power semiconductor module according to a second embodiment of the present invention.

[0059] In the second embodiment, the upper arm includes an upper arm first substrate 46 having switching element SW1a and diode 37 mounted thereon, and an upper arm second substrate 47 having switching element SW1b and diode 38 mounted thereon. The lower arm includes a lower arm first substrate 48 having switching element SW2a and diode 39 mounted thereon, and a lower arm second substrate 49 having switching element SW2b and diode 40 mounted thereon.

[0060] The upper arm first substrate 46 and the upper arm second substrate 47 are connected in parallel by connecting between collector terminal C1a and collector terminal C1b and between output terminal AC1a and output terminal AC1b, respectively, outside the module. The lower arm first substrate 48 and the lower arm second substrate 49 are connected in parallel by connecting between output terminal AC1a and output terminal AC1b and between emitter terminal E2a and emitter terminal E2b, respectively, outside the module. This makes it possible to increase the rated current of the power semiconductor module.

[0061] The gate auxiliary terminal G1AUX and emitter auxiliary terminal E1AUX of the upper arm are common to the upper arm first board 46 and the upper arm second board 47, and the wiring branches off inside the module. The gate auxiliary terminal G2AUX and emitter auxiliary terminal E2AUX of the lower arm are common to the lower arm first board 48 and the lower arm second board 49, and the wiring branches off inside the module.

[0062] According to such a module configuration, a gate-emitter loop is formed between the parallel substrates, such as current path 50 and current path 51 shown in Fig. 4. For this reason, in the event of a short circuit, an oscillating current may flow through current path 50 or current path 51 between the parallel substrates, causing gate voltage oscillation.

[0063] Therefore, in the second embodiment, in the upper arm, variable resistors 41 and 42 are inserted between a branch point 52 where the gate wiring branches in the module and the gate terminal G1a of the switching element SW1a, and between the branch point 52 and the gate terminal G1b of the switching element SW1b, respectively. In the lower arm, variable resistors 43 and 44 are inserted between a branch point 53 and the gate terminal G2a of the switching element SW2a, and between the branch point 53 and the gate terminal G2b of the switching element SW2b, respectively.

[0064] The configuration of the variable resistors 41, 42, 43, and 44 is the same as that of the variable resistor 11 described in Fig. 2 of the first embodiment, and therefore a description thereof will be omitted. The variable resistors 41 and 42 serve as damping resistors in a current path 50, and the variable resistors 43 and 44 serve as damping resistors in a current path 51. This makes it possible to prevent gate voltage oscillation when a plurality of switching elements included in the power semiconductor module 8 are connected in parallel and have a common auxiliary terminal (auxiliary gate terminal, auxiliary emitter terminal).

[0065] Since each of the multiple switching elements connected in parallel has a variable resistor, the multiple switching elements are switched on and off uniformly, ensuring reliability of the parallel operation. EXAMPLES

[0066] Next, a third embodiment of the present invention will be described with reference to FIGS.

[0067] FIG. 5 is a schematic diagram showing the external appearance of a power semiconductor module according to a third embodiment of the present invention.

[0068] The circuit configuration of the power semiconductor module 8 is the same as that of the above-described embodiment 2 (FIG. 4). That is, the power semiconductor module 8 is a so-called 2-in-1 module that includes two half-bridge circuits each having an upper arm and a lower arm connected in series.

[0069] The power semiconductor module 8 is a so-called insulated power semiconductor module.

[0070] As described below, the two upper arms, the two lower arms, and the variable resistors connected to each arm are mounted on a metal base 101. The entire surface of the metal base 101 is covered with a resin case 102. The resin case 102 is joined to the metal base 101.

[0071] On the upper surface of the resin case 102, the connection portions of a plurality of electrode terminals drawn from the circuit portion on the metal base 101 to external wiring are exposed. In the present embodiment 3, these electrode terminals are a plurality of main terminals and a plurality of auxiliary terminals. The plurality of main terminals are a collector terminal C1, an emitter terminal E2, and an output terminal AC drawn from each of the two half-bridge circuits. The auxiliary terminals are an auxiliary gate terminal G1AUX, an auxiliary emitter terminal E1AUX, and an auxiliary collector terminal C1AUX that are common to the two upper arms, and an auxiliary gate terminal G2AUX, an auxiliary emitter terminal E2AUX, and an auxiliary collector terminal C2AUX that are common to the two lower arms.

[0072] The output terminal AC is electrically connected within the resin case 102 to the emitter terminal E1 of the upper arm and the collector terminal C2 of the lower arm.

[0073] By connecting the two collector terminals C1 together, the two emitter terminals E2 together, and the two output terminals AC together by external wiring, the two upper arms are connected in parallel and the two lower arms are connected in parallel, as in the above-described second embodiment.

[0074] The auxiliary gate terminal G1AUX and the auxiliary emitter terminal E1AUX are connected to a gate drive circuit for the upper arm, and the auxiliary gate terminal G2AUX and the auxiliary emitter terminal E2AUX are connected to a gate drive circuit for the lower arm. The auxiliary collector terminals C1AUX and C2AUX are used for short circuit detection.

[0075] The above-described module configuration is substantially the same as that of a known power semiconductor module.

[0076] FIG. 6 is a schematic diagram showing an internal configuration of a power semiconductor module according to a third embodiment.

[0077] As shown in Fig. 6, insulating circuit boards 111, 113, 121-124 are placed and joined on the surface of metal base 101. Note that Fig. 6 only shows the arrangement of the insulating circuit boards, and does not show the configuration of circuit elements such as switching elements, electrodes, and wiring.

[0078] Insulated circuit board 121, insulated circuit board 122, insulated circuit board 123 and insulated circuit board 124 correspond to upper arm first board 46, lower arm first board 48, upper arm second board 47 and lower arm second board 49 in Example 2 (FIG. 4), respectively. Variable resistors 41 and 42 for the upper arm in Example 2 (FIG. 4) are configured on insulating circuit board 111. Variable resistors 43 and 44 for the lower arm in Example 2 (FIG. 4) are configured on circuit board 113.

[0079] According to the third embodiment, it is possible to suppress gate voltage oscillation without significantly changing the module configuration. EXAMPLES

[0080] Next, a fourth embodiment of the present invention will be described with reference to FIG.

[0081] Fourth Embodiment FIG. 7 is a circuit diagram showing the configuration of a motor drive system according to a fourth embodiment of the present invention.

[0082] As shown in FIG. 7, in a motor drive system 61, a motor 58 is driven by AC power output by a power conversion device 60.

[0083] The power conversion device 60 includes a three-phase inverter main circuit configured with three power semiconductor modules 8 (2-in-1 module) each having a pair of upper and lower arms, a DC power supply 1 connected to the DC side of the three-phase inverter main circuit, a gate drive circuit 36 ​​that drives the power semiconductor modules 8, and a controller 54 that outputs a PWM signal to the gate drive circuit 36.

[0084] Any of the above-described embodiments 1 to 3 is applied as the power semiconductor module 8. The motor 58 is a three-phase AC motor, and each phase of the motor 58 is connected to an output terminal (for example, "AC" in FIG. 1) of the power semiconductor module.

[0085] The controller 54 calculates two PWM signals (S1i to S2i: i=u, v, w) for each phase based on the three-phase currents (Iu, Iv, Iw) of the motor 58 detected by the current sensors (55, 56, 57) and the rotation speed (ω) of the motor 58 detected by the speed detector 59, and outputs the signals to the gate drive circuit 36 ​​for each phase. The power semiconductor modules 8 are switched by the gate drive circuit 36 ​​in response to the PWM signals, whereby the DC power from the DC power supply 1 is converted into three-phase AC power. The motor 58 is driven by this three-phase AC power.

[0086] By applying any one of the above-mentioned Examples 1 to 3 as the power semiconductor module 8, it is possible to prevent gate voltage oscillation during a short circuit and reduce loss during normal switching without the need for dedicated control wiring for the variable resistor. This allows the power conversion device 60 and the motor drive system 61 to be miniaturized. Furthermore, since the short circuit current can be suppressed by the drop in gate voltage during a short circuit, it is possible to increase the short circuit resistance of the power semiconductor module 8 and improve reliability. This improves the reliability of the motor drive system.

[0087] The present invention is not limited to the above-described embodiments, and includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0088] For example, the conductivity type of the channel of the insulated gate switching element in the arm may be different from that of the above embodiment (n-channel IGBT). In this case, the positive and negative of the gate power supply voltage and the gate threshold voltage are reversed from those of the above embodiment.

[0089] The power semiconductor module may be a resin mold type, or may be a so-called IPM (Intelligent Power Module) that includes a gate circuit and the like. [Explanation of symbols]

[0090] 1 DC power supply 2,3,4,5 Wiring 6 Smoothing capacitor 7 Inductive load 8 Power Semiconductor Modules 10,12 Diode 11,13 Variable resistor 14,25 Short circuit detection reference potential 15,26 Comparator 16,27 Zener diode 17,18 DC power supply 19,20 Smoothing capacitor 21,24 Switching elements 28,29 DC power supply 30,31 Smoothing capacitor 32,35 Switching elements 36 Gate drive circuit 37, 38, 39, 40 Diodes 41, 42, 43, 44 Variable resistor 46 First board of upper arm 47 Second board of upper arm 48 First board of lower arm 49 Second board of lower arm 50,51 Current path 52,53 Branching point 54 Controller 55,56,57 Current Sensors 58 Motor 59 Speed ​​Detector 60 Power conversion device 61 Motor Drive System 101 Metal Base 102 Resin case 111,113,121,122,123,124 Insulated circuit board

Claims

1. A switching element; a gate resistor connected to a gate of the switching element; In a power semiconductor module having the gate resistor is a variable resistor whose resistance value becomes larger when a gate voltage output from a gate drive circuit that drives the switching element is higher than a threshold voltage of the switching element and lower than a predetermined threshold value that is lower than the predetermined value of the gate voltage, compared to when the gate voltage is at the predetermined value; A power semiconductor module characterized in that, when a short-circuit current flows through the switching element, the gate voltage begins to decrease toward a voltage lower than the predetermined threshold, and becomes higher than the threshold voltage of the switching element and lower than the predetermined threshold.

2. 2. The power semiconductor module according to claim 1, A power semiconductor module, characterized in that a resistance value of the gate resistor is controlled by the gate voltage, and the predetermined value of the gate voltage is a voltage value of a control power supply provided in the gate drive circuit.

3. 2. The power semiconductor module according to claim 1, a gate resistor connected in parallel to the resistor, a high potential side of the gate voltage being connected to a source of the P-channel MOSFET, a gate of the P-channel MOSFET being connected to an emitter or a source of the switching element, and a drain of the P-channel MOSFET being connected to a gate of the switching element.

4. A first switching element; A second switching element; a first gate resistor connected to a gate of the first switching element; a second gate resistor connected to a gate of the second switching element; having In a power semiconductor module, the first switching element and the second switching element are configured to be connectable in parallel by external wiring, a gate drive circuit is connected to an auxiliary terminal common to the first switching element and the second switching element; the first gate resistor is connected between the gate of the first switching element and the auxiliary terminal; the second gate resistor is connected between the gate of the second switching element and the auxiliary terminal; the first gate resistor is a variable resistor whose resistance value is larger when a first gate voltage output from the gate drive circuit that drives the first switching element is lower than a first predetermined threshold value that is higher than a threshold voltage of the first switching element and lower than a first predetermined value of the first gate voltage, compared to when the first gate voltage is the first predetermined value; the second gate resistor is a variable resistor whose resistance value becomes larger when a second gate voltage output from the gate drive circuit that drives the second switching element is lower than a second threshold value that is higher than a threshold voltage of the second switching element and lower than a second predetermined value of the second gate voltage, compared to when the second gate voltage is at the second predetermined value; When a short circuit current flows through the first switching element, the first gate voltage starts to decrease toward a voltage lower than the predetermined first threshold, and becomes higher than a threshold voltage of the first switching element and lower than the predetermined first threshold; When a short-circuit current flows through the second switching element, the second gate voltage begins to decrease toward a voltage lower than the predetermined second threshold, and becomes higher than the threshold voltage of the second switching element and lower than the predetermined second threshold.

5. The power semiconductor module according to claim 1, further comprising: a case for housing the switching element and the gate resistor; an auxiliary terminal exposed from the case and connected to the gate drive circuit; A power semiconductor module comprising:

6. 2. The power semiconductor module according to claim 1, A power semiconductor module comprising: a Zener diode having a breakdown voltage set to be higher than the threshold voltage of the switching element and lower than the predetermined threshold voltage, when a short-circuit current flows through the switching element, such that the gate voltage begins to decrease toward a voltage lower than the predetermined threshold voltage.

7. In a motor drive system including a power conversion device that drives a motor, A main circuit of the power conversion device is constituted by a power semiconductor module, A motor drive system, wherein the power semiconductor module is the power semiconductor module according to claim 1.

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