JP2007143336A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a voltage oscillation generated in a snubber circuit for absorbing a surge voltage due to a switching operation of a semiconductor switching element, and prevent the semiconductor element from being damaged. <P>SOLUTION: The voltage generated by the snubber circuit is detected. A phase of the voltage oscillated due to the switching operation is detected. Timing of the switching operation is controlled so as to prevent the voltage oscillation from being superimposed in phase. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor device used in a power conversion device such as an inverter device or a converter device.

FIG. 6 is a diagram showing a conventional example of a semiconductor device. In FIG. 6, 31 and 32 are semiconductor switch elements, and here, IGBTs (insulated gate bipolar transistors) are used. Reference numerals 41 and 42 denote diodes connected to the semiconductor switch elements 31 and 32 in antiparallel, respectively. Reference numerals 610 and 620 denote drive circuits for driving the semiconductor switch elements 31 and 32. Based on switching signals L1 and L2 from the outside, signals for controlling on / off of the semiconductor switch elements 31 and 32 are sent to the semiconductor switch elements 31 and 32. To the gate terminal.
In the drive circuit 610, reference numeral 611 denotes a MOSFET (metal oxide field effect transistor) that also serves as an on-gate resistance, and 612 denotes a MOSFET that also serves as an off-gate resistance. When the external switching signal L1 becomes H (high), the MOSFET 611 is turned on, a voltage is applied from the external drive circuit power supply 71 to the gate of the semiconductor switch element 31 via the MOSFET 31, and the semiconductor switch element 31 is turned on. Further, when the switching signal L1 becomes L (low), the MOSFET 612 inputted by inverting this signal is turned on, no voltage is applied to the gate of the semiconductor switch element 31, and the semiconductor switch element 31 is turned off. Since the gate driving circuit 620 operates in the same manner as the gate driving circuit 610, detailed description thereof is omitted.

Reference numeral 5 denotes a snubber circuit composed of a capacitor 51, which is connected to both ends of a series circuit of semiconductor switches 31 and 32. A snubber circuit is connected as close as possible to the series circuit of the semiconductor switch elements 31 and 32.
The semiconductor switch elements 31 and 32 are connected in series, and both ends thereof are connected to the DC power source 1. As a power conversion device for obtaining a desired voltage from the connection point (output terminal) of the semiconductor switch elements 31 and 32 by controlling the semiconductor switch elements 31 and 32 to be turned on and off based on the switching signals L1 and L2. Can be used. As such a structure, the thing of patent document 1 is known.
Here, the semiconductor switch elements 31 and 32 and the drive circuits 61 and 62 may be stored in one package and configured as an IPM (Intelligent Power Module).
JP 10-66356 A (summary etc.)

In the conventional example shown in FIG. 6, a snubber circuit 5 including a capacitor 51 is connected to both ends of a series circuit of the semiconductor switch elements 31 and 32 in order to absorb a surge voltage during the switching operation of the semiconductor switch elements 31 and 32. ing. The capacity of the snubber circuit 5 (capacitor 51) is determined according to the current flowing through the semiconductor switch elements 31 and 32.
When the current flowing through the semiconductor switch elements 31 and 32 increases, the surge voltage associated with the switching of the semiconductor switching element increases, so that the capacity of the capacitor 51 for absorbing this is set large, but the capacity of the capacitor 51 increases. Then, the volume of the capacitor 51 also increases. For this reason, when a semiconductor device is used as a power conversion device, the power conversion device is increased in size by a large capacitor, which causes problems such as difficulty in installation in a narrow space.

Further, a parasitic inductance 52 exists in the wiring between the snubber circuit 5 and the semiconductor switch elements 31 and 32 and the capacitor 51, and the resonance between the capacitor 51 and the parasitic inductance 52 causes a switching operation as shown in FIG. The voltage between the terminals of the snubber circuit vibrates (hereinafter, this vibration is referred to as snubber vibration). As shown in FIG. 7B, when the next switching operation is performed while this vibration remains, surge voltage or snubber vibration is superimposed, and the voltage applied to both ends of the semiconductor switch elements 31 and 32 is applied to the semiconductor switch. The breakdown voltage of the elements 31 and 32 may be exceeded, and the semiconductor switch elements 31 and 32 may be destroyed.
Therefore, as a countermeasure,
(1) The switching interval is expanded to limit the switching after the amplitude of the snubber vibration is reduced.
(2) Increase the capacity of the capacitor 51 to reduce the amplitude of the snubber vibration.
(3) Shorten the wiring distance to reduce the amplitude of the snubber vibration.
Measures such as are taken.

However, if the switching interval is increased as in (1), the responsiveness of the circuit is reduced, and if the capacitor capacity is increased as in (2), it is difficult to reduce the size of the device, and the wiring distance is increased as in (3). When shortening, each problem is unavoidable, such as the degree of freedom of component placement decreasing.
Although it is possible to change the snubber circuit format and suppress snubber vibration using other parts such as a diode, the circuit configuration becomes complicated and the number of parts increases. Further, in order to apply to a semiconductor device used in a high temperature environment or a high voltage, an expensive part with a high withstand voltage is required, which causes an increase in cost.
The present invention solves the above problems and provides a semiconductor device capable of preventing the semiconductor switching element from being destroyed.

In order to solve the above-described problems, the present invention provides a semiconductor device including a semiconductor switch element, a drive circuit that drives the semiconductor switch element, and a snubber circuit that suppresses a surge voltage generated when the semiconductor switch element is switched. The voltage detection circuit for detecting the voltage across the snubber circuit and the phase detection circuit for detecting the phase of the vibration component of the detection signal output from the voltage detection circuit, wherein the drive circuit includes the phase detection circuit The timing of the switching operation of the semiconductor switch is controlled based on the output of
In the above, the phase detection circuit detects a phase of voltage oscillation caused by the switching from a detection signal output from the voltage detection circuit, and the drive circuit detects the vibration based on the output of the phase detection circuit. The switching operation timing of the semiconductor switch is controlled so that the phases of the components are not superimposed in the same phase.

In addition, in a semiconductor device comprising a semiconductor switch element, a drive circuit that drives the semiconductor switch element, and a snubber circuit that suppresses a surge voltage generated when the semiconductor switch element is switched, the voltage across the snubber circuit is detected. And a vibration detection circuit that detects an amplitude of a vibration component of a detection signal output from the voltage detection circuit, and the drive circuit is configured to output the semiconductor switch based on the output of the vibration detection circuit. It is assumed that the timing of the switching operation is controlled.
In the above, the drive circuit is configured to control the timing to perform the switching operation of the semiconductor switch when the amplitude of the vibration component is smaller than a predetermined value based on the output of the phase detection circuit.
In addition, in a semiconductor device comprising a semiconductor switch element, a drive circuit that drives the semiconductor switch element, and a snubber circuit that suppresses a surge voltage generated when the semiconductor switch element is switched, the voltage across the snubber circuit is detected. Voltage detection circuit that detects the phase of the vibration component of the detection signal output from the voltage detection circuit, and a vibration detection circuit that detects the amplitude of the vibration component of the detection signal output from the voltage detection circuit And the driving circuit is configured to prevent the phase of the vibration component from being superimposed on the same phase when the amplitude of the vibration component is smaller than a predetermined value based on the output of the phase detection circuit. It is assumed that the timing of the switching operation is controlled.

  Further, in any of the above-described configurations, the semiconductor switch element, the drive circuit, the voltage detection circuit, and either or both of the phase detection circuit and the vibration detection circuit are stored in the same package. And

  As described above, according to the present invention, even when the switching operation and the surge voltage or the snubber vibration are superimposed, the amplitude of the snubber vibration is not increased, and the semiconductor switching element can be prevented from being broken. Further, the capacity of the capacitor used for the snubber circuit can be reduced, and the semiconductor device can be reduced in size.

The present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of a first embodiment of the present invention. In FIG. 1, 1 is a DC power source and 2 is an IPM. The IPM 2 includes semiconductor switch elements 31, 32 such as IGBTs, diodes 41, 42 connected in reverse parallel to the semiconductor switch elements 31, 32, and drive circuits 61, 62 for driving the semiconductor switch elements 31, 32, respectively. It has.
11 is a voltage detection circuit for detecting the voltage between the terminals of the snubber circuit 5, 12 is a phase detection circuit for detecting the phase of the vibration component of the voltage signal from the voltage detection circuit, and 131 and 132 are detection results and switching signals of the phase detection circuit. This is a switching control circuit that controls the timing of the switching operation of the semiconductor switch elements 31 and 32 based on L1 and L2 and outputs them as switching signals L1 ′ and L2 ′. As for the switching control circuits 131 and 132, a voltage detection circuit 11 and a phase detection circuit 12, which will be described later, are stored in the IPM2, and the switching control circuits 131 and 132 are stored in the IPM2 as part of the drive circuits 61 and 62.

A snubber circuit 5 composed of a capacitor 51 is connected in parallel to both ends of a series connection circuit of the semiconductor switch elements 31 and 32. The snubber circuit 5 is preferably provided in the vicinity of the semiconductor switching elements 31 and 32 in order to suppress the parasitic inductance of the wiring. The capacitor 51 of the snubber circuit 5 is often a large component and is often externally attached to the IPM 2 in consideration of convenience of replacement.
In FIG. 1, the wiring connecting the voltage detection circuit 11 and both ends of the snubber circuit 5 is connected from the outside of the IPM 2 to the inside of the IPM 2 for convenience of illustration, but the voltage detection circuit 11 is stored in the IPM 2. If it is, it is preferable that the wiring is performed in the IPM 2 so as to detect the voltage across the series circuit of the semiconductor switch elements 31 and 32. This is because the semiconductor switch element 31 and one end of the snubber circuit 5 are connected to the high potential side of the DC power supply 1 and the voltage detection value is a signal having the high potential side as a reference potential. This is because wiring within the IPM 2 that is insulated from each other is preferable for insulation and noise countermeasures.

In the gate drive circuit 61, the switching signal L 1 is input to the switching control circuit 131, and the switching signal L 1 ′ whose switching timing is controlled based on the output of the phase detection circuit 12 is guided to the gates of the MOSFETs 611 and 612.
Similarly, in the gate drive circuit 62, the switching signal L 2 is input to the switching control circuit 132 and becomes a switching signal L 2 ′ whose switching timing is controlled based on the output of the phase detection circuit 12, and is applied to the gates of the MOSFETs 621 and 622. Led.
Since the semiconductor switch element 31 is turned on / off by the MOSFETs 611, 612 and the semiconductor switch element 32 is turned on / off by the MOSFETs 621, 622, the detailed description is omitted.

Next, switching timing control by the switching control circuits 131 and 132 will be described using the switching control circuit 131 (switching signal L1) as an example. FIG. 2 is a diagram showing waveforms at various parts in the configuration of FIG.
As shown in FIG. 2A, snubber vibration occurs in the voltage between the terminals of the snubber circuit 5 (detected value of the voltage detection circuit 11) by turning on and off the semiconductor switch element 31. Snubber vibration is generated by resonance between the capacitor 51 of the snubber circuit and the parasitic inductance 52 of the snubber circuit.
When the next switching operation (for example, off) is performed before the snubber vibration generated by the switching operation (for example, on) of the semiconductor switching element 31 is not sufficiently attenuated, the switching operation is performed at a timing at which the snubber vibration is superimposed in the opposite phase. For example, the snubber vibration cancels out and the vibration amplitude does not increase.

Therefore, the phase detection circuit 12 detects the phase of the snubber vibration. The phase detection circuit 12 outputs a signal that becomes H (high) or L (low) when the phase of the snubber vibration reaches a predetermined value. In the example of FIG. 2, when the snubber vibration rises with reference voltage (0 [V]) as a reference, the phase is 0 degree, and when it falls, the zero cross (reference voltage) time is 180 degrees, and again rises to zero cross. In the example, the time of (reference voltage) is one cycle of phase 360 degrees (0 degrees), and changes to H when the phase is 0 degrees and changes to 0 when the phase is 180 degrees.
FIG. 3 is a diagram illustrating an example of the configuration of the switching control circuit 131. Symbols in parentheses correspond to the waveforms (B), (C), and (D) in FIG.
The switching control circuit 131 of the gate drive circuit 61 includes an AND gate 1311 and a flip-flop 1312, and inputs the switching signal L 1 (B) and the inverted signal of the detection signal (C) of the phase detection circuit 12 to the AND gate 1311. Therefore, the flip-flop 1312 is set at the timing when the switching signal L1 is H and the detection signal of the phase detection circuit 12 is L, and the H switching signal L1 ′ (D) is output from the terminal Q. As described above, when the switching signal L1 ′ becomes H, the MOSFET 611 is turned on and the semiconductor switch element 31 is turned on.

When the switching signal L1 (B) becomes H (time t1 in FIG. 2) by such a switching control circuit 131, the phase detection signal (C) is H, that is, the timing at which the snubber vibration is superimposed in the same phase. Then, the switching signal L1 ′ (D) is L, the semiconductor switch element 31 is not turned on, and the phase detection signal (C) is L, that is, switching is performed at the timing when the snubber oscillation is in the opposite phase (time t2 in FIG. 2). The signal L1 ′ (D) becomes H, and the semiconductor switch element 31 is turned on.
Further, since the inverted signal of the switching signal L1 (B) is input to the reset terminal of the flip-flop, when the switching signal L1 becomes L (time t3 in FIG. 2), the switching signal L1 ′ (D) is L Thus, the semiconductor switch element 31 is turned off.
Up to this point, the switching control circuit 131 has been described. Similarly, the switching control circuit 132 also applies the switching signal L2 ′ from the phase detection signal (C) and the switching signal L2 so that the snubber vibration does not overlap in the same phase. It only has to be generated.

The semiconductor switch elements 31 and 32 operate with different reference potentials. That is, the semiconductor switch element 31 operates with a control signal having a high potential side as a reference potential, and the semiconductor switch element 32 operates with a control signal having a low potential (GND potential) as a reference potential. When the reference potential of the voltage detection circuit or the phase detection circuit is different from that of the switching control circuits 131 and 132, when the signal is transmitted to a circuit having a different reference potential, the level of the reference potential is adjusted through a level shift circuit or the like. Good. For example, when the phase detection circuit is based on a high potential, a level shift circuit may be provided at the input stage of the phase detection signal of the switching control circuit 132.
By configuring as described above, it is possible to prevent the snubber vibration from being superordinated in the same phase for each switching operation, and it is possible to prevent the semiconductor switch element from being destroyed by the snubber vibration.

FIG. 4 is a configuration diagram of the second embodiment. The difference from FIG. 1 is that the phase detection circuit 12 is replaced with an amplitude detection circuit 14. The amplitude detection circuit 14 outputs H when the amplitude of the snubber vibration is below a certain value, and the switching control circuits 131 and 132 turn on and off the MOSFETs 611 and 612 only when the output of the amplitude detection circuit 14 is H. Operate. Thereby, since the switching operation is performed only when the snubber vibration is small, it is possible to prevent the influence due to the vibration superposition.
FIG. 5 is a block diagram of the third embodiment. The difference from FIG. 1 is that a phase detection circuit 12 and an amplitude detection circuit 14 are further provided. The switching control circuits 131 and 132 operate so as to turn on and off the MOSFETs 611 and 612 only when the output of the phase detection circuit 12 changes, the output of the amplitude detection circuit 14 is H, and the output of the phase detection circuit 12 changes. . As a result, if the signal amplitude is equal to or less than a certain value, the switching operation is performed so as to have an opposite phase, so that the influence of vibration superposition can be prevented.

The IPM has been described above as an example, but is not limited to the IPM. For example, the present invention can be applied to a configuration in which the switching control circuits 131 and 132, the voltage detection circuit 11 and the phase detection circuit 13 are externally attached to a power semiconductor module in which only the semiconductor switch elements 32 and 32 are stored in the same package.
Moreover, each said form is applicable to various power converter devices. For example, a power converter (for example, a bidirectional step-up / step-down DC-DC converter) having a mode in which the semiconductor switch elements 31 and 32 perform switching alone is suitable for application because the snubber vibration is not complicated. .
Further, the present invention can be applied to a power conversion device such as an inverter device in which a plurality of sets of series circuits of semiconductor switch elements 31 and 32 are connected in parallel and the semiconductor switch elements 31 and 32 are alternately switched.

It is a block diagram of 1st Embodiment. It is a figure which shows the waveform of each part in the structure of FIG. It is a figure which shows the structure of a switching control circuit. It is a block diagram of 2nd Embodiment. It is a block diagram of 3rd Embodiment. It is a figure which shows a prior art example. It is a figure which shows the waveform of each part in a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... DC power supply, 2 ... IPM, 5 ... Snubber circuit, 11 ... Voltage detection circuit, 12 ... Phase detection circuit, 131, 131 ... Switching control circuit, 14 ... Amplitude detection circuit, 31, 32 ... Semiconductor switch element, 61, 62, 610, 620... Gate drive circuit.

Claims (6)

In a semiconductor device comprising a semiconductor switch element, a drive circuit that drives the semiconductor switch element, and a snubber circuit that suppresses a surge voltage generated when the semiconductor switch element is switched,
A voltage detection circuit for detecting a voltage across the snubber circuit;
A phase detection circuit for detecting the phase of the vibration component of the detection signal output from the voltage detection circuit,
The drive circuit controls the timing of the switching operation of the semiconductor switch based on the output of the phase detection circuit. The semiconductor device according to claim 1,
The phase detection circuit detects a phase of voltage oscillation caused by the switching from a detection signal output from the voltage detection circuit,
The drive circuit controls the switching operation timing of the semiconductor switch based on the output of the phase detection circuit so that the phase of the vibration component is not superimposed on the same phase. In a semiconductor device comprising a semiconductor switch element, a drive circuit that drives the semiconductor switch element, and a snubber circuit that suppresses a surge voltage generated when the semiconductor switch element is switched,
A voltage detection circuit for detecting a voltage across the snubber circuit;
A vibration detection circuit that detects the amplitude of the vibration component of the detection signal output from the voltage detection circuit;
The drive circuit controls a switching operation timing of the semiconductor switch based on an output of the vibration detection circuit. The semiconductor device according to claim 3.
The drive circuit controls the timing to perform the switching operation of the semiconductor switch when the amplitude of the vibration component is smaller than a predetermined value based on the output of the phase detection circuit. In a semiconductor device comprising a semiconductor switch element, a drive circuit that drives the semiconductor switch element, and a snubber circuit that suppresses a surge voltage generated when the semiconductor switch element is switched,
A voltage detection circuit for detecting a voltage across the snubber circuit;
A phase detection circuit for detecting the phase of the vibration component of the detection signal output from the voltage detection circuit;
A vibration detection circuit that detects an amplitude of a vibration component of a detection signal output from the voltage detection circuit;
When the amplitude of the vibration component is smaller than a predetermined value based on the output of the phase detection circuit, the drive circuit performs a switching operation of the semiconductor switch so that the phase of the vibration component is not superimposed on the same phase. A semiconductor device characterized by controlling timing. The semiconductor device according to claim 1, wherein:
A semiconductor device, wherein the semiconductor switch element, the drive circuit, the voltage detection circuit, and either or both of the phase detection circuit and the vibration detection circuit are stored in the same package.

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