JPH10209832A - Semiconductor switch circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a rate of change of voltage (dv/dt) of the semiconductor switch circuit that is used for a switching means of a power converter. SOLUTION: An IGBT 30 as a self-extinction of arc device is used for a main switch element, a MOSFET 31 as an auxiliary switch element is connected in parallel with the IGBT 30, a built-in diode of the MOSFET 31 is used for a flywheel diode, a resistor 31 is connected between a gate terminal and a source terminal of the MOSFET 31, and the dv/dt to be produced is reduced by utilizing the operation of the MOSFET 31 when the IGBT 30 is turned off or when the current flowing to the built-in diode is recovered reversely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor switch circuit used as a switching means of a power converter such as an inverter.

[0002]

2. Description of the Related Art FIG. 8 is a main circuit configuration diagram of a typical single-phase inverter as a power converter of this type. 8, reference numeral 1 denotes a DC power supply, 2 denotes an inverter main circuit, 3 denotes a load, and the inverter main circuit 2 includes a snubber capacitor 10 and semiconductor switch circuits 11 to 14. Each of the semiconductor switch circuits 11 to 14 is a bridge. Connected to the configuration. These semiconductor switch circuits generally have the same circuit configuration, and the respective semiconductor switch circuits are individually turned on and off in cooperation with each other, so that the voltage of the DC power supply 1 is converted into a desired AC voltage. The load 3 is supplied.

FIG. 9 is a detailed circuit configuration diagram showing a conventional example of each of the semiconductor switch circuits 11 to 14 shown in FIG. In FIG. 9, reference numeral 20 denotes an insulated gate-bipolar transistor (hereinafter simply referred to as IGB) as a self-extinguishing device.
T), 21 is a free wheel diode connected in anti-parallel to the IGBT 20, and 22 is connected between an output terminal of a drive signal circuit (not shown) for generating a drive signal for turning on and off the IGBT 20 and a gate terminal of the IGBT 20. This is the gate resistance.

The operation of the semiconductor switch circuit when the IGBT 20 is turned off will be described below with reference to a waveform diagram at the time of turn-off shown in FIG. 10, when the drive signal at time T ₁ is an instruction to turn off IGBT 20, IGBT 20 starts turn-off operation, I
GBT20 collector-emitter voltage (V _CE) is increased as shown (see FIG. 10 (b)), at time T _2, and V _CE reaches the DC power supply 1 voltage (E) (FIG. 10 (b) see), it to the collector current flowing through the IGBT 20 (I _C) is decreased as shown (FIG. 10 (b) refer), I _C becomes zero at time T ₃ reference (FIG. 10 (b)), the turn-off The operation is completed.

[0005] V _CE at the time of turning off the IGBT 20 described above
The voltage rise rate and turn-off loss (the hatched portion in FIG. 10B) depend on the resistance value of the gate resistor 22. When the resistance value is increased, the voltage rise rate of V _CE becomes smaller. Also, the turn-off loss has a larger value. When the load 3 of the power converter is an inductive load, for example, there is a period in which the current of the load 3 flows through the freewheel diode 21 of the semiconductor switch circuit 11 shown in FIG. When the IGBT of the semiconductor switch circuit 12 is commanded to turn on, the IGBT starts to turn on, the current of the freewheel diode 21 of the semiconductor switch circuit 11 decreases to zero, and the freewheel diode 21 performs a reverse recovery operation. , Semiconductor switch circuit 1
The IGBT No. 2 completes the turn-on operation, but the voltage increase rate during the reverse recovery operation also depends on the resistance value of the gate resistance of the semiconductor switch circuit 12, and when the resistance value is increased, the voltage increase rate becomes smaller. And the turn-on loss of the IGBT of the semiconductor switch circuit 12 becomes a larger value.

The snubber capacitor 10 shown in FIG.
FIG. 1 shows a surge voltage generated when each of the semiconductor switch circuits 11 to 14 performs the above-described switching operation.
The surge voltage of V _CE during the period from time T ₁ to time T ₃ shown in FIG. 0 is suppressed to prevent each IGBT constituting the semiconductor switch circuit from being damaged by overvoltage.

[0007]

The switching operation of a semiconductor switch circuit constituting a power conversion device such as the above-described single-phase inverter is generally pulse width modulated (PWM) with a carrier frequency of about several KHz to about several tens KHz. The switching operation generates switching noise of a frequency component of several tens KHz or more from the power conversion device.

[0008] In recent years, among the frequency components of the switching noise, various legal regulations have been imposed on the power conversion device in order to suppress the adverse effect on the external equipment by the component of 100 KHz or more. In addition, there is a demand for a reduction in the rate of increase in the voltage of the semiconductor switch circuit which is a source of the switching noise. However, in the conventional semiconductor switch circuit, when the resistance value of the gate resistance connected to the gate terminal of each IGBT is increased to satisfy the above-described requirement of the reduction in the rate of voltage rise, the turn-off loss and turn-on of the IGBT are reduced. Since the loss increases together with the loss and the loss increases in proportion to the carrier frequency, the conversion efficiency of the power conversion device is reduced, and the cooling components of the IGBT become large. As a result, the power conversion device There was a problem of being larger.

An object of the present invention is to solve the above-mentioned problems and to provide a semiconductor switch circuit capable of suppressing a voltage increase rate during a switching operation of a power conversion device.

[0010]

According to a first aspect of the present invention, in a semiconductor switch circuit used as a switching means of a power converter, the semiconductor switch circuit uses a self-extinguishing device as a main switch element, and the main switch element is used as a main switch element. A MOSFET connected in parallel is used as an auxiliary switch element,
It is assumed that a resistor or a constant voltage diode is connected between the gate terminal and the source terminal of the MOSFET.

According to a second aspect of the present invention, there is provided a semiconductor switch circuit used as a switching means of a power conversion device, wherein the semiconductor switch circuit has a self-extinguishing device as a main switch element and an M switch connected in parallel to the main switch element.
An OSFET is used as an auxiliary switch element, and a resistor is connected between the gate terminal and the source terminal of the MOSFET.
It is assumed that a capacitor is connected between the gate terminal and the drain terminal of the ET.

According to a third aspect of the present invention, there is provided a semiconductor switch circuit used as a switching means of a power converter, wherein the semiconductor switch circuit has a self-extinguishing device as a main switch element and an M switch connected in parallel to the main switch element.
An OSFET is used as an auxiliary switch element, a first resistor is connected between the gate terminal and the source terminal of the MOSFET,
A resistor in which a P-channel device and a second resistor are connected in series at both ends of the resistor, connected in parallel, and a third resistor connected between a control electrode of the P-channel device and a control electrode of the self-extinguishing device; I do.

According to a fourth aspect of the present invention, there is provided a semiconductor switch circuit used as switching means of a power converter, wherein the semiconductor switch circuit has a self-extinguishing device as a main switch element and a MOSFET connected in parallel to the main switch element. An auxiliary switch element, a capacitor and a resistor connected in series between a gate terminal and a source terminal of the MOSFET are connected in parallel, and a diode is provided between the gate terminal of the MOSFET and a control electrode of the self-extinguishing device. Assume that they are connected.

According to the present invention, in the semiconductor switch circuit, a MOSFET as an auxiliary switch element is connected in parallel with a main switch element formed by a self-extinguishing device, and a built-in diode of the MOSFET is used as a freewheeling diode. By using a circuit configuration in which some electric components are added to the gate terminal, it is possible to suppress the rate of voltage increase during switching operation of the power conversion device as described later.

[0015]

FIG. 1 is a circuit diagram of a semiconductor switch circuit according to a first embodiment of the present invention. The semiconductor switch circuit 1 of the main circuit of the single-phase inverter shown in FIG.
1 to 14 respectively. In FIG. 1, reference numeral 30 denotes an IGBT as a main switch element, 31 denotes a MOSFET as an auxiliary switch element.
The SFET 31 has a built-in diode (diode indicated by a broken line in the drawing) which is equivalently formed between the drain and the source, 32 denotes a resistance between the gate terminal and the source terminal of the MOSFET 31, and 33 turns the IGBT 30 on and off. A gate resistor is connected between an output terminal of a drive signal circuit (not shown) that generates a drive signal and a gate terminal of the IGBT 30.

The operation of the semiconductor switch circuit when the IGBT 30 is turned off will be described below with reference to the waveform diagram at the time of turn-off shown in FIG. In FIG. 2, first, at time T ₁ , when the drive signal instructs the IGBT 30 to turn off, the IGBT 30 starts a turn-off operation,
The collector-emitter voltage (V _CE ) of the GBT 30 rises as shown (see FIG. 2A), and from time T ₁ to time T
_As the collector-emitter current (I _C ) of the IGBT 30 decreases to 2 as shown in the figure, the main current I ₀ of this semiconductor switch circuit becomes the path between the drain-gate capacitance (C _R ) of the MOSFET 31 and the resistor 32. to start the commutation, current I _C becomes zero at time T ₂ IGBT 30,
The turn-off operation of the IGBT 30 ends.

[0017] By flowing current I _R in the resistor 32 at this time, the voltage V _R occurs across the resistor 32 as shown in FIG. 2 (c), the voltage V _R is the MOSFET31 as the gate-source voltage Applied, MOSFET 31
There enters the active region, as a result, MOSFET 31 of the drain current (I _D) is the main current _{I 0 (= I C + I} D + I
_R ) starts to flow by sharing a part thereof, and this main current I ₀ has a substantially constant value until time T ₃ .

Therefore, the voltage V applied to the IGBT 30
_CEThe voltage rise rate (dV / dt) of the current I_RAnd said
Capacity (C_R) And the gate-source voltage of MOSFET 31
Pressure threshold (V_TH) DV / dt = I_R/ C
_R= V_TH/ (C_R・ Reduced to the value represented by resistor 32)
You. Next, at time T_ThreeAnd the voltage V of the IGBT 30_CEIs shown in FIG.
When the voltage (E) of the DC power supply 1 shown in FIG.
Quantity (C_R) Is completed and the current flowing through the resistor 32
(I_R) Is the discharge current from the gate of MOSFET 31
Switch. Therefore, the voltage V_RGradually decreases, and
Accordingly, the drain current (I _D) Also reduced
Less.

[0019] Next, at time T _4, gate-to-source voltage of MOSFET31 becomes less than or equal to the threshold value, MOSFET
The drain current ( _ID ) of the switch 31 becomes zero, and the off operation of the semiconductor switch circuit ends. 2, the collector current IGBT30 is at the turn-off from time T ₁ to time T ₂ (I _C), the collector-emitter voltage (V
_CE (see FIG. 2A)) is almost zero, and FIG.
The turn-off loss of the IGBT 30 (FIG. 2B) is suppressed by suppressing the aforementioned dV / dt.
(A hatched portion) has a small value.

FIG. 3 shows the case where the current (I _F ) becomes zero by performing a reverse recovery operation from the state where the current (I _F ) flows through the built-in diode of the MOSFET 31 of the semiconductor switch circuit shown in FIG. 3 is an operation waveform diagram of FIG. In FIG. 3, for example, the IG of the semiconductor switch circuit 12 shown in FIG.
An ON command is issued to the BT, and the IGBT starts to turn on. As shown in FIG. 3A, the current (I _F ) of the built-in diode of the MOSFET 31 of the semiconductor switch circuit 11 decreases, passes through zero, and moves in the reverse direction. becomes current, the reverse current from time T ₁ (I _F) decreases towards zero, so-called, the reverse recovery operation.

At this time, from the time T ₁ , the collector-emitter voltage (V _CE ) of the IGBT 30, that is, the MOSFET 31
The drain-source voltage rises from substantially zero as shown in FIG. 3 (b), this voltage V _CE MOSFET 31
A charging current flows through the path between the drain-gate capacitance (C _R ) and the resistor 32, and this charging current generates a voltage V _R across the resistor 32 as shown in FIG. _R is the gate-source voltage as MOSFET 31
Is applied to, MOSFET 31 enters the active region, the drain current (I _D) starts to flow in MOSFET 31, the current I _D is substantially constant value until the time T _2.

Therefore, the voltage V applied to the IGBT 30
_CEThe voltage rise rate (dV / dt) of the current I_RAnd said
Capacity (C_R) And the gate-source voltage of MOSFET 31
Pressure threshold (V_TH) DV / dt = I_R/ C
_R= V_TH/ (C_R・ Reduced to the value represented by resistor 32)
You. Next, at time T_TwoAnd the voltage V of the IGBT 30_CEIs shown in FIG.
When the voltage (E) of the DC power supply 1 shown in FIG.
Quantity (C_R) Is completed and the current flowing through the resistor 32
(I_R) Is the discharge current from the gate of MOSFET 31
Switch. Therefore, the voltage V_RGradually decreases, and
Accordingly, the drain current (I _D) Also reduced
A little, time T_ThreeTo zero, and the built-in
The operation based on the reverse recovery current of the ion is ended.

FIG. 4 is a circuit diagram of a semiconductor switch circuit according to a second embodiment of the present invention. The semiconductor switch circuits 11 to 14 of the main circuit of the single-phase inverter shown in FIG.
It corresponds to each. In FIG. 4, reference numeral 40 denotes an IGBT as a main switch element; 41, a MOSFET as an auxiliary switch element;
1 has a built-in diode (a broken-line diode shown in the figure) between the drain and the source.
A constant voltage diode between the gate terminal and the source terminal of 1;
Reference numeral 3 denotes a gate resistor connected between an output terminal of a drive signal circuit (not shown) for generating a drive signal for turning on / off the IGBT 40 and a gate terminal of the IGBT 40.

This semiconductor switch circuit has a constant voltage diode 42 in place of the resistor 32 in the circuit of the first embodiment of the present invention shown in FIG.
The operations at the time of turning off the T40 and at the time of reverse recovery of the built-in diode of the MOSFET 41 are almost the same as those of the first embodiment shown in FIGS. It becomes easy to limit the inter-voltage to the allowable value or less.

FIG. 5 is a circuit diagram showing a semiconductor switch circuit according to a third embodiment of the present invention. The semiconductor switch circuits 11 to 14 of the main circuit of the single-phase inverter shown in FIG.
It corresponds to each. In FIG. 5, reference numeral 50 denotes an IGBT as a main switch element; 51, a MOSFET as an auxiliary switch element;
1 has a built-in diode (diode indicated by a broken line in the figure) between the drain and the source.
1, a resistance between the gate terminal and the source terminal;
ET51 is a capacitor between the drain terminal and the gate terminal,
An output terminal 54 of a drive signal circuit (not shown) for generating a drive signal for turning on / off the IGBT 50 and the IGBT 50
Is a gate resistor connected between the gate terminal and the gate terminal.

This semiconductor switch circuit is different from the circuit of the first embodiment of the present invention shown in FIG. 1 in that a capacitor 53 is provided between the drain terminal and the gate terminal of the MOSFET.
The operation at the time of reverse recovery of the built-in diode of the SFET 51 is substantially the same as that of the first embodiment shown in FIGS. 2 and 3. The capacitor 53 causes the voltage V _CE of the voltage V _CE applied to the IGBT 50 to rise. (DV / dt) can be easily adjusted.

FIG. 6 is a circuit diagram showing a semiconductor switch circuit according to a fourth embodiment of the present invention. The semiconductor switch circuits 11 to 14 of the main circuit of the single-phase inverter shown in FIG.
It corresponds to each. In FIG. 6, reference numeral 60 denotes an IGBT as a main switch element; 61, a MOSFET as an auxiliary switch element;
1 has a built-in diode (diode shown by a broken line in the figure) between the drain and the source.
1, a resistance between the gate terminal and the source terminal, 63 is a MOSFET as a P-channel device, 64 and 65 are resistors,
Reference numeral 66 denotes an output terminal of a drive signal circuit (not shown) for generating a drive signal for turning on / off the IGBT 60 and the IGBT 60
Is a gate resistor connected between the gate terminal and the gate terminal.

This semiconductor switch circuit includes a resistor 62 similar to that of the first embodiment of the present invention shown in FIG.
An additional circuit comprising a MOSFET 63, a resistor 64, and a resistor 65 is provided at both ends of the resistor 62.
The operations at the time of turning off the BT 60 and at the time of reverse recovery of the built-in diode of the MOSFET 61 are almost the same as those of the above-described first embodiment shown in FIGS. 2 and 3. With this additional circuit, the IGBT 60 is turned off and the IGBT 60 is turned off. The gate-emitter voltage is
When it is less than between the source, MOSFET 63 becomes large decreasing gradient of the gate-source voltage of the MOSFET 61 by turning on, the drain current of the MOSFET 61 (I _D) of the reduced time (time T ₃ in FIG. 2 -T ₄ ) can be reduced.

FIG. 7 is a circuit diagram of a semiconductor switch circuit according to a fifth embodiment of the present invention. The semiconductor switch circuits 11 to 14 of the main circuit of the single-phase inverter shown in FIG.
It corresponds to each. In FIG. 7, reference numeral 70 denotes an IGBT as a main switch element; 71, a MOSFET as an auxiliary switch element;
1 has a built-in diode (diode shown by a broken line in the figure) between the drain and the source.
3 is a resistor, 74 is a diode, and 75 is a gate resistor connected between the output terminal of a drive signal circuit (not shown) for generating a drive signal for turning on and off the IGBT 70 and the gate terminal of the IGBT 70.

IGBT in this semiconductor switch circuit
The operations at the time of turn-off of 70 and at the time of reverse recovery of the built-in diode of the MOSFET 71 are almost the same as those of the first embodiment shown in FIGS. 2 and 3. When an ON command is issued, the MOSFET 71 can be prevented from turning on. When an OFF command is issued to the IGBT 70, the reverse bias voltage based on the drive signal in the path of the resistor 73 → the capacitor 72 → the diode 74 → the resistor 75 is applied to the MOSFET 7.
Since it is applied between the gate and the source of one, MOSFET
The decrease time of the drain current (I _D ) at time 71 (time T in FIG. 2)
₃ reference between -T ₄₎ can be further reduced.

When the semiconductor switch circuit of each of the above-described embodiments is used for the main circuit of the single-phase inverter shown in FIG.
Or the snubber capacitor 10 can be omitted.

[0032]

According to the present invention, in a semiconductor switch circuit used as a switching means of a power conversion device, a bipolar transistor and a gate turn-off (G
TO) A MOSFET as an auxiliary switch element is connected in parallel with a main switch element formed by a self-extinguishing device such as a thyristor, a voltage-driven thyristor, or an IGBT.
By adopting a circuit configuration in which some electric components are added to the gate terminal of the MOSFET, it is possible to suppress the rate of voltage increase during the switching operation of the power conversion device as described above. This can prevent adverse effects on external devices.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a semiconductor switch circuit showing a first embodiment of the present invention.

FIG. 2 is a waveform chart illustrating the operation of FIG.

FIG. 3 is a waveform chart for explaining the operation of FIG. 1;

FIG. 4 is a circuit diagram showing a semiconductor switch circuit according to a second embodiment of the present invention;

FIG. 5 is a circuit diagram showing a semiconductor switch circuit according to a third embodiment of the present invention.

FIG. 6 is a circuit configuration diagram of a semiconductor switch circuit showing a fourth embodiment of the present invention.

FIG. 7 is a circuit configuration diagram of a semiconductor switch circuit showing a fifth embodiment of the present invention.

FIG. 8 is a main circuit configuration diagram of a typical single-phase inverter as a power converter.

FIG. 9 is a circuit configuration diagram of a semiconductor switch circuit showing a conventional example.

FIG. 10 is a waveform chart for explaining the operation of FIG. 9;

[Explanation of symbols]

1 DC power supply 2 inverter main circuit 3 load 10
... Snubber capacitors, 11 to 14 ... Semiconductor switch circuits, 20, 30, 40, 50, 60, 70 ... IGBTs,
21 ... reflux diode, 22, 33, 43, 54, 6
6, 75 ... gate resistance, 31, 41, 51, 61, 71
... MOSFET, 32, 52, 62, 64, 65, 73
... Resistance, 42 ... Constant voltage diode, 53, 72 ... Capacitor, 64 ... MOSFET, 74 ... Diode.

Claims (4)

[Claims] 1. A semiconductor switch circuit used as switching means of a power converter, wherein the semiconductor switch circuit has a self-extinguishing device as a main switch element, and a MOSFET connected in parallel with the main switch element as an auxiliary switch element; A semiconductor switch circuit comprising a resistor or a constant voltage diode connected between a gate terminal and a source terminal of a MOSFET. 2. A semiconductor switch circuit used as switching means of a power converter, wherein the semiconductor switch circuit has a self-extinguishing device as a main switch element, and a MOSFET connected in parallel with the main switch element as an auxiliary switch element; A semiconductor switch circuit comprising: a resistor connected between a gate terminal and a source terminal of a MOSFET; and a capacitor connected between a gate terminal and a drain terminal of the MOSFET. 3. A semiconductor switch circuit used as a switching means of a power converter, wherein the semiconductor switch circuit uses a self-extinguishing device as a main switch element, and a MOSFET connected in parallel with the main switch element as an auxiliary switch element. A first resistor is connected between the gate terminal and the source terminal of the MOSFET, and a P-channel device and a second resistor connected in series at both ends of the first resistor are connected in parallel. A semiconductor switch circuit comprising a third resistor connected between the control electrode of the self-extinguishing device and a control electrode. 4. A semiconductor switch circuit used as switching means of a power converter, wherein the semiconductor switch circuit has a self-extinguishing device as a main switch element, and a MOSFET connected in parallel with the main switch element as an auxiliary switch element; A capacitor and a resistor connected in series between a gate terminal and a source terminal of a MOSFET are connected in parallel, and a diode is connected between a gate terminal of the MOSFET and a control electrode of the self-extinguishing device. Semiconductor switch circuit.