JPH02264517A - Driving circuit and driving device for thyristor - Google Patents

Abstract

PURPOSE:To isolate a thyristor and a driving circuit, to enable turning on/off even when a level at the terminal of the thyristor is unstable and to reduce the number of components by adopting the MOS structure for the ON/OFF gate. CONSTITUTION:A gate voltage is applied to a P-channel MOS gate 2 at turn-on or a gate voltage is applied to an N-channel MOS gate 3 to turn on a thyristor 1. That is, an inverting layer is generated in the n2 layer or the P3 layer of the thyristor 1, which is turned on by being injected with falls from a P1 layer or an anode A or with electrons from a cathode K. Moreover, at turn-off, a gate voltage is applied to the gate of the P-channel MOSFET 4 or the gate of an N-channel MOSFET 5, then the thyristor 1 is turned off via npn TRs 6, 7. Thus, the isolation between the input and output is attained and the thyristor 1 is driven regardless of the terminal potential level of the thyristor 1 and the number of components is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a turn-off circuit capable of floating drive and insulation between input and output when a thyristor is used as a semiconductor switch, and a drive circuit thereof.

[Conventional technology]

Thyristor family devices, which mainly have a pnpn structure, can relatively easily obtain high blocking voltages in the forward and reverse directions, and can turn on a large amount of power with a small on-drive power, and are widely used as switching elements. It's being used.

Although thyristors have a self-holding property in which current continues to flow even without applying a drive signal after turning on, on the other hand,
At turn-off, it is necessary to forcibly apply a reverse bias, and other external measures are required. As described in Japanese Patent Publication No. 60-40739, the conventional device has a gate terminal in the p base layer, and when turned off, the gate terminal is turned off by applying a reverse bias between the gate and the cathode. It is turned off by drawing current.

[Problem to be solved by the invention]

In the conventional example described above, no consideration was given to insulation between input and output, and there was a problem that minute signals could not be detected with high precision. In addition, at turn-off, the gate terminal and cathode terminal must be reverse biased at any potential, so a floating power supply is required, and since the thyristor is a unidirectional semiconductor switch, it cannot be used as a bidirectional switch. This resulted in problems such as requiring twice the number of elements including the drive circuit.

The object of the present invention is to provide insulation between the thyristor and the drive circuit;
Another object of the present invention is to provide a thyristor drive circuit that can turn on and turn off even if the potential at the terminal of the thyristor is unstable.

Another object of the invention is to turn on the thyristor.

The object of the present invention is to provide a device capable of driving a circuit that can be turned off.

Still another object of the present invention is to reduce the number of elements in a circuit that drives the thyristors when two unidirectional switch thyristors are used to create a bidirectional switch.

[Means to solve the problem]

In order to achieve the above objective, the base current of the transistor for shorting the pn junction during the turn-off operation of the thyristor is divided into a part of the anode current and the MO
By supplying via SFET, current flow between input and output is prevented and insulation is achieved between input and output, and MOS gates are formed so that the anode and cathode can be driven with reference to each for floating drive. be.

In addition, an n-channel M for turn-off and turn-on where a gate voltage is applied with reference to the semiconductor layer adjacent to the anode.
To drive the OS gate, you need a p-channel gate drive power supply, a diode, and a resistor.

A flip-flop circuit constituted by a MOSFET is configured to apply either the potential of the semiconductor layer adjacent to the anode or the p-channel gate drive power supply voltage, and the turn-off circuit is configured to apply the gate voltage with respect to the cathode.・In order to drive the turn-on n-channel MOS gate, an n-channel gate drive power supply,
The cathode potential or n
One of the channel gate drive power supply voltages is applied.

Furthermore, in order to reduce the number of elements in the drive circuit when making a bidirectional switch, two thyristors are connected in antiparallel, and an n-channel MOS gate for turn-off, an n-channel MOS gate for turn-off, and an n-channel M for turn-on are connected.
The OS gate and the turn-on n-channel MOS gate are connected to each other so that they can be driven by the same drive circuit.

[Effect]

By making the gate for turning on the thyristor a MOS gate structure, it becomes a voltage-driven type, which prevents current from flowing from the drive circuit and achieves insulation between input and output. When it is off, the base current of the transistor that shorts the pn junction and a part of the anode current are connected to other transistors and MOS.
Since the base current is supplied via a FET and switched by a voltage-driven MOSFET, insulation between input and output can be achieved even when off. In addition, by forming a p-channel gate that is controlled on and off based on the anode and an n-channel gate that is controlled on and off based on the cathode, switching can be performed even if the potential of the switch terminal is unstable from the drive circuit. becomes possible.

n-channel M for thyristor turn-on/turn-off
By applying complementary signals to the gates of the two n MOSFETs that constitute the flip-flop circuit for driving the OS gate, the n MOSFETs are turned on.
A P-channel gate drive power supply voltage (hereinafter referred to as Vss) is generated at the drain of the MOSFET, and this voltage is applied to the gate of the P-channel MOSFET, which is connected via a resistor from the drain of the n-MOSFET that is in the off state. For turn-on of the thyristor (
Vss is applied to the P channel gate (or for turn-off). Since the p MOSFET to which Vss of the flip-flop circuit is applied is in the on state, the potential of the semiconductor layer adjacent to the anode of the thyristor is generated at its drain, so the p MOSFET for turning off (or turning on) the thyristor is generated. The potential of the semiconductor layer adjacent to the anode is applied to the channel gate. In this way, MOSFE
In a flip-flop circuit made up of T, in a steady state, one of the two MOSFETs in series between the semiconductor switch and the drive power supply is off, so no current flows between the input and output. Insulation between input and output is possible. Similarly, by using a flip-flop circuit to drive the n-channel MOS gate for turn-on and turn-off of the thyristor, two MOSFETs are connected in series between the semiconductor switch and the drive power supply in a steady state.
Since one of the two is in the off state, no current flows between the input and output, so insulation between the input and output is possible.

The semiconductor layer adjacent to the anodes of two thyristors connected in parallel is always approximately equal to the higher potential side of the switch terminal, regardless of forward or reverse bias, so it is possible to connect, and the potential of this semiconductor layer MOS gates to which gate voltages are applied based on can be driven by the same drive circuit.

In other words, the n-channel MOS gates for turn-on and the p-channel MOS gates for turn-off are connected together and can be driven by the same circuit. In addition, in the case of an n-channel gate where the gate voltage is applied with the cathode as a reference, by using the low potential side of the switch terminal as a reference, the turn-on n channels and the turn-off n channels are connected and driven in the same way. Can be driven by a circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, (a) shows a block diagram of the main switch having a pnpn structure, its turn-off circuit, and a drive circuit, and (b) shows the state of voltage application to the p-channel gate in the off state.

(c) shows the voltage application state of the n-channel gate in the off state, (d) shows the voltage application state of the p-channel gate in the on state, and (e) shows the voltage application state of the n-channel gate in the on state. show. 1 is pln as the main switch! p3
A thyristor with an n4 structure, 2 is an n for turn-on that applies a gate voltage based on the potential of the 02 layer in the middle of the thyristor.
Channel MOS gate; 3 is a turn-on n-channel MOS gate to which a gate voltage is applied based on the cathode K; 4 is a turn-off p-channel MO5FET to which a gate voltage is applied based on the potential of the 02 layer; 5 is a cathode K A turn-off n-channel MOSFET that applies a gate voltage to the reference, 6 a pnp transistor, 7 an npn transistor for shorting the pn junction on the cathode side,
8 is a resistor, S is a p-channel gate drive circuit, and S2 is n
This is a channel gate drive circuit. At turn-on, by applying a gate voltage to the p-channel gate 2, an inversion layer is created in the n2 layer, and holes are injected from the 91 layer that contacts the anode A, and electrons are injected from the n4 layer that contacts the cathode K, or the cathode By applying a gate voltage from K to the n-channel gate 3, an inversion layer is generated in the 23rd layer, and electrons are injected from the cathode K and holes are injected from the anode A, so that the thyristor 1 is turned on.

P channel MOSFE from anode A at turn-off
By applying a gate voltage to the gate of T 4 or by applying a gate voltage from the cathode K to the gate of the n-channel MOSFET 5, the thyristor 1 in the on state has a current flowing from the anode A to the cathode K, and the anode A
A base current corresponding to the current flowing through the thyristor flows through the pnp transistor 6 whose base is connected to the emitter nz layer. Therefore MOSFET 4, or MOSFET
When any of ET 5 turns on, the pnpt' range starts from anode A.

n-channel MOSFET 5 or p-channel MO5FE
Current flows to the base of the npn transistor 7 through T4, and the npnh transistor turns on, shorting the pn junction p3-94 on the cathode side of the thyristor 1 and reducing electron injection from the n4 layer on the cathode side. Turn off by letting. According to this embodiment, even if the potential of the thyristor 1 is unstable, it is possible to turn it on and off, that is, floating drive is possible. or,
Since it can be controlled by voltage by using MOS gate drive, M! between input and output can be controlled by voltage. There is a fringe effect.

Another embodiment of the present invention will be described with reference to FIG.

9.14 is an n-channel MOS for p-channel gate drive
FET, 10.13 is a resistor, 11.12 is a p-channel MOSFET for p-channel gate drive, 15゛ is a diode for n-channel gate drive, 19.24 is a p-channel MOSFET for n-channel gate drive, 20゜23 is a resistor , 21.22 is n MOSF for n channel gate drive
ET, 18 is an n-channel gate driving diode, 16
2.17 is p that constitutes an inverter.

n MOSFET. To turn on the thyristor when the potential of the thyristor is low, apply a LOW signal, that is, the voltage of Vss, to IN, and the p MO5FET
24 is turned on, the p MOSFET 19 is turned off by the signal inverted by 16 and 17 forming the inverter, vDD is applied to the gate of the n MOSFET 21 and turned on, and the potential of the cathode of the n MOSFET 22 is applied to the gate and turned off. Therefore, the main switch thyristor 1. A voltage of vDD is applied to the on-use n-channel gate 3 of the thyristor, and the thyristor is turned on. Conversely, when the potential of the thyristor is high and the thyristor is turned on, I
n channel MO5FET 14 by LOW signal to N
is off, n is turned off by the signal inverted by the inverter
MOSFET 9 is on, Vss is applied to the gate of p MOSFET 12 and on, p MOSFET
The potential of layer 02 of thyristor 1 is applied to the gate of thyristor 11 to turn it off, and Vss is applied to the turn-on p-channel gate 3 of thyristor 1, so that thyristor 1 is turned on. When turning off thyristor 1, IN is set to HIGHT.
By applying the signal vDD, the states of the n-channel gate drive circuit and the p-channel gate drive circuit are inverted. Therefore, the potential of the cathode is applied to the n-channel gate 3 of the thyristor 1, and the potential of n2 is applied to the p-channel gate 2 of the thyristor 1. A layer potential is applied and no channel is created to turn on. When the potential of the thyristor is low, Voo is applied to the gate of the turn-off n MOSFET 5, so part of the current at the anode A flows through the n MOSFET 5 via the pnp transistor 6, and the pn junction is shorted. The npn transistor 7 is turned on because the base current of the npn )-rangestaff is supplied, and the pδ-n4 junction of the thyristor 1 is short-circuited to reduce electron injection from the n4 layer, thereby turning the thyristor 1 off. When the potential of the thyristor 1 is high, Vss is applied to the gate of the turn-off p MOSFET 4, so a part of the anode current flowing through the on-state thyristor 1 is transferred to the p MOSFET via the pnp transistor 6.
The current flows through SFET 4 and supplies the base current of npn transistor 7, which turns on npn transistor 7, shorts the p3-n4 junction, reduces electron injection from the n4 layer, and turns thyristor 1 off. According to the embodiment, since one of the two MOSFETs connected in series in the Ppn channel drive circuit is in the off state, no current flows between the power supply and the thyristor, so there is no input/output. insulation between them is maintained.

Still another embodiment of the present invention will be described with reference to FIG. 1
' is a thyristor connected in antiparallel to thyristor 1, and 2
' is a p-channel MOS gate for turning on thyristor 1';
3' is an n-channel MOS gate for turning on the thyristor 1', and 4' is a p-channel MOSFE for turning off the thyristor 1'.
T, 5' is an n-channel MOSF for turning off thyristor 1'
ET, 6' is a pnpl-transistor, 7' is an npn transistor for shorting the pn junction of thyristor 1', 8' is a resistor, and 25.26 is an n MOSFET that detects the lower potential of the switch terminal Tl or T2. be. The gate of p-channel MO5FET 4.4' for turn-off, the gate of n-channel MO5FET 5.5', the p-channel gate 2, 2' and n-channel gate 3, 3' for turn-on, and the gate of thyristor 1, 1'. The 02 layer is short-circuited to provide a reference potential for the p-channel gate drive circuit,
A low potential at either the cathode of thyristor 1 or 1' is detected and provided as a reference potential for the n-channel gate drive circuit. According to this embodiment, by using a common gate for each turn-on and turn-off, the same drive circuit is required, so a bidirectional switch can be obtained without doubling the number of constituent elements.

〔Effect of the invention〕

According to the present invention, since the ON and OFF gates have an MO8 structure, no current flows between the input and output, and insulation can be achieved between the input and output.

Further, by driving the thyristor with a MOS gate that applies a gate signal with reference to the semiconductor layer adjacent to the anode and the cathode, there is an effect that the thyristor can be driven regardless of whether the potential of the thyristor is high or low.

Also, a p-channel gate for turning on the thyristor connected in antiparallel, an n-channel gate for turning it on, a p-channel gate for turning it off,
By connecting the n-channel gates, the drive circuits can be made the same, which has the effect of reducing the number of constituent elements and chip size when integrated.

[Brief explanation of drawings]

FIG. 1 is a driving circuit diagram of a thyristor according to an embodiment of the present invention;
2 is a circuit diagram showing a driving device including a gate driving circuit as another embodiment of the present invention, and FIG. 3 is a circuit diagram showing still another embodiment of the present invention. be. 1.1'...Sirisk switch, 2,2'...P-channel MOS gate for on, 3,3'...n for on
Channel MOS gate, 4,4'... p-channel MO9FET for off, 5.5'... n-channel M for off
OSFET, 6.6'... pnp transistor, 7.
7'-npn transistor, 8,8' 10,1
3,20°23...Resistance, 9,14,16,21,2
2,25°26-n channel MOSFET, 11,1
2.17°19.24...p channel MOSFET,
15.18...Diode, A...Anode, K.
...Cathode, Tl. T2...Switch terminal, Vss...P channel gate drive power supply, vDD...N channel gate drive power supply,
IN...Control signal input. (b) (,C) Figure 1 (cL) (,cL) (e)

Claims (1)

[Claims] 1. A MOS gate thyristor as a main switch that is turned on by applying a gate voltage with respect to the anode or cathode, the emitter of the first transistor at the cathode, and a semiconductor layer adjacent to the cathode. The collector is connected to the base, and the drain of the p-channel MOSFET and the source of the n-channel MOSFET are connected to the base.
Source of channel HOSFET and n-channel MOSFE
Driving a thyristor, characterized in that the drain of the T is connected to the collector of a second transistor, the base of the second transistor is connected to a semiconductor layer adjacent to the anode layer of the thyristor, and the emitter is connected to the anode of the thyristor. circuit. 2. The p-channel gate drive circuit for turning on and turning off the thyristor uses two n-channel MOSFETs.
The sources of the two n-channel MOSFETs are connected in common, and the anode of the diode is connected to the anode of the diode, and the cathode of the diode is connected to the p-channel gate driving power supply. A relative on/off signal is applied to the gate of each n-channel MOSFET, the drain of each n-channel MOSFET is connected to the drain of a p-channel MOSFET via a resistor, and the sources of the two p-channel FETs are connected to the thyristor. Connected to the semiconductor layer adjacent to the anode, two p-channel MOS
The gates of the FETs are connected to the drains of nMOSFETs whose respective drains are not connected via resistors, and the p-channel MOS gate for turning on the thyristor is connected to the drain of one of the p-channel MOSFETs, and the p-channel MOSFET for turning off the thyristor is connected to the drain of one of the p-channel MOSFETs. The gate of the other p
In addition to being connected to the drain of the channel FET, the n-channel gate drive circuit for turn-off and turn-off of the thyristor commonly connects the sources of the two p-channel MOSFETs, and is further connected to the cathode of the diode.
The anode of the diode is connected to the n-channel gate drive power supply, and a switch on/off signal is applied to one of the gates of the two p-channel MOSFETs, and a relative signal of the on/off signal is applied to the other gate. The drain of each p-channel MOSFET is connected to the drain of an n-channel MOSFET via a resistor, the sources of the two n-channel FETs are connected to the cathode of a thyristor, and two
The gates of the n-channel MOSFETs are connected to the p-channel MOSFETs whose drains are not connected through a resistor.
The n-channel MOS gate for turning on the thyristor is connected to the drain of one of the n-channel M
An n-channel M for turn-off is connected to the drain of the OSFET.
A thyristor drive circuit characterized in that the gate of an OSFET is connected to the drain of the other n-channel MOSFET. 3. The semiconductor switch consists of two thyristors connected in antiparallel, and two p-channel MOs for turn-off as described in item 1.
S gates and two n-channel MOS gates are commonly connected, two turn-on p-channel gates and two n-channel gates are also commonly connected,
The semiconductor layers adjacent to the anodes of the thyristors are also connected to each other, and the sources of the two commonly connected p-channel gates constituting the p-channel gate drive circuit of the thyristor described in Section 2 are connected to the semiconductor layers adjacent to the anodes of the thyristors. Then, both terminals of the semiconductor switch are newly connected to the drains of each of the two n-channel MOSFETs, and the gates of the two n-channel MOSFETs are connected to the terminal of the other semiconductor switch to which each drain is not connected. The sources of the two n-channel MOSFETs connected to each other are common, and the commonly connected sources and the two n-channel MOSFETs constituting the n-channel gate drive circuit of the thyristor described in section 2.
A thyristor driving device characterized in that commonly connected sources of channel MOSFETs are connected to each other.