JPS5881332A - Two-way switch circuit - Google Patents

Abstract

PURPOSE:To increase a switching frequency up to its limit, by providing an interlock so that series-connected transistors (TR) of a two-way switch circuit to prevent turn on at the same time. CONSTITUTION:If one switching circuit (e.g. 10) turns on, a TR (17) turns on by voltage drops across resistances (15 and 16) to make the output of the driving circuit (18') of the other switching circuit (10') ineffective, so both switching circuits never turn on at the same time. Therefore, the timing for switching is unnecessary in driving circuits 18 and 18', simplifying the constitution of the driving circuits.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bidirectional switch circuit used in an inverter circuit or the like using transistor switches.

2. Description of the Related Art Conventionally, a bidirectional switch circuit using transistor switches is one in which two transistor switches are connected in series between a DC power source, and the configuration shown in FIG. 1 is known. To explain its configuration based on the drawings, the DC power supply 1
Transistor switches 2 and 3 of opposite polarity are connected in series between them, and flywheel diodes 4 and 5 are connected in antiparallel to each transistor switch 2 and 3. The transistor switches 2 and 3 are driven by base drive circuits 6 and 7, respectively, and their drive waveforms are such that the upper and lower transistor switches 2.3 are turned on at the same time, as shown in FIG. The switching timings t, , and t2 are designed to prevent short-circuiting of the power supply.

The switching timing times t1 and t2 must be made larger than the sum of the switching storage time and the off-fall time of each transistor switch 2, 3 when the transistor switches 2 and 3 are turned off. However, if it is made larger than necessary, when used in pulse width modulation, the control range will be limited, especially when the switching frequency is high, and the storage time and off-fall time of the transistor itself will also be affected by variations in the transistor itself, collector It was a big problem which value to set since it changes depending on the current and junction temperature.

The present invention has been made in view of the above-mentioned problems, and the present invention allows transistors to be switched at the minimum switching timing time in the switching operation at that point, taking into account variations in the transistor itself, collector current, and dependence on junction temperature. This is intended to perform switching operations.

Hereinafter, embodiments of the present invention will be described with reference to FIG. In the figure, 10.10' indicates transistor switches 11', 11' and a first diode 12.1 connected in the forward direction.
The first and second switch circuits are configured by integrating second diodes 13 and 13 in antiparallel to a series circuit of 2'.
This switch circuit 10. ．． 10' is connected in series between the DC power supply 14 so that the transistor switches 11 and 11' are located on the power line side. 15.16 and 15',
16' denotes each transistor switch 11, . . . of the first and second switch circuits 10, 10'. The connection point between 11' and the first diode 12.12'! The first and second resistors are connected between L, IL' and the DC power supply 14, and the second resistor 15',
16' is a DC power supply 14 so that current flows when the transistor switch 11' of the second switch circuit 10' is turned on.
The first resistor 15.16 is connected between the positive power supply line of the DC power supply 1 and the connection point a' so that current flows when the transistor switch 11 of the first switch circuit 1o is turned on.
It is connected between the negative side power supply line of No. 4 and connection point a.

17.17' are the first and second resistors 15.16 and 16'
, 16', the transistors of the first and second switch circuits 10 and 10' supplied from the base drive circuit 18 and 18'. switch 1
1 and 11' are connected to switch the base drive currents.

In the above configuration, the first switch circuit 10 is configured by the transistor switch 11 and the diodes 12 and 13.
Transistor switch 11/and diode 12', 13
' constitutes the second switch circuit 10',
The transistor which is the second current switch means 17' operated by the current flowing through the second resistors 15' and 16' is the transistor switch 1 from the base drive circuit 1B.
Similarly, the first current switching means 17 operated by the current flowing through the first resistor 15 and 16 switches the base drive current to the transistor switch 11' from the drive circuit 1B'. The transistors 11' or 1 which are symmetrical while the current is flowing through the transistor switch 11 or 11' are interlocked with each other.
1, even if there is a signal from the base drive circuit 18 or 18', the base drive current is prevented from flowing, and at the same time it is prevented from being turned on.

As is clear from the above description, in the present invention, the current is switched by the first and second current switch means, and an interlock is taken so that the first and second switch circuits are not turned on at the same time. The effects of storage time and off-fall time when the switch is turned off can be minimized, and the switching frequency can be raised to its limit. Further, since there is no need to set the timing for switching in the drive circuit, the drive circuit can be simplified.

[Brief Description of the Drawings] Fig. 1 is a circuit diagram of a conventional bidirectional switch circuit, Fig. 2 is a pace drive waveform diagram in the same circuit, and Fig. 3 is a bidirectional switch circuit according to an embodiment of the present invention. It is a circuit diagram. 1o...first switch circuit, 10'...
...Second switch circuit, 11.11'...Transistor switch, 12.12'...First diode, 13°13'...Second diode , 14...DC power supply, 16.16...
- First resistor, 15', 16'... Second resistor, 17... First current switch means, 17'.
...Second current switch means, 18.18'...
...Base drive circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 1θ

Claims (1)

[Claims] The first switch circuit includes first and second switch circuits in which a second diode is connected in antiparallel to a series circuit of a transistor switch and a first diode connected in the forward direction, and a base drive circuit for the transistor switch, and a base drive circuit for the transistor switch. and a second switch circuit are connected in series between the DC power supplies such that the transistor switch is located on the power supply line side, and the connection point between each transistor of the first and second switch circuits and the first diode and the First and second current switch means, each of which is connected to a DC power source and has first and second resistors through which current flows when each transistor switch is on, and is operated by the current flowing through the resistors. The first and second
A bidirectional switch circuit in which the transistor switches in the switch circuit are connected to switch the base currents of each transistor switch.