JPS6288425A - Drive circuit for semiconductor device - Google Patents

Abstract

PURPOSE:To miniaturize the circuit and to improve the efficiency by inserting an inductance applied with a voltage changed over alternately in both polarities to a current drive circuit of a current drive type semiconductor device such as a GTO thyristor. CONSTITUTION:In closing a semiconductor switch 3, a current from an on-side DC power supply 1 is fed to a gate of the GTO thyristor 6, which is turned on and in this case, the current (i) in the inductance 9 is increased by the on-side DC power supply 1 when the semiconductor switch 3 is closed and decreased by a subtracting DC power supply 7 when the switch 8 is closed so as to control the mean value of the current (i). Further, the control of the mean value of the output current (i) is applied by comparing and operating an output signal I of a current detector 10 and a set current value I* by a comparison operating device 11 so as to control the on-width of the semiconductor switches 3, 8. Since a loss such as a current limiting resistor does no exists in the control, the high frequency and miniaturized circuit are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive circuit for a current-driven semiconductor device such as a thyristor GTO thyrisk (gate turn-off thyrisk) or a transistor.

[Conventional technology]

Taking GTO thyristor 6 as an example of such a semiconductor device, conventionally an on-side power supply circuit and an off-side power supply circuit are connected in parallel between the gate and cathode of the GTO thyristor 6, as shown in FIG. The power supply circuit has an on-side DC power supply 1, a resistor 5, and a semiconductor switch 3 connected in series to terminals, and an off-side power supply circuit has an off-side DC power supply 1 and a semiconductor switch 4 connected in series.

In this way, in the on-side power supply circuit, the semiconductor switch 3
When the gate is closed, the output current flowing from the power source 1 is limited by the resistor 5 and applied to the gate.

[Problem that the invention seeks to solve]

However, in the conventional circuit, since the resistor 5 is used to limit the on-side output current, this resistor 5 generates a loss.
Particularly in the case of a large-capacity GTO Cyrisk, the loss in this resistor 5 increases and the resistor itself becomes larger, which in turn has the disadvantage that this resistor 5 cannot fit inside the printed circuit board, making the entire circuit larger. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a drive circuit for a semiconductor device that can limit output current without using a resistor, thereby reducing loss and reducing the size of the circuit.

[Means for solving problems]

In order to achieve the above object, the present invention is characterized in that an inductance is interposed in a drive current output circuit for a current-driven semiconductor device, and means is provided for alternately switching the voltage applied to this inductance between positive and negative. It is.

[Effect]

According to the present invention, a drive output current to a semiconductor device is caused to flow through an inductance, and this output current is controlled by alternately making the voltage of this inductance positive and negative. As a result, the efficiency of the circuit can be improved and the size can be reduced.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of a driving circuit for a semiconductor device according to the present invention, and similar to FIG. 3 showing the conventional example, GT
This is the case of the drive circuit of OSIRISK6.

In the present invention, the inductance 9 is connected to the gate and cathode terminal of the GTO thyristor 6 in series with the on-side DC power supply 1 in the drive current output circuit, and the inductance 9 is connected to the gate and cathode terminal of the GTO thyristor 6 in series with the on-side DC power supply 1 and the semiconductor switch 3. A series circuit of a DC power source 7 for current reduction and a semiconductor switch 8 is connected in parallel with.

Further, a current detector 10 is provided between the inductance 9 and the gate of the GTO thyristor 6, and a comparison calculator If is connected to the output side of the current detector 10, and a logic inverter 12 is connected to the output side of the comparison calculator 11. A semiconductor switch 8 and directly a semiconductor switch 3 are connected.

Next, to explain the operation, when the semiconductor switch 3 is closed, the current from the on-side DC power supply 1 is transferred to the GTO thyristor 6.
In this case, when the semiconductor switch 3 is closed, the current i in the inductance 9 is increased by the on-side DC power supply l, and when the semiconductor switch 8 is closed, it is decreased by the current reduction DC power supply 7. By doing this, the average value of j can be controlled. However, semiconductor switches 3 and 8 must not be closed at the same time.

Further, in order to control the average value of the output current i, the output signal I of the current detector 10 and the set current value ■* are compared and calculated in a comparison calculation 11 to control the ON width of the semiconductor switches 3 and 8. However, the logic inverter 12 is used to turn the semiconductor switch 8 on and off in response to the on and off of the semiconductor switch 3.

FIG. 2 shows a second embodiment of the drive circuit of the present invention.
The difference from the first embodiment shown in FIG. 1 is that the off-side DC power supply 2 shown in FIG. When the semiconductor switch 13 is connected in parallel and the GTO thyristor 6 is turned off, not only the semiconductor switch 4 but also the semiconductor switch 13 is closed. A negative output current can be obtained.

In both the first and second embodiments, the inductance 9 is connected to the semiconductor switches 3 and 8. Alternatively, when the switch frequency of No. 4 is sufficiently high, only the wiring inductance is sufficient.

〔Effect of the invention〕

As described above, the semiconductor device drive circuit of the present invention has less loss due to resistance than the conventional drive circuit using a current reducing resistor, so efficiency is improved and the entire circuit is miniaturized. It is something.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a driving circuit for a semiconductor device according to the present invention, FIG. 2 is a circuit diagram showing a second embodiment of the same, and FIG. 3 is a circuit diagram showing a conventional example. 1...On side DC power supply 2...Off side DC power supply 3
...Semiconductor switch 4...Semiconductor switch 5.
...Resistance 6...GTO Zyristor 7.
...DC power supply for current reduction 8...Semiconductor switch 9...
・Inductance 10...Current detector 11...
Comparison calculator 12...Logic inverter 13...Semiconductor switch

Claims (1)

[Claims] 1. A drive circuit for a semiconductor device, characterized in that an inductance is interposed in a drive current output circuit for a current-driven semiconductor device, and means is provided for alternately switching the voltage applied to the inductance between positive and negative.