JPH04190675A - Protecting device for power semiconductor - Google Patents

Abstract

PURPOSE:To prevent the destruction of an element caused by an imperfect gate pulse by providing a function which monitors the pulse width and voltage of a gate signal given to the element. CONSTITUTION:When a gate pulse is supplied to a GTO, a comparator 8 compares the voltage of the gate pulse and, when the voltage is higher than the lowest igniting voltage of the GTO, the output of the comparator 8 is inverted. A one-shot multivibrator 10 is connected to the output of the comparator 8 and generates a pulse of a prescribed time width on the basis of the output of the comparator 8. The pulse width is set to the minimum time required for igniting the GTO. Then the drive circuit of the next stage amplifies the pulse to a voltage required for igniting the GTO and gives the amplified pulse to the gate of the GTO to turn on the GTO.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a protection system for elements such as VVVF inverters using GTO and the like.

[Conventional technology]

Proceedings of the 21st Domestic Symposium on the Use of Cybernetics in Railways (1) High-frequency 4-quadrant chopper (2) The control methods for main circuit elements listed in the development of 670 KVA auxiliary inverter for 3000 V DC electric locomotives are all gate pulses. A gate amplifier is provided at the subsequent stage of the creation (generation) circuit, and this amplifies the power necessary for ignition of the element, which is then applied to the gate of the element as a gate pulse.

In this type of system, there is no protection in the event that an incomplete gate pulse is generated due to a malfunction or malfunction after the gate amplifier, and in some cases, the element may be destroyed due to insufficient ignition power. There is sex.

[Problem to be solved by the invention]

In conventional technology, the protection of an element is based on the current flowing through the element,
This has been done based on the results of control such as monitoring the voltage sharing of the elements, so-called detection results on the main circuit side.

Furthermore, the gate circuit of the element is used while being connected to a gate active circuit called a gate drive circuit. However, in the past, the output of this gate drive circuit was directly connected to the gate of the element, and there was no function to check the gate pulse, so even if an incomplete gate pulse occurred after the gate drive circuit, it could not be detected. Since no detection is performed, the device is not always sufficiently protected against incomplete gate pulses, and in some cases, the device may be destroyed.

An object of the present invention is to prevent device destruction due to incomplete gate pulses.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a means for constantly monitoring the gate pulse applied to the element, thereby monitoring the application time of the gate pulse to the element and its voltage or current, and adjusting the applied voltage (current). By providing a function that forcibly converts the gate pulse into a predetermined voltage with a predetermined time width and applies it to the element when a predetermined value is exceeded, it is possible to prevent incomplete gate pulses by applying a regular gate pulse to the element. This is to prevent destruction of the element.

[Effect]

The gate pulse monitoring section directly monitors the gate pulse applied to the gate of the element, and detects that the voltage (current) is higher than the minimum firing voltage (current) of the element.

The detection result is given to the gate pulse generator.

Based on this signal, the gate pulse generator generates a gate pulse having the minimum necessary time width for the device and a voltage (current) sufficient for igniting the device.

By superimposing this gate pulse with the gate pulse mentioned above, it is possible to always give a gate pulse with the necessary time and voltage to the device, and this allows the device to be destroyed due to an incomplete gate pulse. can be prevented from occurring.

〔Example〕

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

In FIG. 1, a gate control signal is applied from the control circuit 1 to the gate drive circuit, and the gate drive circuit 2 generates a gate pulse corresponding to the element 7 and applies it to the gate of the element, thereby turning on the element. The configuration is such that off control is performed to control the power applied to the load of the element.

Here, the gate signal of the element is taken into the comparator 5, and the comparator is provided with the gate signal and the comparison reference voltage 4.
This reference voltage is set to the minimum firing voltage of the element.

Therefore, this comparator will check whether the gate signal is greater than or equal to the minimum firing voltage of the element.

If the gate signal is equal to or higher than the minimum ignition voltage, a trigger signal is given to the gate pulse generator 6 connected to the comparator.

In the gate pulse generator, when a trigger signal is given,
A gate pulse of a predetermined time width and a predetermined voltage is generated and applied to the device together with the previous gate pulse.

The output of the gate pulse generator will be input again, so in order to prevent the gate pulse from being generated again, the function here is to use a monostable multi (one shot) It has functions.

FIG. 2 shows a specific circuit example of the embodiment shown in FIG.

The GTO is taken as an example of the controlled element.

The gate pulse of GTO is applied to comparator 8 and comparator 9.

The comparator 8 is used to chienor the ignition pulse of the GTO, and the other input of the comparator is given a reference voltage corresponding to the minimum ignition voltage of the GTO.

Now, when a gate pulse is given to GTO, comparator 8
This gate pulse voltage is compared and the voltage is G.
If it is greater than the minimum firing voltage of TO, the output of the comparator is inverted.

One-shot multivibrator 1 is connected to the output of the comparator.
0 is connected, and a pulse of a predetermined time width is generated based on the output of the comparator.

This pulse width is set to the minimum time required for ignition of the GTO.

This pulse is amplified by the next-stage drive circuit to a voltage necessary for igniting the GTO, and this is applied to the gate of the GTO to turn on the GTO.

The gate pulse generated by this circuit has a pulse width of the minimum time required to turn on the GTO, so when a gate pulse with a long time width is given from the gate drive, the regular gate pulse will be buried. Become,
It has no effect on normal control.

The performance required for GTO gate drive is generally as follows:
A voltage larger than the steady state at the rise of the gate pulse (
Since a capacitor is required on the collector side of the transistor 14 of the drive circuit, this capacitor is charged from the power supply when the GTO is not ignited, and this charge is discharged when the GTO is ignited. The capacity of the power supply section is reduced to achieve the objective.

Resistor 1 connected to the collector side of the transistor
6 is for suppressing the charging current to the capacitor.

When arc-extinguishing the GTO, it is necessary to generate an arc-extinguishing pulse in exactly the same way.

The circuit for this purpose is comparator 9. One-shot multivibrator 11. Transistor 13. This is a capacitor 15 or the like.

The operation is similar to that during ignition, but the polarity of the extinguishing pulse voltage is opposite to that during ignition, so the difference is that the polarity of the reference voltage for comparison is set to be effective from that for ignition.

FIG. 3 shows a time chart showing the operation of this embodiment.

〔Effect of the invention〕

According to the present invention, since incomplete gate pulses can be eliminated, it is possible to obtain the effect of preventing element destruction due to incomplete gate pulses.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
The circuit diagram shown in FIG. 3 is a time chart showing an outline of the operation of FIG. 2. 1... Control circuit, 2... Gate drive, 3...
Photocoupler, 4... Reference voltage, 5... Comparator, 6
...Gate pulse generating section, 7...Element, 8...Comparator, 9...Comparator, 10...One-shot multivibrator, 11...One-shot multivibrator, 12°13. ...+Ran resistor, 14.15...
・Capacitor, 16...Resistor. Figure 1

Claims (1)

[Claims] 1. In a power semiconductor that controls power to a load of an element by applying an ignition or extinguishing pulse signal to the gate, the pulse width and voltage of the gate signal applied to the element are monitored. A power semiconductor protection device characterized by having a function to protect the power semiconductor. 2. In claim 1, the monitoring function converts the gate pulse into a predetermined voltage with a predetermined time width when the signal generates a minimum voltage necessary for ignition of the element defined by the element. A protection device for a power semiconductor, which is provided with a function to provide protection to the element.