JPH06167533A - Switching test circuit for self arc extinguishing element - Google Patents

Abstract

PURPOSE:To improve difficulty in evaluation of a relationship with reverse restoration characteristic of a circulation diode by setting the current of the circulation diode for circulating a load current independently at an arbitrary value in the testing and evaluating a switching operation of a self arc extinguishing element under inductive load conditions. CONSTITUTION:A circulation diode 10 connected in series to a circulation power source capacitor 11 is set at both ends of a inductive load device 3 and a DC power source 12 for a circulation circuit is provided at both ends of the capacitor 11 to form a load circuit. A voltage of a DC power source 12 for the circulation circuit is adjusted with a testing circuit which has a DC power source 1, the load circuit and a self arc extinguishing type element 5 as a sample element connected in series individually. A circulation current value is set previously by adjusting the voltage of the DC power source 12 for the circulation circuit thereby evaluating the behavior of the self arc extinguishing element 5 under an inductive load.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a bipolar transistor, an insulated gate transistor, an SI thyristor and a G transistor.
The present invention relates to a switching test circuit for a self-extinguishing element such as a TO thyristor.

[0002]

2. Description of the Related Art Conventionally, a switching test of a self-arc-extinguishing element is performed by switching a self-arc-extinguishing element from a DC power source with a load device as a pure resistance or by connecting the load device as an inductive load in parallel with the load device. It is configured so that the load current can be circulated by providing a freewheeling diode to switch the self-extinguishing element, and the behavior depending on the magnitude of the voltage or load current applied to the self-extinguishing element itself can be changed to the operation speed or switching. Tests have been conducted for the purpose of evaluating self-extinguishing type devices by measuring characteristic values such as loss.

An example of this type of prior art will be described below with reference to the drawings.

FIG. 7 is a test circuit diagram showing a configuration relating to the present application of a switching test circuit for a self-arc-extinguishing element according to the prior art.

In FIG. 7, a direct current power supply 1 passes through a backflow prevention diode 2, a load device 3 which is generally composed of a resistor and a reactor as an inductive load, and a self-extinguishing element is turned on. It is composed of a series circuit formed by an air-core reactor 4 simulating the stray inductance of the wiring provided for adjusting the current increase rate and a self-arc-extinguishing element 5. Here, the gate driving device 6 is a device that controls the gate of the self-turn-off device 5, and the snubber diode 7, the snubber capacitor 8 and the snubber resistor 9 are snubber circuits for protecting the device under test. When the freewheeling diode 10 connected in parallel to the load device 3 turns on the self-extinguishing element 5 when the energy stored in the reactor of the load device that is assumed in the application of the self-extinguishing element is turned on,
It is provided for the purpose of evaluating the influence of the reverse recovery characteristics of the diode.

The operation of FIG. 7 will be described below with reference to the operation explanatory diagrams of FIGS. 3 to 5 showing the current waveform of the load device 3. Note that FIG. 5 is an enlarged view of the range from the period t0 to t1 in FIG.

In FIG. 7, when the switching operation cycle of the self-arc-extinguishing element 5 is sufficiently short with respect to the time constant due to the resistance value of the resistor included in the load device 3 and the inductance of the reactor, the current of the load device 3 is reduced. Is as shown in the operation explanatory view of FIG.

That is, when the self-arc-extinguishing element 5 is turned on, among the load currents, the periods t0 to t1 and t2 in FIG.
.About.t3, t4 to t5, the current waveform portion indicated by the symbol Is becomes the current of the self-arc-extinguishing element 5. Of this current waveform, the portion including the peak current Ip portion in the period t0 to t01 in FIG. 5 is from the positive electrode of the DC power supply 1 to the freewheeling diode 10, the air-core reactor 4, the self-extinguishing element 5, and the negative electrode of the DC power supply 1. This is a period in which a reverse voltage is applied to the freewheeling diode 10 along the route and a large reverse recovery current of the freewheeling diode is flowing.

On the other hand, when the self-arc-extinguishing element 5 is turned off, the current of the load device 3 is from the period t1 of the shaded portion in FIG.
The current waveform is represented by the symbol Id of t2, t3 to t4, and the load current circulates as the current of the freewheeling diode 10.

That is, assuming that the freewheeling diode is an ideal element having no reverse recovery current, the current indicated by the above-mentioned symbol Ip does not flow, and the current waveform of the symbol Is has an initial value of Iv,
The current waveform has a final value Im, and the rate of increase in current is determined by the ratio of the power supply voltage of the DC power supply 1 and the inductance of the load device 3 in FIG. Further, the current waveform of the symbol Id decreases as the freewheeling diode current according to the damping time constant due to the resistance and the inductance in the freewheeling circuit formed by the load device 3 and the freewheeling diode, and the current is turned on by the self-extinguishing type element. At the value Iv, the forward current of the freewheeling diode ends.

Accordingly, the test target value of the turn-on current of the self-extinguishing element 5 becomes Ip which is the value obtained by adding the reverse recovery current of the freewheeling diode to Iv, and the target value of the turn-off current test is set to Im.

However, in the circuit of FIG. 7, when the self-extinguishing element 5 has a short ON period and a long OFF period and the time constant due to the inductance of the resistor and the reactor included in the load device 3 is short, The freewheeling current of the arc extinguishing element 5 does not flow continuously and is attenuated. Therefore, the current of the load device 3 does not flow at the turn-on timing of the self-extinguishing element 5, and it becomes an intermittent current as shown in FIG. 4, and the turn-on current always has a waveform rising from zero. It is not possible to conduct a test with a given current value. Further, in this case, since the reverse voltage is applied to the freewheeling diode at the timing when the forward current of the freewheeling diode does not flow, the reverse recovery current of the freewheeling diode does not flow.
Also, the test under the condition that the peak current Ip shown in FIG.

[0013]

Therefore, as is clear from the above description, in the case of the conventional test circuit shown in FIG. 7, the self-arc-extinguishing element 5, which is the device under test, is not turned on or off. In order to apply the applied voltage and current value that match the predetermined target test conditions as test conditions, the constants of resistors and reactors are switched and the switching operation cycle is changed and set each time in order to change the time constant inside the load device. As a result, the test equipment is poor in the independent setting of the test conditions that the test equipment should have. Furthermore, in order to set the turn-on current value Iv to a predetermined value other than zero,
Since it is not possible to realize such an intermittent waveform as described above, it is necessary to repeatedly operate the device under test or to separately provide a load current setting control device in parallel with the device under test to make the current of the load device 3 a continuous current. .

In the former case, the load current causes self-heating due to the loss of the device under test, making it difficult to set the test junction temperature to a predetermined value. In the latter case, there is a defect that the test device is more than the test device and it is necessary to install a control element having a capacity capable of withstanding repeated operations, which makes the test device complicated and large.

An object of the present invention is to set a test junction temperature as a test condition to be given to a device under test in a switching test of a self-arc-extinguishing device while arbitrarily setting it by an external heating means without depending on self heating of the device. It is an object of the present invention to provide a simple and convenient test apparatus in which the conditions of applied voltage and current can be arbitrarily and independently set, and the characteristic changes of the device under test can be pursued due to changes in various conditions.

[0016]

According to the present invention, the object is to insert a freewheeling power supply capacitor in series with a freewheeling diode and connect a DC power supply for a freewheeling circuit, which is a low voltage variable power supply, to both electrodes of the freewheeling diode. By doing so, the loop of the load device, the freewheeling diode, and the freewheeling capacitor is continuously and arbitrarily supplied with a direct current, and the switching operation of the self-arc-extinguishing element itself, which is the device under test, is single-shot, or It can be achieved as a very low frequency operation.

[0017]

[Function] By providing the circulating power supply capacitor and the DC power supply for the circulating circuit, the time constant due to the resistance value and the inductance in the DC power supply and the load device is provided in the loop formed by the load device and the circulating diode including the capacitor. The circulation current can be independently set to an arbitrary constant value only by adjusting the voltage of the DC power supply for the circulation circuit, without being affected by the mutual relation with the operation cycle of the element.

Therefore, when the operation of the self-extinguishing element of the device under test is driven sporadically or during the driving of an extremely low frequency for a short period, heat is generated by one switching operation of the device under test. Since the setting value of the joining temperature by the external heating means of the test element is hardly affected, the setting of the joining temperature can be set almost independently. Therefore, as a switching test device for the self-extinguishing type element, it is possible to obtain a test device that can be independently set and a simple test device.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a switching test device for a self-extinguishing type element according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a basic circuit diagram of a switching tester for a self-extinguishing type element according to the present invention. In FIG. 1, reference numeral 1 is a DC power source for applying an applied voltage or load current to the device under test immediately before turn-on, 3 is a load device composed of a reactor having a very small electric resistance, and 4 is a load device when the device under test is turned on. It is an air-core reactor for adjusting the rate of current rise, and at turn-off, the overshoot amount Vp of the voltage shown in FIG. 6 can be given as a test condition for the device under test. The overshoot amount Vp increases due to an increase in the inductance of the air-core reactor 4 and the current of the device under test, and decreases due to the increase in the capacity of the snubber capacitor 8 and the loss in the device under test and the test circuit. Therefore, by adjusting the inductance by, for example, providing a tap on the air-core reactor 4, a predetermined overshoot amount V
It can be p.

Reference numeral 5 is a self-arc-extinguishing element which is a test element, and 7, 8, and 9 are snubber diodes, snubber capacitors, and snubber resistors for protecting the test element 5, respectively.
Reference numeral 10 is a freewheeling diode, and 13 is a DC power supply.

FIG. 2 is a circuit diagram showing an embodiment based on FIG. 1, and the configuration and operation will be described with reference to FIG. In FIG. 2, reference numeral 2 is a backflow prevention diode, and 6 is a gate drive device for the self-turn-off element 5. Further, instead of the DC power supply 13 of FIG. 1, a circulating power supply capacitor 11 and a circulating circuit DC power supply 12 are arranged in parallel and used.

In FIG. 2, in order to apply the test current waveform of FIG. 3 to the self-arc-extinguishing element 5 of the device under test, the circulating power source capacitor 11 is charged from the circulating circuit DC power source 12, and the circulating diode 10 is charged from this capacitor. Through load device 3
A DC current of a predetermined value is continuously supplied to the device in advance. As a result, even if the device under test is driven and turned on by itself like the test current waveform of FIG. 3, a voltage is applied from the DC power supply 1 to the reverse direction of the freewheeling diode 10 via the reverse current prevention diode 2. As a result, it becomes a reverse recovery current of the freewheeling diode, and a test current having a peak value Ip can be applied to the self-arc-extinguishing element 5 via the air-core reactor 4. Therefore, the test junction temperature of the self-arc-extinguishing element 5 can be evaluated as a condition given almost externally, not by self-heating.

If an ideal element having no reverse recovery current is used as the freewheeling diode, the current immediately after turning on the self-extinguishing element 5 depends on the voltage of the DC power supply 1 and the inductance of the air-core reactor 4. The self-arc-extinguishing element 5, which is the device under test, is given a current waveform that rises at a current increase rate determined by the ratio and is limited to the current value Iv. Therefore, when evaluating for various current values Iv By adjusting the output voltage of the DC power supply 12 for the free-wheeling circuit, the current value Iv can be adjusted arbitrarily to easily evaluate the current value dependency immediately after the self-turn-off element 5 is turned on. be able to.

Further, as a matter of course, when evaluating the relationship with the characteristics of the freewheeling diode 10 having various reverse recovery characteristics as the evaluation of the turn-on characteristics of the self-extinguishing element 5, it is easy to replace the freewheeling diode. It can also be evaluated.

After the self-arc-extinguishing element 5 is turned on, the self-arc-extinguishing element 5 is turned on at a current increase rate substantially determined by the ratio of the voltage of the DC power source 1 to the inductance in the load device. It rises and reaches the current value Im. Therefore, the turn-off test current value of the self-extinguishing element 5 becomes Im. This current value becomes the initial value of the forward current for the freewheeling diode and causes the load device 3 to circulate. Therefore, in order to set the test condition focusing on the turn-off condition of the self-extinguishing element 5,
The current value Im can be set as the target test condition value by adjusting the voltage of the DC power supply 12 for the circulation circuit as in the case of the turn-on described above.

In order to evaluate the self-arc-extinguishing element 5 by giving a rectangular wave-like waveform with the current value Im in FIGS. 3 and 5 as close as possible to the current value Iv, the load device 3 must be evaluated. Self-extinguishing element 5 by increasing the inductance of
By sufficiently shortening the energization period of 2 compared to the operation repetition cycle, the increase of the load current can be suppressed and the purpose can be achieved.

Further, as is clear from the above description, the self-extinguishing element 5 is driven by a single drive cycle or is driven at a low frequency of, for example, about 10 hertz or less. If the ON period of the arc-shaped element 5 is made sufficiently short as compared with the driving cycle, the change in the junction temperature due to self-heating of the element is not so large and the independence of test conditions is not impaired.

The present invention is intended for efficient evaluation of the self-arc-extinguishing element 5, and is provided with at least the voltage across the self-arc-extinguishing element 5, the current, and the base, or the gate voltage and the current measuring means. By storing the waveform of any period that is driven by a single shot or low frequency as described above, based on each waveform data obtained by the switching test of the self-extinguishing type element, time display of operating speed, calculation of loss, etc. It is even more effective in that it can be processed and the characteristics of the devices under test can be compared.

[0030]

As described above, according to the present invention,
Since test conditions can be given independently, transistors, GTO thyristors, SI thyristors, IGBTs
A simple and efficient self-extinguishing element, especially when improving the element characteristics, because the behavior of various element characteristics with respect to the inductive load of the self-extinguishing element such as (insulated gate bipolar transistor) can be evaluated. It is possible to provide the switching test device.

[Brief description of drawings]

FIG. 1 is a basic circuit diagram of a switching test device for a self-arc-extinguishing element according to the present invention.

FIG. 2 is a circuit diagram showing an embodiment based on FIG.

FIG. 3 is a test current waveform given to a device under test for explaining the operation of the present invention and the operation of a conventional test apparatus and for a switching test of a self-turn-off device.

FIG. 4 is an explanatory diagram of operation waveforms for explaining an operation under a special condition where the circulating current is zero according to the related art and the present invention.

5 is an enlarged view of a current portion of a device under test in the operation current waveform of FIG.

6 is a waveform diagram of the voltage of the device under test corresponding to FIG.

FIG. 7 is a test circuit diagram of a conventional switching test device for a self-extinguishing element. 1 DC power supply 2 Backflow prevention diode 3 Load device 4 Air-core reactor 5 Self-extinguishing type element 6 Gate drive device 7 Snubber diode 8 Snubber capacitor 9 Snubber resistor 10 Freewheeling diode 11 Freewheeling power supply capacitor 12 DC power supply for freewheeling circuit 13 DC power supply

Claims (4)

[Claims] 1. A direct current power supply, a backflow prevention diode, a load device, an arrangement in which a freewheeling diode having a cathode opposed to a positive electrode of a direct current power supply is arranged in parallel with the load device, an air-core reactor, and a self-extinguishing element. And are connected in series,
In a test circuit for testing the switching characteristics of a self-extinguishing element by turning on and off the element itself, a freewheeling capacitor is arranged in series with the freewheeling diode, and the freewheeling diode and the freewheeling diode are connected to the freewheeling capacitor. A switching test circuit for a self-extinguishing element, characterized in that it is configured by connecting a DC power supply for a circulating circuit that supplies a circulating current that matches the rectifying direction of the circulating diode to a loop loop formed by a capacitor and a load device. . 2. A switching test circuit for a self-extinguishing element according to claim 1, wherein the power supply for the freewheeling circuit is provided with means for adjusting the freewheeling current. 3. A self-extinguishing element switching test circuit comprising a gate driver configured to drive the operation of said self-extinguishing element in a single shot or at a low frequency of about 10 hertz or less. 4. The self-extinguishing element is provided with at least a voltage across both ends, a current, a base or a gate voltage and a current measuring means, and the operation of the self-extinguishing element is performed once or about 1.
2. A switching test circuit for a self-arc-extinguishing element according to claim 1, wherein a waveform of an arbitrary period driven at a low frequency of 0 hertz or less is stored.