JPH0419505Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a reverse current testing device for maintenance and inspection of high-voltage semiconductor rectifiers, semiconductor-controlled rectifiers, etc.

[Prior art and its problems]

In many cases, the quality of a semiconductor rectifying element can be determined by measuring the reverse current. For example, products with extremely large reverse currents, large history loops, unstable characteristic curves, etc. are generally determined to be deteriorated or defective. Therefore, the determination of reverse current is also used as a method of determining the quality of the characteristics of semiconductor rectifying elements during maintenance and inspection of power converters. Maintenance and inspection of power conversion equipment involves measuring the reverse current of a large number of semiconductor rectifying elements individually, so a testing device that is easy to use and that can obtain accurate characteristic values in a short period of time is required. It is being

FIG. 1 is a connection diagram of a conventional reverse current testing device. In the figure, 1 is a voltage regulator connected to an AC power supply, 2 is a step-up transformer, 3 is an auxiliary rectifier, and 4 is a voltage regulator connected to an AC power supply.
5 is a cathode ray tube oscilloscope, 6 is a current shunt, and 7 is a resistive voltage divider. In the above connection diagram, the AC voltage adjusted to the test voltage specified for the semiconductor device under test 4 by the voltage regulator 1 and step-up transformer 2 is only a half-wave voltage when the auxiliary rectifier 3 is in the conductive state. is applied to the semiconductor device under test 4. At this time, the reverse current flowing through the element 4 is detected by the shunt 6 and applied to the vertical axis input circuit of the cathode ray tube oscilloscope 5, and the reverse voltage applied to the element 4 is detected by the resistive voltage divider 7 and sent to the cathode ray tube oscilloscope. The signals are respectively input to the horizontal axis input circuit of the oscilloscope 5, and the reverse current-voltage characteristics of the device under test 4 are displayed on the tube surface of the cathode ray tube oscilloscope 5.

However, when the semiconductor device to be tested is a power device, the test voltage peak value is several thousand volts. For this reason, the step-up transformer 2 and voltage regulator 1 that step up the commercial frequency power supply voltage to the test voltage are large and heavy, and the cathode ray tube oscilloscope is also quite large, making the entire test equipment large and heavy. Although it is suitable for use as a stationary type in factory tests, etc., it has a drawback that it is not suitable for carrying and using the test device near the device to be tested at the place where the converter is installed. Further, in order to obtain the reverse current of the element 4, it is necessary to photograph the surface of the cathode ray tube, read data from the photograph, and analyze measurement data such as conversion of data using a division ratio and a division ratio. For this reason, it takes time to judge the test results, and during maintenance inspections that require judgment of the acceptability of a large number of rectifying elements installed inside the converter, problems such as having to stop the operation of the converter for a long time occur. There were some shortcomings.

[Purpose of invention]

This idea was made in view of the above situation.
The present invention aims to simplify and speed up the maintenance and inspection work of large-capacity converters by providing a reverse current test device for semiconductor rectifier elements that is small and lightweight and allows direct reading of measurement results.

[Key points of the idea]

According to the present invention, the above-mentioned purpose is to use a triangular wave test voltage having a peak value equal to the peak value of the AC half-wave voltage instead of the conventional AC half-wave test voltage, and the control unit receives a test start signal. receive and send 1
A converter converts the low voltage triangular wave voltage signal into a high frequency oscillating voltage having twice the amplitude of the triangular wave voltage signal, and a high frequency transformer converts this high frequency oscillating voltage so that the peak value is equal to the peak value of the triangular wave test voltage. By configuring the test voltage generator to rectify the boosted oscillating voltage to obtain a triangular wave test voltage, the test voltage generator can be made smaller.
Furthermore, this is achieved by providing a peak value detection section and a display section that detect and display the peak value of the test voltage and the peak value of the reverse direction current that appears correspondingly, so that the measurement results can be immediately known. It was done.

[Example of idea]

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

FIG. 2 is a connection diagram of a test device showing an embodiment of the present invention. In the figure, reference numeral 11 denotes a control section, which is configured to generate one triangular wave voltage signal in response to a signal input to the test start signal input electrical contact 11a. 11b is configured to charge at a constant current. Reference numeral 12 denotes a waveform converter that receives the output triangular wave voltage signal of the control unit 11 and converts it into a high frequency oscillating voltage having twice the amplitude of the output triangular wave voltage signal. For example, a rectangular wave inverter is used, and 10 ^-4 to 10 ^-3 It outputs an oscillating voltage having an oscillating period on the order of seconds and a waveform whose envelope is substantially equal to and symmetrical in positive and negative directions with the aforementioned triangular wave voltage signal. 13 is a high-frequency transformer, which is a step-up transformer that receives the output oscillating voltage from the converter 12 and outputs a high-voltage oscillating voltage.By shortening the oscillating period of the oscillating voltage, the iron core of the transformer is significantly smaller than before. has been done. High frequency transformer 13
The peak value of the oscillating voltage boosted by be done.
Reference numeral 14 denotes a triangular wave test voltage generator, which is formed to rectify the output oscillating voltage of the high frequency transformer 13 into both waves using a high voltage rectifier, and its output voltage waveform has the same peak value arrival time as the output triangular wave voltage signal of the control unit 11. It becomes a high voltage triangular wave voltage. The triangular wave test voltage is applied to the semiconductor device under test 4 via the output terminal 14a. 6 is a detector for detecting the reverse current of the device under test 4, and 7 is a resistor voltage divider for detecting the triangular wave test voltage, which is adjusted to a predetermined level by the detector 6 and resistor voltage divider 7. The reverse current and triangular wave test voltage are detected by the peak value detection section 8a.
and 8b, respectively. The peak value detection units 8a and 8b each have a function of detecting the peak value i _P of the reverse direction current and the peak value V _P of the triangular wave test voltage and temporarily holding the respective values, and display devices 9a and 9b such as digital meters. The peak value i _P of the reverse direction current, the peak value V _P of the triangular wave test voltage, or the current value and voltage value proportional thereto are displayed respectively.

Furthermore, if the peak value detection unit 8a is configured to have a determination function that issues an abnormality alarm signal when the peak value i _P of the reverse direction current detected exceeds a predetermined level, it is possible to maintain the large capacity converter. This is convenient because the work of picking out elements with poor characteristics from among a large number of semiconductor rectifier elements during inspection can be carried out more efficiently.

FIG. 3 is a conceptual diagram of output waveforms of each part in the above-described embodiment. In the figure, A is the output triangular voltage signal waveform of the control unit 11, which is a low voltage pulse of 1/n of the peak value V _P of the triangular wave test voltage, and the peak V _P /
The rise time t _P until reaching n is set to about 5 to 10 milliseconds in consideration of the time to reach the peak value of the commercial frequency half-wave voltage. B is the output oscillating voltage waveform of the converter 12, which is a high frequency oscillating pulse with an oscillating period τ of about 10 ^-4 to ^{10 -3} seconds. C is the output oscillating voltage of the high-frequency transformer, and its peak value is boosted to the peak value V _P of the triangular wave oscillating voltage. d is the output triangular wave test voltage waveform of the test voltage generator 14, and e is the waveform detected by the detector 6 of the reverse current of the semiconductor device under test 4. In general, the current is generated in synchronization with the peak value V _P of the triangular wave test voltage. A peak value i _P is detected.

Further, in the embodiment shown in FIG. 2, a high voltage probe and a detection probe connected to the terminal 14a are provided and brought into contact with both terminals of the device under test 4, and the input electrical contact 11a of the test start signal is connected to the probe using an extension cord. If the electrical contact is placed close to the converter and the test operator operates the electrical contact, it is convenient because the test can be carried out without bringing the test device into the converter.

[Effect of idea]

According to the present invention, first, as a primary voltage source of a high-frequency transformer, a control unit that charges a capacitor with a constant current using a variable control rectifier and generates a triangular voltage signal, and a control unit that generates a triangular voltage signal by oscillating this voltage with a predetermined period. By configuring the converter with a converter consisting of an inverter or the like that converts the voltage, a voltage regulator such as a slide transformer in conventional devices is no longer necessary, contributing to making the device smaller and lighter. Furthermore, by using a high-frequency transformer to step up the high-frequency oscillating voltage to a high-voltage oscillating voltage, it is possible to significantly downsize the iron core compared to a commercial frequency step-up transformer. This contributed to making it smaller and lighter. Furthermore, by using a compact instrument such as a digital meter as a measurement value display, a cathode ray tube oscilloscope is no longer required, and in conjunction with the miniaturization of the test voltage generation section mentioned above, the entire test equipment can be made smaller and lighter. I was able to do that.

In addition, by generating the triangular wave test voltage only once, applying it to the device under test, and displaying the peak value of the test voltage and reverse current, it is possible to know the measurement results at the same time as the voltage is applied.
The time required to analyze data has been significantly shortened, making it possible to efficiently perform maintenance and inspection of a large number of rectifying elements in, for example, a large-capacity converter. In particular, when it is necessary to check whether there are any abnormalities in the individual rectifying elements in the event of a short-circuit accident on the load side of the converter, the ability to measure the reverse current in a short time reduces the downtime of the equipment. , is expected to have the effect of reducing losses in production activities.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram of a conventional test device, FIG. 2 is a connection diagram of a test device according to an embodiment of the present invention, and FIG. 3 is a conceptual diagram of output voltage and current waveforms of various parts of the test device. In the figure, 4...semiconductor element under test, 6...
Reverse current detection unit, 7...Voltage divider, 11...Control unit, 12...Waveform conversion unit, 13...High frequency transformer, 14...Test voltage generation unit, 11a...Test start signal input contact, 14a ...Output terminal, 8a, 8
b...peak value detection section, 9a, 9b...display section,
It is.

Claims (1)

[Scope of utility model registration request] A test device for measuring reverse current of a semiconductor rectifying element includes a control unit that generates one unipolar triangular wave voltage signal in response to a test start signal, and a controller that receives this triangular wave voltage signal and generates a unit that is twice the triangular wave voltage signal. a transducer that emits a bipolar oscillating voltage having an amplitude of
A high-frequency transformer boosts this oscillating voltage to a high-voltage oscillating voltage, and rectifies the output voltage of this high-frequency transformer to generate a single high-voltage unipolar triangular wave test voltage whose peak value arrival time is equal to the unipolar triangular wave voltage signal. a test voltage generating section, a detector provided in an output circuit of the test voltage generating section and detecting a reverse current due to application of the triangular wave test voltage of the device under test, and a voltage divider detecting the triangular wave test voltage;
A peak value detection section having a function of detecting and holding the respective peak values of the reverse current and the triangular wave test voltage provided corresponding to the detector and the voltage divider, respectively, and a peak value detection section corresponding to the peak value detection section, respectively. 1. A semiconductor rectifying device testing device comprising: a display device that displays measured values proportional to the reverse current of the device under test and the peak value of the test voltage provided therein.