Capacitance test circuit and test method under DC bias condition

Abstract

The invention discloses capacitance test circuit and test method under a DC bias condition. The circuit comprises a DC voltage stabilizing power source, an inductor, a diverter switch, a first capacitor, a second capacitor, an impedance tester and a bidirectional diverter switch. The DC voltage stabilizing power source and the inductor are connected in series and then are connected with a capacitor to be tested through the diverter switch; the first capacitor and the second capacitor are connected with the two ends of the capacitor to be tested, and the impedance tester is connected between the first capacitor and the second capacitor through the bidirectional diverter switch. The method comprises: switching on the diverter switch, connecting the bidirectional diverter switch to one end of the second capacitor, and charging the capacitor to a stable value; and then connecting the bidirectional diverter switch to the impedance tester, switching to an impedance test state, adjusting the impedance tester to obtain impedance, and then calculating to obtain the impedance of the capacitor to be tested. According to the invention, a charging process and an impedance test process can be switched, the impedance characteristics with in a wide DC bias scope and a wide frequency scope can be measured, and the impact caused by charging and discharging currents of the capacitor to the impedance tester is eliminated.

Description

technical field [0001] The invention relates to a capacitance test circuit and a test method under DC bias voltage, belonging to the technical field of electronic test circuits. Background technique [0002] At present, integrated EMI filters such as planar type, flexible PCB structure type, and busbar type suitable for power electronics applications have been extensively studied. In the integrated EMI filter, the capacitor is an important part, and the high dielectric constant material is the basic material for making such a capacitor. In the process of screening the materials, it is necessary to test the electromagnetic characteristics of the materials in the power electronics application environment, including the performance test under the electric field. The existing test methods are as follows: Use an impedance test instrument with a DC bias power supply (such as LCR impedance test instrument) for direct measurement, this method can be used for small signal test under...

AI Technical Summary

Problems solved by technology

In the process of screening the materials, it is necessary to test the electromagnetic characteristics of the materials in the power electronics application environment, including the performance test under the electric field. The existing test methods are as follows: Use an impedance test instrument with a DC bias power supply (such as LCR impedance test instrument) for direct measurement, this method can be used for small signal test under low DC bias, but its DC bias voltage usually does not exceed 100V; series bridge test method, can be used for small signal test under DC bias Signal test, the test frequency is low (50Hz ~ 10kHz), and the charging current of the capacitor will have an impact on the instrument, and the life of the instrument is low; an RCD snubber circuit method that uses the current and voltage waveforms of the capacitor charging and discharging process to calculate, this method Large-signal testing of several kV can be performed, but the working frequency is only a few Hz, and the test waveform is a triangular wave, which cannot accurately describe the characteristics of the sine wave

Therefore, the existing capacitance test circuit under DC bias has limitations

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