Partial Discharge Calibration of Power Module Packaging Insulation Under Square Wave Voltage

Partial discharge detection is an important way to evaluate the reliability of insulation. In order to detect partial discharge of high-voltage power module packaging insulation, it is necessary to calibrate the entire high-voltage circuit. Unlike the traditional partial discharge calibration method under sinusoidal voltage, square wave voltage with high dv/dt can cause strong electromagnetic interference and displacement current on the rising and falling edges, greatly affecting the calibration of discharge quantity. To solve the problem, this paper introduces a partial discharge calibration method under square wave voltage, using non-inductive resistors to acquire the waveform of partial discharge pulse. Taking the parasitic inductance into consideration, the resistors are connected in reverse series to eliminate the mutual inductance. A low-voltage square wave source is then used to calibrate the resistance of the sampling resistor at different voltages. Finally, the apparent discharge quantity of power module packaging insulation under high voltage square wave can be obtained through the integral of voltage on the sampling resistor.