Insulation Tester for Medium Voltage Components Subject to PWM Voltage Stress

A high efficiency insulation tester pulser power supply is presented for evaluating insulation systems subject to pulse-width modulation stresses generated by modern high power converters. A resonant circuit is used with a series inductor inserted at the pulser output to go along with the capacitance of the insulation sample. This approach with accompanying converter topology reduces power supply losses and allows for testing of larger capacitive loads at high switching frequencies. The modular approach is scalable from low voltage to medium voltage applications. Analytical estimates of relevant currents are presented with simulation results followed by experimental results of a prototype pulser supply with a 20 nF load tested to 1200 V.