PWM drive filter inductor influence on transient immunity

Surges of less than 200% magnitude caused by utility capacitor switching can disrupt PWM drives. In this paper, the disruption mechanism is investigated by SPICE simulation of the drive and the results are compared to field tests. An overcurrent surge in the rectifier/filter section and DC overvoltage are the most common disruption mechanisms. The drive DC filter inductor is the most important factor in capacitor transient sensitivity of the drive. A drive without the inductor or one in which the inductor is saturated by the transient is vulnerable to disruption.