Efficiency comparison between motor friendly hard and soft switching inverters

This paper compares two motor-friendly inverters. One is quasi resonant DC-link soft switching inverter and the other one is hard switching inverter together with a filter. The soft switching inverter is designed for reduced dv/dt. With the use of an additional switch, peak common mode voltage is also reduced. In order to evaluate the motor-friendly characteristic of a soft switching inverter, the experimental results regarding the line to line voltage, line to earth voltage and common mode voltage effects on motor fed with long cable are presented. Furthermore, important comparisons with hard switching operation of the same inverter (resonant circuit not operated) with commercially available filters connected at inverter output, regarding the effects and efficiency are presented. Conclusions are then drawn that motor-friendly SS inverter is an alternative to HS inverter with a sine-wave EMC output filter. The motor-friendly soft switching inverter does not need an output filter. So it has good dynamics compare to a hard switching inverter with a sine-wave EMC output filter.