A study is described of the system loss in a transistorized pulse width modulated (PWM) inverter and induction motor. The losses include inverter switching loss, invertor conduction loss, fundamental frequency motor loss, and motor harmonic loss. Inverter efficiency and motor efficiency have a trade-off with respect to chopping ratio, the maximum system efficiency exists at a certain chopping ratio.
The motor phase current waveform, frequency spectrum, and the chopping ratios which make the maximum system efficiency for each stator frequency are simulated by VAX 11-780 computer.
By experiment, motor phase current waveform and frequency spectrum are observed for each chopping ratio and are compared with the simulation results.
