This paper investigated the losses and thermal characteristics of induction motors operated from pulse width-modulated (PWM) voltage supply in comparison to that operated from sinusoidal voltage supply. It was concluded that due to the abundant harmonics in the PWM waveforms, significant losses are induced in the motor by the inverter supply. The temperature ascends correspondingly. Switching frequencies of the PWM inverter at 3.5 kHz to 9 kHz were investigated to evaluate their effect on the excessive losses. Experiments were conducted with no load and with load conditions. The losses and thermal characteristics were calculated using finite-element analysis (FEA) and validated by the experiments.
Keywords: finite-element method, FEM, harmonics, pulse width-modulation, PWM, power electronics, frequency converter, induction machine, inverter, losses, thermal