Loss Characteristic Analysis of Small and Medium-sized Induction Motors Fed by PWM Inverter Based on the Experiment Measurements

In order to improve the efficiency, we should know the loss characteristics of inverter-fed induction motors. We first have to accurately measure the total motor losses, and then obtain each loss component by reasonably separate the total motor losses. In this paper, the total losses of a 5.5 kW, a 22 kW, a 30 kW, a 37 kW, a 45 kW and a 55 kW induction motors under sinusoidal supply and PWM inverter supply conditions are measured. The total losses of those motor are divided into five parts based on the loss segregation procedure IEEE Std 112-B with some special considerations, such as using AC resistance to replace the dc resistance for taking skin and proximity effect into account. Finally, the characteristics of the stator (IR)-R-2 losses, rotor (IR)-R-2 losses, friction and windage losses (F&W losses), core losses as well as stray-load losses of those motor under sinusoidal supply and PWM inverter supply conditions are analyzed.