No-load loss separation in induction motors operated by PWM inverters: Numerical and experimental approaches

In the paper an accurate analysis of the different loss contributions active during no-load operations of PWM inverter fed induction motors is presented. In particular, the paper is focused onto the understanding and quantification of the loss growth passing from sinusoidal to PWM supply. Standard no-load tests have been performed on an 11kW, squirrel cage, induction motor to collect reference loss data to be compared with the computed one. The loss estimations have been done using two different approaches. The former is a 3D, time-stepping, FEM model, while the latter is a simplified analytical, experimental data-based approach recently proposed by the authors. Both numerical and semi-analytical methodology lead to accurate results with estimation percentage errors lower than 5 % in the considered voltage range.