Rapid analytical method to evaluate eddy current losses in hairpin wound im due to PWM

This paper proposes a rapid and analytical approach to evaluate the steady-state eddy-current losses in hairpin wound induction motors fed by pulse width modulated inverter. The method is based on a custom frequency-dependent lumped parameter circuit, useful to evaluate the steady-state harmonic content of the phase current considering the modulation. Furthermore, simplifying hypotheses, suitably described and justified, allow the definition of an analytical model for the calculation of the Joule losses contribution for each harmonic considering the effect of eddy-currents. This proposed approach is compared with the computationally more expensive transient finite element method and applied, as test-case, to a 200kW induction motor designed for an electric vehicle. A realistic estimation of the method accuracy and computational time is provided in a practical case, as well as a quantitative evaluation of the eddy current losses due to the modulation.