Eddy-Current Losses evaluation in hairpin wound motor fed by PWM Inverter

This paper presents different approaches proposed to evaluate eddy-current losses in hairpin wound motor fed by pulse width modulated inverter, underlining strengths and weaknesses of everyone and applying them, as test-case, to a 200kW induction motor designed for a premium electric vehicle.The first three approaches are based on the finite element analysis: the first, the more accurate one, use a transient analysis that request long execution time and high memory usage, the second is based on tool that permits rapidly to evaluate the steady state conditions imposing a sinewave current and the third uses a single-slot simplified model. The fourth approach proposes a rapid monodimensional analytic method based on hypotheses that permit to consider the superposition effects of the Eddy-Current Losses of every current harmonic component. The fifth approach makes uses of the proposed analytic method by leveraging a rapid investigation of current harmonic content due to pulse width modulation based on a lumped parameter motor model.In addition, the paper discusses important considerations about the use of the hairpin technology fed by pulse width modulation that can be drawn from the analysis of the obtained results.