The Effect of PWM on Rotor Eddy-Current Losses in High-Speed Permanent Magnet Machines

High-speed permanent magnet machines, supplied by pulsewidth modulation (PWM) voltage source inverters, operate with distorted stator currents. Harmonics present in these stator currents deteriorate the machine performance by generating losses. Mostly, these losses are following the machine design using a transient finite-element model. The precise measurement of these rotor eddy-current losses is extremely difficult, hence, only a few papers provide convincing comparisons between predictions and measurements. This paper presents a fast and precise analytical approach, verified with measurements, to consider rotor losses of machines, supplied by PWM voltages, already during the design procedure.