Modeling the impact of rotor movement on non-linearity of motor currents waveforms in high-speed PMSM drives

Motor current measurement techniques as well as predictive control algorithms for electric drives rely on an assumption of linear motor currents changes resulting from constant inverter output voltages. Recent research has reported that this assumption does not hold in motors with short electrical time constant, and in drives whose rotor position advances substantially during a control period. This paper proposes a simulation model that reflects the non-linearity of currents waveforms. The hybrid model, designed in Matlab/Simulink, consists of both continuous- and discrete-time subsystems. Operation of the inverter can be reproduced in either a simplified manner — by reflecting only the fundamental voltage component, or in detail — by modeling the pulse-width-modulated motor voltages. The proposed model is validated with respect to reproducing the non-linearity of currents waveforms by comparison with a laboratory high-speed PMSM drive.