Synchronous frame phase compensation for applying modulated model predictive control to high-speed motors

This paper proposes a phase compensation in the synchronous frame for applying modulated model predictive control (MMPC) to a high-speed motor. In the conventional MMPC, when future values for the control variable are predicted, it is necessary to assume that the other variables have constant values during one sample period. However, under a high electrical frequency, this assumption provokes a prediction error, which affects the steady state response. Hence, to improve the precision for predicting variables, the phase variation in the synchronous frame is analyzed and compensation methods are proposed. In particular, the instantaneous variance for the back electromotive force during one sampling period is analyzed, and a compensation method for its variance is derived. To validate the effectiveness of the proposed compensation methods, a motor drive system that can be operated at 3000 rpm is built and tested. Simulation and experiments are performed while comparing the transient and steady state responses.