Optimal control of permanent-magnet AC machine drives with a novel multiple reference frame estimator/regulator

With appropriate current waveforms, permanent-magnet synchronous machine (PMSM) drives with arbitrary back EMF waveforms can achieve superior performance in terms of torque ripple and minimal copper loss. This paper sets forth a method to analytically calculate these optimal waveforms. Since tracking errors can seriously degrade performance in this type of system, a novel multiple reference frame synchronous estimator/regulator (MRFSER) is also set forth. This ensures that each harmonic of the optimal waveform, and thus the optimal set point, is precisely achieved. Computer and experimental studies are used to validate the work.