Optimized waveform control for an 8/6 switched reluctance motor drive

Optimized shaping of the stator current in the switched reluctance motor drive can be used to mitigate electromagnetic torque ripple and decrease the RMS current. Previously, optimal current waveshaping has been based upon defining the optimal current waveform as a set of discrete points and interpolating intermediate points. In this work, an alternate approach is employed in which the current waveform is treated as a set of harmonic coefficients, rather than as an array of discrete values. This has advantages in terms of computation speed and in programming of the microcontroller. A second feature of this new method is that it incorporates a multiple reference frame estimator/regulator that ensures each harmonic of the current converges to its optimized command value thereby avoiding the degradation in performance associated with imperfect tracking that standard current regulation methods are susceptible to. The experimental and simulated results demonstrate the optimality of the waveforms and the importance of the multiple reference frame control, particularly in mitigating torque ripple.