Analysis and Experimental Results of Squarewave Current Shaping for Reducing Commutation Torque in SPM Motors

In several applications where electrical motors are used, the torque ripple must be avoided, since it causes vibrations and acoustic noise. This paper deals with the analysis of the torque ripple of surface-mounted permanent magnet motors fed by squarewave currents. Differently from the previous works, the non-ideal induced back e.m.f. waveform is considered and the current commutation is emphasised. This analysis allows some remedial strategies to be identified, in order to minimise the commutation torque ripple. Simulations and experimental results are reported, confirming the goodness of the proposed strategies.