Complete suppression of torque ripple in BLDC machines caused by back emf and dead time

Abstract—This paper introduces a novel algorithm for suppresion of phase current harmonics in three-phase brushless dc motors caused by non-ideal back-emf waveform and dead-time effects. Proposed feedback acquisition chain obtains an exact information on all the relevant harmonics within each period of the fundamental. Design of the harmonic regulator based on the internal model control principle is given. The paper outlines the relevant details of implementation and the results of verification performed by both computer simulations and experimentally, using a laboratory prototype machine. Experimental results conducted in presence of non-sinusoidal back-emf and with erroneous dead time compensation prove the ability of the proposed solution to remove the stator current harmonics quickly, in just two fundamental periods.