Compensation of Current Harmonics for Switching-Table-Based Direct Torque Control of Dual Three-Phase PMSM Drive

Current harmonics are ubiquitous in dual three phase (DTP) permanent magnet synchronous machines (PMSM) drives. Due to inverter non-linearity and the back electromotive force (EMF) distortion and, significant current harmonics are generated in DTP system. The influence of back EMF harmonics is investigated in this paper and a novel switching-table-based direct torque control (ST-DTC) method to compensate the back EMF harmonics has proposed, thereby reducing the current harmonics. By changing voltage vector active time durations, voltage harmonic injection could be achieved so that the back EMF harmonics could be compensated, as verified by experiments.