A Three-Level Inverter Direct Torque Control of a Permanent Magnet Synchronous Motor

The direct torque control (DTC) technique for a three-phase induction and synchronous motor is receiving increasing attention due to the important advantages as the elimination of the current controllers and the low dependence on motor parameters when compared with other motor control techniques. However high torque and stator linkage magnetic flux ripples and stator voltage and, stator current harmonic contents result when using a two-level inverter with hysteresis controller. This paper presents simulation results of a three-phase permanent magnet synchronous motor (PMSM) fed from a three-level voltage-controlled inverter showing low air-gap flux and torque ripples and reduced stator current and stator voltage harmonic distortion. As far as the authors know this is the first paper showing the benefits of the use of a three-level voltage-controlled inverter in DTC scheme to control the torque and speed of PMSM with the proposed algorithm