Model Predictive Direct Torque Control of a Permanent Magnet Synchronous Motor for Torque Ripple Reduction

Abstract

This dissertation presents an improved model predictive control (MPC) strategy to reduce the torque ripple and commutation frequency in conventional direct torque control (DTC) of the permanent magnet synchronous motor (PMSM) Nowadays DTC has been widely used in industrial applications thanks to its simple structure and high dynamic performances However hysteresis controllers cause high torque ripple and variable switching frequency In this novel method hysteresis controllers and the switching table are replaced with a model predictive controller base online optimization for the selection of voltage space vector among the possible ones Furthermore a pre-selective process is designed to filter out the inappropriate voltage vectors to reduce the computational burden caused by the eight basic voltage space vectors Then apply duty ratio modulation to determine the operating time of the selected voltage vector and zero voltage vector in one sample period for torque ripple reduction By implementing the proposed DTC torque ripple is reduced and the approximated switching frequency can be minimized to retain the advantages of a conventional DTC; meanwhile the torque response is still quick Both simulation and experimental results exhibit the effectiveness of this proposed approach

Date of Award	2019
Original language	English
Supervisor	Mi-Ching Tsai (Supervisor)