A Novel Direct Torque Control of Matrix Converter-Fed PMSM Drives Using Duty Cycle Control for Torque Ripple Reduction

A novel direct torque control (DTC) strategy using duty cycle optimization is proposed for matrix converter (MC)-based permanent-magnet synchronous motor (PMSM) drive system, which is characterized by low torque ripples, no need for rotational coordinate transformation, and fixed switching frequency. Analytical expressions of change rates of torque and flux of PMSM as a function of MC voltage vectors are derived. An enhanced switching table is established by means of discretization and averaging, in which changes of torque and flux caused by voltage vectors are shown explicitly. Then, the proposed MC-fed DTC algorithm is implemented based on the table. Numerical simulation and experiments with a prototype are carried out. Both simulation and experimental results demonstrate that remarkable torque ripple reduction, more than 30%, has been achieved. As a result, the proposed strategy is proved to be effective in reducing torque ripples for MC-based PMSM drives.