Common-Mode Voltage Minimization of Matrix Converter-Fed Permanent Magnet Synchronous Motor System with Evenly Distributed Virtual Rotation Vectors

The rotation vector of the matrix converter has the characteristic that the common mode voltage is zero, so the direct torque control (DTC) strategy using the rotation vector can effectively suppress the common mode voltage of the motor system. However, because the direction of the rotation vector is constantly changing and the distribution is extremely uneven, the existing DTC based on the rotation vector not only has a complicated switching table, but also increases the torque ripple and current harmonics. In this paper, a novel direct torque control strategy using virtual rotation vectors is proposed. The virtual rotation vector is synthesized by the rotation vector with identical rotating direction, and the duty cycle of the selected rotation vector is theoretically derived and calculated, leading to six evenly distributed virtual rotation vectors with fixed relative positions, and therefore a simple-form switching table can be easily constructed. The proposed control strategy is experimentally verified, and the results show that, compared with the traditional rotation vector-based DTC, the proposed strategy not only achieves zero common-mode voltage, but also significantly reduces torque ripple and current harmonics, improving the steady-state performance of the motor system.