Reduction of Common- Mode Voltage in Matrix Convert- Fed Permanent Magnet Synchronous Motor System with Rotating Vectors

A novel direct torque control (DTC) strategy is proposed to reduce common- mode voltage in matrix converter (MC)- fed permanent magnet synchronous motor (PMSM) system, by way of replacing some of the active vectors in the traditional DTC switching table with rotating vectors. According to the variation of the direction distribution of the rotating vector with the input voltage phase angle, the range of input voltage phase angle is divided into two intervals. In one interval, some of the active vectors are replaced by rotating vectors; in the other, all vectors used are rotating vectors. The novel DTC switching table is obtained accordingly. Experimental study verified the effectiveness of the new control strategy. The results show that more than 60% of the common-mode voltage can be suppressed, while the waveform quality of torque and current can be reserved.