Direct Torque Control of Five-Phase Induction Motor With Common-Mode Voltage and Current Harmonics Reduction

This paper proposes two direct torque control (DTC) strategies to reduce the common-mode voltage (CMV) in the fivephase induction motor driven by three-level five-phase inverter. In each technique, 31 voltage vectors consisting of 30 nonzero voltage vectors, and a zero voltage vector are selected out of available 243 voltage vectors. The selection of these voltage vectors are based on their capabilities of reducing the CMV, eliminating the x-y stator flux and maintaining the torque ripple under control. The ten large, ten small, and a zero voltage vector are same in both schemes, however only difference in designing the control strategy for the two schemes is the utilization of different ten medium voltage vectors. First proposal (DTC-I) reduces the CMV to 3V
_dc
/10 and second proposal (DTC-II) reduces to V
_dc
/10. These schemes are compared with DTC technique of five-phase induction motor fed by two-level five-phase inverter in order to judge the capabilities of proposed schemes in context of reducing the CMV. The simulation and experimental results validate the proposed DTC techniques.