Torque Ripple and Harmonic Current Reduction in a Three-Level Inverter-Fed Direct-Torque-Controlled Five-Phase Induction Motor

Abstract

In a switching-table-based direct torque control method (ST-DTC), the torque ripple reduces with increasing number of levels of the torque comparator. The number of levels is decided by the availability of the number of voltage vectors according to the topology of the inverter. This paper proposes the seven-level torque comparator to reduce the torque ripple in the DTC-controlled five-phase induction motor fed by the three-level five-phase inverter. In the five-phase induction motor, an elimination of x − y stator flux is inevitable otherwise the stator phase current will be distorted. In order to eliminate the x − y stator flux, the virtual voltage vectors are formed. Experimental results are presented to validate the proposed DTC method.