Reduction of Common-Mode Voltage in Five-Phase Induction Motor Drives Using Predictive Control Techniques

The common-mode voltage (CMV) is known to be a source of electromagnetic interference, and it is potentially dangerous for the machine windings´ insulation and bearings. CMV has been analyzed for three-phase machines supplied by voltage-source inverters, showing that modified pulsewidth modulation and model predictive control (MPC) techniques can significantly reduce the CMV at the expense of increased current distortion. This paper analyzes the CMV for five-phase drives and proposes a modified MPC strategy that accounts for the CMV reduction. The MPC can adjust the weights of the cost function to find a good balance between CMV reduction and low current distortion. The MPC strategy is experimentally tested showing how the CMV can be effectively reduced, thus improving the multiphase drive performance.