Control of Dual Three-Phase Permanent Magnet Synchronous Machine Based on Five-Leg Inverter

This paper proposes a current control of dual three-phase permanent magnet synchronous machine (PMSM) based on 5-leg inverter. The 5-leg inverter can be utilized to drive dual three-phase PMSM with full torque at slow speed when the conventional dual three-phase voltage source inverter(VSI) has a faulty inverter-leg. It can also be used deliberately in the electrical vehicle application for its reduced size and cost due to reduced switches compared with the conventional dual three-phase VSI, which is a six-leg inverter. Usually, the common leg in the five-leg inverter may have severe current stress. By dedicated selection of which two phases as a pair to share the common leg, its current rating is approximately half of current rating of other legs. Meanwhile, the 5-leg inverter can fully fulfill the vector space decomposition control for dual three-phase PMSM, which has the same dynamical performance as the conventional dual three-phase VSI. However, due to the asymmetry of five-leg inverter non-linearity, the currents of dual three-phase PMSM are unbalanced. To mitigate this issue, the 5-leg inverter non-linearity compensation is also introduced and investigated in this paper, whose effectiveness are verified by comparative experiments on a prototype dual three-phase PMSM.