Simplified Modulation Scheme for Open-End Winding PMSM System With Common DC Bus Under Open-Phase Fault Based on Circulating Current Suppression

This letter proposes a simplified modulation strategy for the open-end winding permanent-magnet synchronous motor (OW-PMSM) system with common dc bus under the open-phase fault condition, with the suppression of the circulating current. Based on the analysis of the voltage distribution of the OW-PMSM under the open-phase fault, a phase-shifted stationary coordinate system is proposed and applied to synthesize the reference voltage. In the proposed modulation process, the duration time of the two selected orthogonal voltage vectors is directly obtained and both sector identification and calculation of trigonometric function can be avoided. Furthermore, the arrangement of switching signals is achieved universally according to the switching states of the selected voltage vectors. Thus, the proposed modulation scheme can be greatly simplified, compared with the conventional strategies. Moreover, the current controller with low bandwidth is applied to suppress the circulating current, considering its effect on the currents in the synchronous rotating coordinate system. The performance of the proposed scheme is validated experimentally in an OW-PMSM system with a common dc bus under the open-phase fault.