Common-Mode Voltage Elimination of Dual Three-Phase Motor with Different Angular Displacements

Pulsewidth modulation inverter driven motor will suffer from common-mode (CM) voltage, which will not only cause electromagnetic interference to the system, but also cause CM leakage current to damage the motor bearings. Driven by a two-level voltage-source inverter), the dual three-phase motor (DTPM) system with even numbers of phase-legs provides an opportunity to cancel the CM voltage actively. This article proposes a CMV suppression method that can be applied to DTPMs with arbitrary angle displacement (AD). Based on the principle of space vector modulation, this method uses four effective zero common-mode voltage vectors to synthesize the reference voltage, and uses virtual-voltage vectors (VVs) to simplify the synthesis process. While suppressing the CMV, the vector assignment also takes into account the harmonic suppression of the system. The suggested method can achieve the elimination of CMV for DTPM with arbitrary AD, and can improve the maximum modulation ratio of the system. The maximum modulation ratios for 30° and 60° are 1.035 and 1.154, respectively. Therefore, the proposed method has certain practicality. Finally, the CM voltage suppression method is verified on a 12-slot/10-pole permanent magnet synchronous motor with different angle displacements (ADs).