Phase Shift Technique to Improve Torque of Synchronous Reluctance Machines With Dual M-Phase Windings

This article proposes a torque improvement method for dual m -phase synchronous reluctance machines by phase shift technique. The emphasis is put on the relationship of d – q axis inductance harmonics and phase shifts. First, all feasible phase shifts for various slot/pole combinations are discussed in general. Second, the influences of phase shift on reluctance torque performance are investigated based on inductance analysis. It is founded that the first main torque harmonic can be eliminated when phase shift equals to π /2 m ( m is odd) and π / m ( m is even), respectively. This is the optimal phase shift covering all the m cases. Third, the optimal phase shift with torque improvement and ripple reduction is verified by the theoretical analysis and finite element method. Finally, the dual 3-phase 24-slot/10-pole synchronous reluctance machines with 30° and 60° phase shifts are fabricated. The experiments on the prototype machine are carried out for validation.