Comparative Study of Performance for Different Winding Connections of Dual-channel Switched Reluctance Machine Using Frozen Permeability

Inductance characteristics play an important role in the output torque of the switched reluctance motor (SRM) whereas the windings connection form affects the mutual coupling between phases. According to the magnetic polarity models, dual-channel switched reluctance machine (DCSRM) with NNNSSSNNNSSS winding polarity is defined as DCSRMI, DCSRM with NSNSNSNSNSNS is defined as DCSRM2 and DCSRM with NNSSNNSSNNSS is defined as DCSRM3. Previous papers show that DCSRMs with different winding connections can offer different average torque, copper loss, iron loss and efficiency, but the work that different winding connections of DCSRMs running with channel fault is rarely carried out. This paper presents comparative studies of dynamic performance and magnetic characteristics of DCSRMs running with channel fault whereas only the winding connection type that differs. The frozen permeability method is adopted to compute static inductance and torque characteristics and to analyze the magnetic characteristics of the different winding connection models. The results show that the connection type of DCSRM3 can obviously enhance the average torque and minimize the torque ripple under the condition of channel fault. However the iron loss of DCSRM3 is highest among the three types under dual-channel excitation condition, which lowers the overall efficiency. By simulation analyses, a novel four-phase 16/12-poles fault-tolerant DCSRM called even-phase fault tolerance has been proposed. No matter in dual-channel excitation nor in single-channel excitation operation conditions, the performance of this even-phase DCSRM can be the best.