Analysis and Optimization of Rotor Salient Pole Reluctance Considering Multi–Modulation Orders

With the aid of general airgap field modulation theory, the torque production mechanism of flux-reversal permanent magnet (FRPM) machines is revealed, and it finds that multimodulation orders of the rotor salient pole reluctance, i.e., dc modulation, first order modulation and second order modulation, have effects on FRPM machine performances, regardless of pole pair combinations. Therefore, analysis and optimization of rotor salient pole reluctance can be further improved by considering these three modulation orders, and the 12/10, 12/14, and 12/16 pole FRPM machines are taken as optimization examples together with proving their identical optimum rotor configuration. Sensitivity analysis is applied to increase the machine optimization efficiency. By comparing symmetric and asymmetric rotor configurations’ differences in contributions to machine performance considering effects of multimodulation orders, a combined optimum rotor configuration is proposed. Both finite-element analysis and experiments verify the effectiveness of theoretical analysis.