Optimization and Performance Improvement of a Hybrid Excitation Synchronous Machine With Modular Magnetic-Shunting Rotor

Hybrid excitation synchronous machines (HESMs) are regarded as special permanent magnet synchronous machines (PMSMs), in which flux linkage, inductances, and characteristic current change with field current. The machine topology, optimized structure design, and modular fabrication method of an HESM with magnetic-shunting rotor are presented in this paper. To solve the thermal problems, an optimized cooling system considering the rotor losses is proposed. Then, the feature of adjustable d-axis inductance and flux linkage are theoretically analyzed and calculated. As a result, the characteristic current changes with the field current, which is significant to the constant power range. The adjustable d-axis inductance, flux linkage, and characteristic current are validated by finite-element analysis results. According to the feature of adjustable characteristic current, an optimized control strategy is proposed to improve the output power capacity of the HESM with modular magnetic-shunting rotor in the whole speed range by taking full advantage of the adjustable characteristic current feature, in which the characteristic current is adjusted close to the rated current at high speed. To validate the feasibility and superiority of the optimized design and control methods, a 100-kW HESM with modular magnetic-shunting rotor prototype is designed, manufactured, and tested.