Torque Performance Improving Strategy for DSEM Based on Online Self-Searching Six-State Advanced Angle Commutation

Advanced angle commutation (AAC) is an effective and easy-implemented approach to improve the torque performance for doubly salient electromagnetic machine (DSEM), in which six-state advanced angle commutation (SSAAC) is widely used due to the balance in torque improvement and commutation algorithm complexity. This article proposes a torque improving strategy for DSEM based on online self-searching SSAAC. First, the commutation process is researched in detail, and the quantitative expressions of the optimal advanced angles α and β are obtained according to the ideal DSEM model and commutation process. Then, for easier-implemented online searching, the reference current is selected as the feedback, in the advanced angles commutation region, the effects of the dual advanced angles α and β on output torque are analyzed, respectively. Based on this, the dual coupled advanced angles optimization is simplified into two independent single advanced angle optimizations. Afterwards, the golden section strategy is put forward to search the optimal α and β, respectively, online. With no requirement of any system parameters, the output torque performance is desired to be enhanced in terms of torque current ratio as well as torque ripple. The experimental results on a 12/8-pole DSEM prototype validate the correctness and feasibility of the proposed strategies under multiple operating conditions.