Online Adaptive Maximum Torque Per Ampere Control for Doubly Salient Electromagnetic Machine

Advanced angle control (AAC) is an effective approach to improve the output torque performance of doubly salient electromagnetic machine (DSEM). But the optimal advanced angle varies with multiple time-changing parameters, such as motor speed, load torque, phase resistances,
etc
., bringing difficulty to obtain the online optimal AAC. To deal with this problem, this article proposes an online adaptive maximum torque per ampere control strategy for DSEM. The commutation process is analyzed in detail, and the quantitative expression of optimal angle is obtained. Then, based on the convex characteristic between the advanced angle and DC bus current, an online gradient searching method for the optimal advanced angle is put forward by utilizing the DC bus current as the feedback, no motor parameters are pre-required. Afterwards, based on the analysis of the tradeoff between the searching accuracy and speed, the designing rules for control parameters are obtained. What's more, the feature of DC bus current ripple is explored, and an average DC bus current sampling method is put forward for easier implementation of the proposed searching method. Finally, the experiments on a 12/8-pole DSEM verify the correctness and feasibility of the proposed strategy under multiple operating conditions.