Maximum torque control of hybrid excitation synchronous machine drives based on field current self-optimizing method

This paper proposes a maximum torque control (MTC) strategy for hybrid excitation synchronous motor (HESM), which can achieve high-efficient controllability of air-gap flux. Due to the nonlinear relationship between field current and electromagnetic torque, it is significant to seek the optimal value of field current to obtain the maximum torque output. A field current self-optimization method based on variable step-size search theory, considering the voltage and current limit and 3-region division of the whole speed range, is presented. The flowchart of MTC according to the proposed strategy is constructed. By incorporating field current self-optimization method into traditional vector control, the coordinated control of armature current and field current is implemented, resulting in the enhancement of dynamic performance and expansion of high-speed operation range of the HESM. The simulation and analysis of the drive system with respect to a rotor magnet-shunting HESM is implemented, and the prototype HESM drive system is developed. The effectiveness of the proposed MTC strategy is verified by the simulation and experimental results.