Research on Topology of Main Power Converter and Control Strategy for Loss-of-excitation Fault-tolerant DSEM

In order to improve the fault-tolerant operation ability of doubly salient electromagnetic machine (DSEM), the winding turns of DSEM has been redesigned. However, the increase of winding self-inductance causes the current to rise slowly during commutation, which affects the output torque. Therefore, the dynamic current response of the loss-of-excitation fault-tolerant DSEM based on the bridge converter and the H-bridge converter during commutation is analyzed, and the field-circuit co-simulation verification is carried out. Then, based on the above analysis, the half-cycle mode control strategy is reconsidered. This strategy fully utilizes the significantly increased reluctance torque derived from the fault-tolerant designed motor, and reduces the large torque ripple caused by the rising reluctance torque in double-beat mode, which is difficult to fully offset. Besides, this paper establishes the field-circuit co-simulation model to simulate and analyze the fault-tolerant DSEM electric operation based on different control strategies. Finally, the prototype is developed and verified experimentally. The results indicate that the half-cycle mode control strategy is worth reconsidering due to the significant increase in phase self-inductance of the fault-tolerant DSEM. This mode can effectively suppress the torque ripple of the fault-tolerant DSEM, and there is no need to change the control strategy for normal and loss of excitation operation, reducing the difficulty of control.