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.

I. Introduction

In the 1990s, Professor T. A. Lipo proposed a novel doubly salient permanent magnetic motor (DSPM), and carried out preliminary theoretical analysis and experimental research [1]. The doubly salient electro-magnetic motor (DSEM) is developed on the basis of DSPM. It is easy to realize the flux weakening control in the electric process and the voltage regulation control in the power generation process by replacing the DSPM stator magnet with the excitation winding [2–4]. Therefore, DSEM has a great application potential prospect in aerospace, new energy power generation and other fields. However, these fields require high reliability of motors. While fault-tolerant motor technology can effectively improve the reliability of motor systems, which has received increasing attention from scholars in recent years [5].