A Torque Impulse Balance Control for Multi-Tooth Fault Tolerant Switched-Flux Machines under Open-Circuit Fault

The multi-tooth fault tolerant switched-flux machines (MTFTSFM) providing both excellent fault tolerant capability and relatively high torque density are good choices for high reliability applications. A rapid control of the electromagnetic torque under open-circuit fault can always be achieved by the direct torque control with voltage vector reconstruction (RDTC); however, with respect to the rotor speed, its dynamic performance is still impacted by the proportion-integration (PI) parameters. Therefore, a torque impulse balance control (TIBC) is investigated in this paper for the MTFTSFM under open-circuit fault to obtain excellent dynamic performance of the rotor speed. During the dynamic state, the electromagnetic torque and the speed can converge at the same time after only one adjustment of the speed by using the optimized voltage vector sequence based on torque impulse balance, thus, achieving the best possible dynamic process for the speed. The TIBC method is carried out on an MTFTSPM machine system, and the correctness and effectiveness are verified.

Synchronous Motor Pull-in Process Analysis

In this paper, simple approach to analyzing the starting procedure of synchronous motors (SMs) is presented with an emphasis on the pull-in process. Instead of the classical, mostly intuitive pulling-repelling torque approach, an analytical method based on the motor mechanical part swing equation is employed. Factors affecting starting and pull-in processes are clearly indicated and torque impulse balance leading to a pull into step is revealed. It is shown that if the motor fails to pull into step within a single oscillation, it can still be synchronized during one of the succeeding acceleration periods. The crucial role of the excitation winding energizing instant is demonstrated as well. Moreover, the revealed similarity between the SM and phase locked loop (PLL) operations, leads to the conclusion that the algorithms use for analyzing the operation of one may be employed for investigating the other. Experimental results are given to demonstrate the different scenarios, mentioned in the manuscript.