Research On Dynamic Stability Of ALA Rotor Motor

Axially-laminated anisotropic (ALA) rotor reluctance synchronous motor (RSM) is one of the solid candidate for the advanced high-performance AC variable-speed drives. Due to the novel rotor configuration, this motor can be equipped with the highest saliency ratio, which leads to high torque density, high efficiency, high power factor,fast response, low torque pulsation, low rotor loss, high reliability and simple control strategy compared to all other traditional motors, and provides the motor with potential and wide applications in the near future. Based on the wide investigation, the background of ALA rotor motor is highlighted first. Consequently, a comprehensive introduction to principle, structure, electromagnetic relationship and mathematical model is made. In order to eliminate the oscillation and asynchronous operation caused by an inverter supply, the concept of novel hybrid ALA rotor motor, having a permanent-magnet part and an ALA part mounted on the same shaft, is presented. A comprehensive analysis on the principle, structure,parameter evaluation, steady-state performance and design optimization is made. The contrastive startup experiments on the novel motor, fed by the inverter and the variable-frequency synchronous generator set respectively, are implemented. The original design purpose is verified since the startup performance of hybrid ALA rotor motor is enhanced remarkably. With the aid of permanent-magnet synchronous torque, the motor can run stably at rated speed, and presents prompt startup capability as well. After a comprehensive review on startup behaviors of various synchronous machines, a novel method is proposed to improve the startup performance of ALA rotor motor much applicably, i.e. to add a mechanical damper on the shaft, as done in the stepping motor. The original intention is on the basis of the theoretical analysis on the damping characteristic of ALA rotor motor. The experiments on three different structural propotypes show that the mounted damper provides an effective solution to ensure the stability of ALA rotor motor in open-loop operation. Besides, the feasibility of closed-loop operation of ALA rotor motor is investigated. The direct torque control (DTC) strategy is applied to the DSP-based control system and the relevant configurations on hardware as well as software are implemented. The experimental investigation reveals that the closed-loop operation of ALA rotor motor is not only feasible, but also a significant approach to improve the stability. At the end of the thesis, some suggestions aimed to future work are proposed.