High Grade Control Of Linear Induction Motor Drives

Abstract

Linear induction machines (LIM) have been widely utilized in military, transportation, aerospace due to the impressive advantages such as simple configuration, easy maintenance and high acceleration/deceleration. However, the existence of trailing eddy current effect and magnetic asymmetry effect undermines the expected functionality of vector control even though LIM inherent similarities from its rotary counterpart. As a result, it has been a focal research area to either improve the performance of vector control for LIM or develop a new high grade control strategy. Therefore, the in-depth knowledge of electromagnetic behavior of LIM is necessary. From both finite element analysis (FEA) and experiment, it is verified that the two open ends in the primary of LIM results in the magnetic asymmetry effects. Furthermore, both of the trailing eddy current effects and magnetic asymmetry effects cause non-sinusoidal magneto-motive force (MMF). This undermines the basic assumption of vector control that the fundamental MMF should be sinusoidal. Moreover, FEA is a good tool for numerical-based analysis of electrical machines. However, the computational effort is extremely intensive. Therefore, the field reconstruction method (FRM) for LIM is proposed in this dissertation. FRM significantly reduces the computational time, but supplies steady state calculation in good accuracy. This dissertation also proposes a maximum force/ampere control, which has impressive advantages such as simple implementation, easy controllability, and maximum energy conversion ratio. The maximum force/ampere control is validated by both simulation results and experimental verification. The contribution of this dissertation can be summarized as follows: 1. Systematic exploration of electromagnetic behavior of LIM; 2. Development of field reconstruction method for LIM; 3. Invention and implementation of maximum force/ampere control.