Control of Thrust and Attractive Force of Linear Induction Motor Driven by Power Source with Frequency Component Synchronous with the Motor Speed

Linear Induction Motors (LIMs) have many applications. The maglev transportation system is the most popular application. We have developed a maglev system using a LIM without the levitation system. The attractive force of the LIM can be used for the levitation control. In this system, we have proposed the control method of the thrust force and attractive force of the LIM driven by a power source with a frequency component synchronous with the motor speed. The slip of the frequency component synchronous with the motor speed is zero. This frequency component can only generate the attractive force. Therefore, this frequency component is able to adjust the attractive force for the levitation without the influence on the thrust force control because the thrust force is always zero. It is possible to apply the conventional vector control for the thrust force control of LIM. The controller becomes simple. In this paper, we present the controller that we designed for the proposed maglev system. The experimental results show the thrust and attractive force can be controlled by the proposed control method.