Research Of Hybrid-levitation Control System Based On The Test Platform Of Linear Induction Motor

Compared with traditional AC motor drives, Single-sided linear motor(SLIM) as electrical drives has the advantage of little section of underground tunnel, strong climbing ability, low noise, etc, but low efficiency and low power factor, which is the most concerning problem. So it is significant in test of the dynamic performance of thrust and vertical force of LIM. This paper presents the method of measuring thrust and vertical force of LIM based on maglev principle. It applies the principle of maglev to fix air gap between its primary and secondary coil. It is known that the acceleration of LIM can be measured by use of position sensors installed on it, and then the thrust performance of LIM under decided air gap can be obtained. According to the current of electromagnet controlled the LIM to suspend and the preset air gap, the electromagnetic force of controlled electromagnet can be calculated. And vertical force of measured LIM can be obtained after gravity is been subtracted.In this paper, maglev principle and control method is studied; the part of the maglev is used the way of hybrid electromagnet and permanent magnetism, and the dynamic model of hybrid-levitation system is established. Also, the corresponding linear model of the hybrid-levitation system is established according to two method linearization, that is, one is base on the balance point, the other is based on feedback linearization method.In view of facts above, the control methods are put forward based on feedback linearization method and PID control method. The parameters are also discussed according Routh criterion. Based on MATLAB/Simulike, the simulink model of the hybrid-levitation system was derived in order to prove the feasibility of the control methods. In another way, a new controller is designed based on Sliding Mode Variable Structure Control and feedback linearization method. The existence conditon of slide mode control was given. By simulation, the validity of controller for the hybrid-levitation system is tested.After the feasibility of the control methods are proved, the hardware and software of the suspend system is designed. Finally, a series of experimental study are done and the stability is confirmed.