Position Sensorless Control Of Magnetic Levitation System Based On Lock-in Amplifier Technology

The magnetic levitation technology has been extensively studied for its advantages such as non-contact, long life, low power consumption and no friction. For the purpose of achieving the controllable position of the magnetic levitation system, position sensors installed are usually used to transmit the position information of suspended solids. However, the installation of position sensors can result in bigger mechanical size, complexity of circuit hardware and increased costs of the system. To overcome these drawbacks, researchers begin to study position sensorless control. Therefore, the technology of using lock-in amplifier to control the position sensorless magnetic levitation system is proposed in this paper. The main achievements are summarized as follows.First, it proposes a controllable mode in which for position sensorless magnetic levitation systems based on lock-in amplifier technology. According to this mode, this paper analyzes the working mechanism of the position sensorless magnetic levitation system, introduces the structure and work process of the position sensorless magnetic levitation system, and deduces the method of gap length measurement used herein according to the principles of location estimation method.Then, it completes optimal design for the operating point parameters of position sensorless magnetic levitation system. By analyzing the association and conflict between various parameters, compromise values of individual parameters are selected to meet the optimal performance requirement of the system.Further, this article studies the control of magnetic levitation system. On the basis of the mathematical model of magnetic levitation system, the PID controller and Back-stepping controller are designed. To illustrate the effectiveness of the proposed technology, the simulation of the system is conducted using the Simulink tool in Matlab. The simulation results show that the control for position sensorless magnetic levitation systems based on lock-in amplifier technology in this paper is feasible.Finally, this paper completes the experimental verification of position sensorless magnetic levitation system. The hardware circuit based on XE164 FN for position sensorless magnetic levitation system and software are designed. And this paper conducts the experimental study. Experimental results show that the feasible and effectiveness of the control for position sensorless magnetic levitation systems based on lock-in amplifier technology in this paper.