The Research Of Position Estimation For Permanent Magnet Synchronous Linear Motor Based On Sensorless Control

The control strategy of "roller screw and rotary motor" is widely used to produce linear motion in the field of industrial control which the control precision will be decreased due to the transfer construct. While the permanent magnet synchronous linear motor (PMSLM) is gradually used in high speed and precision machine tools for its high thrust、high acceleration and high position accuracy. The key to realize the precise position control of permanent magnet synchronous linear motor is whether the real time position of PMSLM can be observed precisely.In the conventional PMSLM drive systems, position control is achieved through high precision position sensors such as grating sensor, magnetic grid sensor and Hall-effect sensor. However, a position sensor presents some disadvantages such as high requirement of working environments adding the cost and reliability、increasing the complexity, weight and so on. In view of the disadvantage of position sensor in PMSLM, the control strategy of sensorless is used in permanent magnet synchronous linear motor to overcome above shortcomings and improve the system reliability and dynamic performance in this paper.At the beginning, the working principle of PMSLM is analyzed. The equation of permanent magnet synchronous linear motor is deduced based on ap and dq coordinate system. For the disadvantage of position sensor, the sensorless control technology is proposed to estimate the real time position of PMSLM. On the other hand, the way to realize the permanent magnet synchronous linear motor started without position sensor is discussed.Secondly, the sensorless control of PMSLM is researched based on the theory of nonlinear status estimation. According to the working principle of kalman filter, the extend kalman filter algorithm (EKF) is proposed. Then, the recursion formula of EKF algorithm is deduced. At the same time, the state mathematical equation of PMSLM is established based on EKF algorithm. In the end, the model of PMSLM control system based on EKF in Simulink simulation environment is developed. The simulation result shows that EKF is effective to estimate position and speed in a wide position range. The dynamic responsibility of the PMSLM without position sensor based on EKF is fast.At last, we designed a hardware experiment platform to test the precision of the EKF estimator based on the real time simulation machine AD5435. From the result of experiment, the position of PMSLM can be estimated well by EKF algorithm. It has a better tracking performance. Research on permanent magnet synchronous linear motor based on EKF algorithm has an important significance in the field of high speed and precision control system.