Research And Application Of Sliding Mode Control For Permanent Magnet Synchronous Motor Servo System

The permanent magnet synchronous motor(PMSM) is widely used in servo system such as robot, high precision computer numerical control machine tool system, because it has a lot of advantages, such as high efficiency, small size, large torque output, convenient to control etc. However, PMSM is vulnerable of internal parameter variations and external disturbance. The conventional vector control and direct torque control algorithm are usually used in PMSM servo system, but they are difficult to meet the requirements of high performance servo system control. Due to the robustness and disturbance attenuation of the sliding mode control, it has got the attention of many scholars and is successfully used in PMSM servo system, but it will bring chattering to the system.An adaptive sliding mode controller(SMC) with load torque compensation and an adaptive SMC based on MTPA principle are designed in this paper in order to intensify the system disturbance attenuation and reduce chattering at the same time. The control effect and comparison research of the two methods are validated from the Matlab simulation results. The main content of this paper is as follows:First, the research status and development trend of the PMSM servo system at home and abroad are introduced including the servo drive system and control strategy.Second, the theory of the sliding mode control is expounded. The chattering problem is introduced, and the measures to reduce the chattering effectively are proposed.Third, the adaptive SMC based on di0?? principle is designed. So as to further impair the chattering of SMC, a load torque observer is presented to observe the changes of the load torque, and the disturbance torque compensation current is added to the controller. The current regulator is designed, and the system stability is analyzed. Then, the Matlab/Simulink model is built. Perfect tracking performance, anti-interference ability and robustness have been obtained, and the chattering is also weakened.Fourth, the fast terminal sliding mode surface is used to replace the linear sliding mode surface. A new adaptive sliding mode reaching law is designed to enhance the anti-interference ability of the system and to impair the chattering. The polynomial curve fitting MTPA principle is used to get the d-axis and q-axis currents to improve the engineering practicability. Then, the Matlab/Simulink model is built, the simulation results show that the presented controller have a good control performance. Moreover, better current efficiency, output torque and response speed are achieved from MTPA control.At last, an orthogonal coordinate robot control system is designed. It is made up of hardware design, software design and trajectory planning. From the trajectory planning results we know, the PMSM servo system is well applied to the orthogonal coordinate robot control system and have a good engineering practicability.The simulation and experiments results show that the sliding mode controller of PMSM servo system and the orthogonal coordinate robot control system designed in this paper have a good control effect and good application prospect.