Research On Permanent Magnet Synchronous Motor Control Based On Sliding Mode Variable Structure

The speed control system of a robotic arm is a system that can precisely control the speed and accomplish tasks that are difficult for humans.It plays an important role in modern industry.PMSM is one of the common types of motors,known for its simple structure,convenient use,and high reliability.It finds extensive application in the speed control systems of robotic arms,enabling improved dynamic response performance and more accurate speed control.However,when facing more complex speed operating conditions,traditional proportional-integral control exhibits issues such as slow response time,high overshoot,and poor disturbance rejection in the speed control system.Improving these problems has become a hot topic of research.This article mainly focuses on the speed controller and load disturbance rejection in the control system of Permanent Magnet Synchronous Motors to enhance the response time of the speed control loop and improve the disturbance rejection capability of the speed control system.Firstly,to address the issue of slow response time in the speed controller of Permanent Magnet Synchronous Motors within complex control systems,an improved sliding mode control approach is proposed to enhance the performance of the control system.The design of sliding mode control includes the selection of the sliding surface and the design of the reaching rate.To account for the influence of the actual model’s viscous friction coefficient,an integral sliding mode approach is employed as the method for selecting the sliding surface.To further improve the reaching rate of the control system towards the sliding surface,an improved exponential reaching rate method is proposed.A simulation model is constructed in software to compare the performance in terms of speed response time with the traditional sliding mode control method,and the experimental results demonstrate better effectiveness with the proposed approach.Secondly,to address the issues of long response time and excessive speed fluctuations in Permanent Magnet Synchronous Motors under load disturbances,a disturbance observer approach is employed to enhance the disturbance rejection capability of the speed control system.In order to mitigate the effects of load disturbances,a sliding mode disturbance observer method is proposed based on the sliding mode concept.Additionally,a continuous function is utilized to replace the sign function of the observer to minimize speed fluctuations.To further improve speed stability,an extended observer design method is employed.The proposed disturbance observer is combined with the improved sliding mode control to form a composite control system.The disturbance observer estimates the applied load and compensates for the estimated disturbance in real-time by modifying the output current of the speed controller.Experimental results demonstrate that this composite control system can mitigate the impact of load disturbances.Lastly,to validate the effectiveness of the improved sliding mode control method and the composite control system algorithm proposed in this paper,a semi-physical simulation platform is built for a servo control system.The quick response time of the motor speed and the disturbance rejection capability against load disturbances are separately verified.In comparison experiments with traditional sliding mode control methods,the results show that the improved sliding mode control method achieves faster response time when the speed reaches a steady state.In the load disturbance experiments,different loads are applied to the motor to verify the disturbance rejection capability of the Permanent Magnet Synchronous Motors under the composite control system.The experimental results demonstrate that both observers can effectively suppress the problem of significant speed fluctuations under sudden load changes.