Research On Sliding Mode Control Technology In Permanent Magnet Synchronous Linear Motor

With the development of the electrical machine and its drive control technology, permanent magnet synchronous linear motor(PMSLM) with direct drive comes into being. Compared with the traditional rotating motor with ball screw, it changes the intermediate gearing into the direct drive load movement, avoiding the effects due to the mechanical transmission. As a result, it has some features such as high efficiency, high speed and high acceleration. However, as the linear motor itself has nonlinear factors such as parameters variation and load disturbance, it will have adverse effects on the performance of the servo system if not handled properly. Therefore, this article will apply the sliding-mode control to solve the problem of nonlinear factors of motor, and get the verification by experiment, eventually, reach the target of motor thrust smooth output and timely response of speed.Firstly, the article analyzes the structure characteristics and working principle of PMSLM, establishes the mathematical model in the synchronous rotating coordinate system by using coordinate transformation theory, and introduces the work principle of inverter and space voltage vector pulse width modulation technology(SVPWM).Secondly, the paper establishes the simulation model of servo control system of motor in SIMULINK simulation environment to carry out the experiment. On account of the defects of traditional velocity loop PI controller, the paper designs a sliding mode controller, which is used to replace the original one and carry out simulation experiment, based on the exponential approach law. Then, in view of the chattering problem in the sliding mode control, the paper introduces the integration switching surface and alteration index reaching law to design and improve the speeding sliding mode controller. According to the simulation results, it shows that the improved sliding mode controller not only enhances the anti-jamming ability of the servo control system, but also largely reduces the system chattering on the sliding mode switching surface.Finally, the paper introduces the design scheme of hardware and software of the permanent magnet synchronous linear motor servo control system. The hardware includes the system control circuit with STM32F407 as its core, the power-driven circuit with Mitsubishi Corporation’s IPM module as its core and the surrounding ancillary circuit. The software, based on the idea of layering and modularity, writes each function subroutines on the Keil5 platform in order to realize the servo control of the motor. Comparing the preliminary experimental results with that of the system simulation, the paper verifies the rationality and feasibility of this scheme when speed ring adopts the sliding mode controller, which will lay solid foundation for the follow-up research work including the further system optimization and control strategies improvement.