Research On Buffeting Problem Of Control System Of Permanent Magnet Synchronous Motor Basing On Sliding Mode Variable Structure

PMSM(Permanent Magnet Synchronous Motor)is widely used in industrial production and life because of its structural characteristics,high efficiency,high power factor,high precision control performance and excellent torque stability.However,because PMSM is a very representative multi-input and output nonlinear system,it is easily affected by external environment disturbances such as external load disturbance,internal parameter perturbation and temperature abrupt changing in practical applications.Sliding mode control,due to its unique control mode,has been widely used in the research of enhanced motor robustness control for load disturbance,parameter temperature drift and rapid response.However,it is precisely because of the structural characteristics of the sliding mode that it provides excellent anti-interference control performance,but also brings the chattering problem to the system,so that it encounters great resistance in the widespread use in actual production.The chattering problem generated by the PMSM control system based on sliding mode structure is analyzed and explored,mainly including the following contents.(1)Firstly,the control system model of PMSM based on sliding mode structure is built,and the exponential approach law in sliding mode structure is studied.It is concluded that the rate and method of sliding mode chattering and approaching law are inextricably linked.Therefore,based on this,we design a new type of upper and lower bounds of preset load torque based on sliding mode variable structure variable index.Approaching law,which closely relates the change of state variables to velocity error,improves the sliding mode control rate in real time according to the distance of the state variable from the sliding surface to accelerate the approach rate,at the same time suppressing the chattering of sliding mode inherent.Finally,the design scheme of sliding mode governor based on improved approach law is given,and the sliding mode governing system of PMSM based on the above new approach law is built.(2)In-depth exploration of the negative effects of disturbance on the control performance of the system,an extended sliding mode disturbance observer is proposed which uses the disturbance amount as the state input to achieve the control effect.Moreover,the disturbance observer can not only accurately estimate the external load interference and internal parameter disturbance,but also has the first-order filtering effect to greatly reduce the sliding mode chattering.In order to solve the problems of system variable disturbance and external disturbance,an anti-disturbance composite control method is presented.The scheme combines the given disturbance observer with the sliding mode governor to treat the estimated disturbance amount as the input of the sliding mode speed regulator to enhance the anti-jamming level of the PMSM speed control system.(3)A super-helical control algorithm is studied.This algorithm uses series high-order sliding mode to ensure the continuity of control output and solve the chattering problem caused by high-frequency switching in sliding mode control.The important feature of super-helix algorithm is that it only needs knowing the information of the sliding modulus without the information of the first derivative,the super-spiral algorithm can reduce the chattering generated by the sliding mode structure with the relevant dimension of 1,and at the same time has the quick response and fault tolerance of the ordinary sliding mode.(4)For the super-helical control algorithm,it excessively depends on the upper bound of the boundary function,which is difficult to obtain in practice.Because fuzzy control do not depend on mathematical models,it relies on the structural characteristics of fuzzy rules,which is robust and greatly weakens external parameter interference and internal parameter perturbation,especially for the control of nonlinear systems.Here we introduce the fuzzy rule that estimates the upper bound of the boundary function.So we designed a fuzzy super-slip SMO(sliding mode observer).(5)Finally,rebuild PMSM control system model.In this model,we add the improved composite sliding mode speed controller,expanding the sliding mode disturbance observer and the fuzzy super-slip sliding mode observer,and build them in Matlab.Comparing the simulation results of the modified sliding mode variable structure PMSM control system with the simulation results of the traditional sliding mode PMSM control system,and proves the rationality and effectiveness of the proposed control strategy.