Sensor Less Control System Of PMSM Based On Sliding Mode Algorithms

The Permanent Magnet Synchronous Motor(PMSM)has the advantages like small size,high power density,high efficiency and good speed control performance.These characteristics meet the requirements of motor for vehicles,which makes PMSM become the preferred driving motor for most electric vehicle enterprises.The PMSM is a complex electromechanical system which is multi-variable,strongly coupled and non-linear.The variations of parameters and external disturbances affects the performance of the control system during operation.The speed Sliding Mode Controller(SMC),which adopted in this paper,can effectively improve the robustness and anti-jamming ability of the control system.And the response speed is fast and the implementation is simple.At the same time,the traditional control systems mostly use accurate signals of position and speed.The traditional PMSM control system mostly uses resolver encoder or photoelectric encoder,which will increase the space occupied,the manufacturing and maintenance cost of the control system.To solve this problem,this paper adopts a sensor less control system,which can estimate position and speed information online by collecting current and voltage,thus eliminating position sensors.This dissertation analyses the structure characteristics of PMSM,establishes its mathematical model in synchronous rotating coordinate system,and expounds the realization methods of Vector Control and Maximum Torque Per Ampere.Because the discontinuity of the SMC leads to the problem of "chattering" in the control system.In order to solve the influence of "chattering" on the system,the speed SMC designed in this paper adopts a fast terminal sliding surface,which can effectively reduce chattering and guarantee the fast response.The tangent position estimation algorithm is affected by the system parameter disturbance.In order to reduce this influence,the position estimation of sensor less control system designed in this dissertation is based on sliding mode observer,which uses integral sliding mode surface and exponential reaching law to weaken the influence of chattering on the system.At the same time,the observer uses phase-locked loop algorithm to eliminate jitter and improve estimation accuracy.The simulation model of MATLAB is established to prove the feasibility of the algorithm.The control system of PMSM is designed base on the DSP28335.Some circuit principles of the control system are expounded,and the control flow of the software program of the controller is introduced.Finally,the validity of all the algorithms proposed in this paper is verified by experiments.