Research On PMSM Sensorless Control Method Based On Improved Extended State Observer

Permanent Magnet Synchronous Motor(PMSM)has the characteristics of small size,high efficiency and large starting torque,and is widely used in engineering.When the field-oriented vector control algorithm is used,to realize the decoupling control of the magnetic field and torque,it is necessary to obtain accurate rotor position information to complete the closed-loop control.Sliding mode control is one of the most widely used sensorless control algorithms,which has strong robustness.However,there is a phenomenon of sliding mode chattering,which affects the observation accuracy of rotor position and speed information.Disturbances such as sudden change in torque and perturbation of motor parameters have a great impact on the motor speed regulation performance.The current sliding mode chattering suppression technology and the PMSM anti-disturbance control technology are imperfected,hence need to be studied and improved.The main research work and results of this paper are as follows:(1)A sensorless sliding mode observer control algorithm based on improved exponential approach law is proposed.The isokinetic approach law used by the traditional sliding mode observer has problems such as long convergence time,high speed when reaching the sliding mode surface for the first time,and inability to adjust the sliding mode gain.Hence,an improved approach law based on the traditional exponential function approach law is proposed,and the measured system state variables are introduced to improve the reaching motion.The sliding mode gain can be adaptively adjusted with the measured state variables.The sliding mode chattering phenomenon is effectively weakened.Combined with improved sliding mode observer and phase-locked loop technology,a PMSM rotor position observation system is established to achieve accurate rotor position estimation.(2)An Active Disturbance Rejection Control(ADRC)based on improved extended state observer is proposed.The nonlinear function fal(x,α,δ)commonly used in traditional ADRC is not differentiable at the piecewise point,which leads to observation accuracy decreasing of the extended state observer.Therefore,an improved nonlinear function ifal(x,α,δ)is proposed,which adopts a fitting interpolation method on the traditional nonlinear function.The fitting method is a linear combination of polynomial and tangent function.The improved nonlinear function is continuously differentiable at the switching point.A PMSM speed loop controller based on the improved ADRC is designed by applying the novel function to the extended state observer,which effectively enhances the system response to disturbances such as load torque mutation and motor parameter perturbation resistance.(3)By combining the improved sliding mode observer with the improved ADRC,the improved sliding mode observer can achieve high-precision estimation of the rotor position,and the improved active disturbance rejection control can improve the system response to sudden load torque change,motor parameter perturbation and other disturbance.The new method takes advantages from both sides and improves robustness for position sensorless vector controlled PMSM.(4)The novel PMSM control algorithm model based on the improved sliding mode observer and the improved ADRC is built in the MATLAB/Simulink software platform.The simulation results show that the algorithm can effectively improve the PMSM performance.A PMSM experimental platform based on TMS320F28335 is built,and the algorithm is tested on the platform.The effectiveness of the algorithm is verified by the experimental results.