Research Of PMSM Sensorless Control System Based On New Observer

Permanent magnet synchronous motors(PMSM)are widely used in many industrial fields due to their high efficiency,small size and light weight.Mechanical sensors are typically added to obtain accurate position and velocity information,but the use of hardware sensors invisibly reduces reliability and durability.The permanent magnet synchronous motor control without position sensor has the characteristics of strong anti-disturbance capability and low cost.By extracting the current and voltage variables related to the speed,the rotor position and speed are estimated.This thesis studies the characteristics of PMSM,and analyzes the development status and classification of position sensorless.The pulse high frequency signal injection method can solve the problem that the position and speed estimation of the motor at zero speed and low speed are difficult to estimate.Sliding mode control can deal with the middle and high speed running and position estimation of the motor.These two methods are chosen as the research direction of this thesis.Based on the principle of high frequency pulse voltage injection method when the motor starts at zero speed,the high-frequency harmonic current component and the injection of the high-frequency harmonic current component obtained by the synchronous rotation q' axis are directly multiplied by the trigonometric sine function containing the input voltage frequency,and then extract the signal of the rotor position and the rotational speed,which reduces the use of the filter and optimizes the algorithm.At the same time,we analyze the magnetic saturation characteristics of the permanent magnet synchronous motor and improve the magnetic pole polarity determination of the rotor.The simulation model is built in the MATLAB/Simulink environment.The simulation analysis shows that the improved control method can effectively estimate the rotor position and velocity information at low speed and the system has good dynamic characteristics and robustness.The traditional sliding mode phase-locked loop can obtain the middle and high speed position signals of the motor rotor.This thesis takes the sliding mode observer of permanent magnet synchronous motor as the research object,first analyzes the basic principle of sliding mode variable structure control.The mathematical equation of the model observer uses the saturation function instead of the switching characteristic to weaken the buffeting of the sliding mode observer,and uses the Lyapunov stability theorem to determine the existence of the designed sliding mode observer and the asymptotic convergence of thecontrol system.The phase-locked loop performs phase tracking on the rotor position,which proves the correctness of the theoretical analysis.For sliding mode phase-locked loop adding low-pass filter to eliminate the high frequency interference caused by the phase lag problem,this thesis introduces second-order generalized integrator,studied its amplitude frequency characteristics,using the bandpass characteristics and low pass filtering effect,filtering the counter electromotive force,and will get the angular frequency of feedback to the new observer,as the phase lag of the resonant frequency to eliminate,to realize the adaptive function.Due to the shortcomings of the traditional PI controller in the complex nonlinear control system,a feedback linearization control method for permanent magnet synchronous motor is proposed.The PMSM control system is transformed into a first order current subsystem and a second order rotational speed subsystem.The sliding mode variable structure feedback linearization controller is designed to effectively overcome the influence of load disturbance on the system.MATLAB/Simulink model simulation shows that,in the middle and high speed segment of motor operation,this method improves the anti-perturbation of rotation speed change.It can accurately estimate the rotor speed and position,effectively suppress harmonic and noise,eliminate phase lag,and improve the dynamic and stability of the system.