Study On The Technology Of PMSM Sensorless Control System

Permanent magnet synchronous motor (PMSM) has the technical features ofhigh efficiency and high power factor. It will be the development direction of thefuture high efficiency drive system.the magnetic circuit of permanent magnet motor iscomplex and multiple. Because of its well performance,simplicity and reliability,thevector control technology has been widely used in a variety of the high-performanceAC motor control.The high performance sensor-less control of PMSM also attractedwidespread attention. Although several sensor-less control technologies are currentlyimplemented, each method has its own adaptation of the speed range, none of themcan achieve the full speed range. Aiming at this problem, this thesis proposed acomplex control method to achieve the full speed range control. The method wassimulated and the result showed that the estimation accuracy was improved, whichwas good. The paper is composed of several aspects as follows:On the basis of the mathematical model of the PMSM,the commonly usedcontrol methods were analyzed.Established the double-loop of current and speedPMSM vector control system where id=0. The method was adopted to establish themodel of PMSM vector control system, which was simulated to verify its correctness.The traditional Extended Kalman filter methods were introduced to establish aEKF-based sensor-less PMSM control system, which was simulated to prove thefeasibility of the method.For the EKF method’s bad estimation accuracy at low speed,built the mathematicmodel of IPMSM under high frequency excitation. The principle of estimating rotorposition and speed with high frequency voltage signal injection was elaborated. Thesimulation model of PMSM sensor-less control system was set up to do simulationresearch in Matlab/Simulink. The simulation results verified the accuracy of thealgorithm. On the basis of the two methods above, a weighted algorithm was proposedto achieve the control at full speed range. This method can effectively achieve thesmooth switching between low speed and high speed,The method was verifiedthrough the simulation.Before starting the PMSM,the initial rotor position should be detected, this papercombine the high frequency voltage injection method and the saturation of the statorcore to accurately estimate rotor position and to determine the initial polarity of thepermanent magnet. The method was simulated with the Ansoft software,and the results accorded with the theoretical analysis well. Based on this, the experiment ofPMSM initial position detection was carried, and the results showed that this methodcan simply and effectively detect the initial position and identify the polarity of therotor.