Sensorless Direct Torque Control For Permanent Magnet Synchronous Motor

This paper firstly present the development and situation of some control schemes for Permanent Magnet Synchronous Motor (PMSM),then,it find that direct torque control(DTC) is play a important part in improving the program of PMSM and sensor-less technology. Therefore,this paper focuses on the direct torque control for PMSM,sensor-less technology and sliding mode control theory. Based on the scheme,the simulation model for PMSM DTC is set up using Matlab/Simulink.The main content of the study as follows:From the theory of space vector,the equations of flux,voltage and torque is induced,also we indicate that zero vector has an effect of reduce the torque ripple.The control modules of the system and way to achieve are discussed. A traditional permanent magnet synchronous motor with direct torque control system and simulation based on Matlab/simulink is set up.The simulation results show the feasibility of direct torque control theory.A PMSM DTC based on EKF is presented in this paper.EKF is based on (α-β)axis motor model consists of stator current,stator flux linkage,,angular speed & position of rotor and other motor parameters.EKF improves the accuracy of stator flux,and it is robust to parameters change and load disturbance.To overcome the defects of the use of machinery to speed sensor in the system,the control of reactive power model referencing adaptive system(MRAS) method is used to reach the simulation of PMSM DTC. Simulation results show an ideal control.Given the lack of PI regulator,sliding mode control theory is introduced to PMSM DTC,the general sliding mode control is applied to the permanent magnet synchronous motor with direct torque control system,and substitute PI adjustor of traditional regulation reached the desired control.Based on the study of theory, we design a hardware platform with the arrangement of DSP and PMSM DTC software. Through the analysis of theory,simulation and experiment,we get some useful experience and conclusion.All of this will be help in the further research.