The Simulation Research Of Direct Torque Control In Permanent Magnet Synchronous Motor

In the field of AC machines control, direct torque control, by virtue of novel idea, simplecontrol structure, algorithm easy to implement and fast torque response, plays an importantrole in the field of motion control. Permanent-magnet sychronous motor, relying on smallvolume, simple structure, high air gap flux density, large rotational inertia, and many otheradvantages, is widely applied to aerospace, computer peripherals, electric cars and many otherfields. Therefore, the research on using direct torque control method for the effective controlof permanent magnet synchronous motor is particularly important.This paper is firstly to discuss the structure and characteristics of permanent magnetsynchronous motor, and to analyze coordinate transformation in different coordinate systemsof permanent magnet synchronous motor and its mathematical model, and to expound thebasic principles of direct torque control of permanent magnet synchronous motor. In the statorcoordinate system, it is to use flux linkage regulator and torque regulator and directly trackthe stator flux and torque, so as to control the inverter output voltage to obtain a faster torqueresponse. It is to detail analysis of the relationship between space voltage vector and motortorque, and stator flux. In the circumstance of MATLAB/Simulink software, it is to build eachsimulation module for direct torque control of permanent magnet synchronous motor and toconduct simulation analysis. The results show that when the motor is running at high speed,smooth flux linkage, low torque pulsation and other advantages are appeared,however, on thecontrary, torque and flux linkage produce pulsation.Against high pulsation of torque and flux linkage and inconstant switching frequencyexisting in traditional direct torque control, this paper is to research the direct torque controltechnology based on space vector modulation (SVPWM-DTC), which is to replace hysteresisloop controller in traditional direct torque control with PI controller and to control inverter with SVPWM. Using MATLAB simulation software to establish a simulation model of thesystem, the simulation results show that this method can effectively reduce pulsation of torqueand flux linkage, and presents fast response speed and strong anti-jamming capability, so theperformance of the control system has been improved.This paper, using none-sensor technology, is to design a model reference adaptive speedidentification scheme in the permanent magnet synchronous motor direct torque controlsystem based on Lyapunov stability theory. It also designs speed adaptive flux observer andestablishes the simulation model. Simulation results show that this scheme can achieve rotatespeed identification, speed can be accurately tracked and the robustness is pleasant. Therefore,the simulation result is relatively satisfying.