Study Of Permanent Magnet Synchronous Motor's Direct Torque Control System Based On Space Vector Modulation

Direct Torque Control (DTC) technique is a new type of control method after Vector Control technique. Permanent Magnet Synchronous Motor (PMSM) driven by triphase sinusoidal current is research object in this paper. This thesis hammers at reducing the torque ripple of DTC system and realizing the sensorless technique. By analyzing the torque ripple drawback of the PMSM DTC system, a new DTC strategy of PMSM based on observing error of stator flux linkage is proposed as well as the predictive current control for PMSM. Then the paper designs the realization schemes about these two control strategies emphatically. At the same time, it gives a simple and practical method to calculate the rotor position of PMSM.Firstly, the thesis introduces the structure and characteristic of PMSM briefly, and then gives the mathematics models of PMSM in various coordinate. On this basis, the principle of PMSM DTC strategy is discussed deeply as well as the realization approach. Then, it analyzes the torque ripple drawback of the PMSM DTC system as well as the sensorless technique. Combined with space vector modulation technique, this thesis presents two aforesaid control strategies to restrain torque ripple as well as the estimation of the rotor position.Secondly, this thesis sets up the sub-module of PMSM DTC system by Matlab/Simulink. Through the simulation of the system, we can find that the emulational waves are consistent with the theory analysis. The result of the experiment validates the feasibility of DTC technology on PMSM control system and the availability of decrese the torque ripple. At the same time, the simulation result shows that, the method to estimate the rotor position is precise when the speed of PMSM is above 10% of rated speed. It also can simplify the entire control system and reduce the calculation of processors. So this method has a certain practicality.Finally, based on simulation, this paper adopts the special chip of TMS320F2812 to control motor and Intelligent Power Model, designs software and hardware circuit of the PMSM DTC control system. The DTC for PMSM is implemented and the experiment results are concordant with those of simulation. This will be a base to study in the futuret.