Permanent Magnet Synchronous Motor Direct Torque Control Theory

As a convenient vehicle is the automobile, the quantity of it increases sharply and it does harm to the energy security and the environmental protection. More and more attention have been giving to the development of electric vehicle(EV) which is as smart as automobile in the world for the energy conservation and the environmental protection recently. Permanent magnet synchronous motor (PMSM) drive with drive-in-wheel model of EV has excellent performance. And there is abundant rare-earth storage in China. Developing Electric Vehicle with PMSM can take advantage of the resource of rare-earth and accelerate the exploitation of it. Direct Torque Control (DTC) is an advanced control method beside the Current Vector Control. Comparing with Current Vector Control, DTC has better performance and it is easy to apply the field-weakening control to PMSM in DTC scheme. This paper studied the DTC and the Direct Torque Control drive system of Permanent Magnet Synchronous Motor. As a drive system of EV, concerning the efficiency of DTC some efforts have been made to the drive.This paper mainly includes: Compared the DTC system of Induction machine and Permanent magnet synchronous motor, modeled the PMSM using the space vector theory, describe the theory of DTC of PMSM and set up the model of DTC in SIMULINK.Concerning the requirement of drive system in EV, described and proposed a simple stator flux linkage estimator for wide speed range, and the simulation results shows it works well. Studied the function of zero voltage vector which can improve the performance of the system in PMSM DTCThe selection of stator flux linkage to minimize the looser in PMSM and field-weakening of PMSM for widening the speed range have been studied. Simulation was carried out and the results meet the requirement of a drive of EV.