Permanent Magnet Synchronous Motor Direct Torque Control Technology Applied Research

In the alternator control system, magnetic directional vector control, as conventional dynamo control tactic, greatly improves its control capability by means of decoupling the flux and torque of the alternator via vector transform, as the way DC dynamos work, and it has become a current fundamental control method for the alternator. However, owing to the impossibility of the accurate observation of rotor magnetic linkage , the features of the system depends on parameters of alternator so much that coordinate transform is too complex in simulating DC dynamo control procession, which make the theoretical analysis unable to meet actual control results.Although the classical control system of direct torque control method, to a large extent, solves the problems, such as complexity in computing, liability to be distracted, and unsatisfactory actual performance, the torque ripple is too big and the output performance has also been influenced, when the alternator works at a low speed. To improve dynamic and static performance of direct torque control, the paper analyzed the structural principle, mathematic model, and work formula of the Permanent Magnet Synchronous Motor from rudimental theories, for the purpose of eliminating torque triple and enhancing low speed performance of the system through transforming coordinates and alternating vector control tactics.Meanwhile, the paper expatiated rationales of PMSM-DTC, definitely explained the conception of space voltage vector as well as its track control, and also simulated torque ripples of conventional DTC system via MATLAB/SIMULINK by establishing models of inverter, voltage vector, and stator magnetic linkage. From then on, the paper studied the modulating tactic rudiments of the space voltage vector, and put forward improvement methods based on the two SVM-DTC systems of reference voltage vector and reference magnetic linkage. Through simulation analysis, it proved its possibility and efficiency of such tactics in restraining torque ripples.