Direct Torque Control (DTC) Techniques For Dual Three-Phase Permanent Magnet Synchronous Motor

The greatest strength of the Multi-phase Permanent Magnetic Synchronous Motor (PMSM) variable frequency and variable speed system is the high reliability, and this reliability makes the system to be one of the emphasis of research in electric drive fields. Currently, the application of multi-phase PMSM focuses on military and high reliability, high power situations. Direct Torque Control (DTC) has become an accepted advanced control method beside the current vector control. DTC is used for induction motor initially, afterward, this theory is gradually applied to the permanent magnet synchronous motor control. Especially in recent years, it has been introduced successfully to multi-phase PMSM. At the same time, multi-phase PMSM control strategy become to a new class.First of all, the thesis analyzes the development and the actuality of PMSM. Then, the mathematical model of dual three-phase PMSM on six-phase stationary reference frame have been proposed. The decoupling voltage vector space theory is introduced. By the use of coordinate transformation theory, it changes the mathematical model of six-phase PMSM on six-phase stationary, coordinates to the Mathematical model based on synchronous reference frame system that permanent flux linkageΨf to d axis.Secondly, the principle of the dual three-phase PMSM direct torque control system is expatiated in detail. Then the modular structure of the system and function of each module are also introduced. For the three-phase PMSM direct torque control system, this paper made a number of innovative theories, including space vector selection and analysis, determination of optimal switching table, and the zero voltage vector switching table. Based on widely reading of references, the realization of other modules and certain solution to the problem are introduced. For the stator voltage, DC current detection process drift, low-pass filter is designed based on series compensated flux estimator. It can solve the DC drift due to flux estimation error caused the problem. Solve some of the ways on the magnitude of stator flux and the load angle limit. On this basis, a set of dual three-phase PMSM direct torque control of the concrete implementation plan, and under this scheme is established based on Simulink (Matlab) of the simulation model, and the control scheme were simulated. Experimental results demonstrate the feasibility of the program in theory.Finally, several hardware and software algorithms of the control system are proposed. And in this paper, the experimental system of design dual three-phase PMSM direct torque control based on DSP is developed. The experiment proves that the system can achieve the expected results requirements, and simultaneity verifies the theoretical correctness and practical.Following on the study of induction motor and PMSM direct torque control, this thesis discusses principal issues of the dual three-phase PMSM DTC, and some valuable experiences and significant conclusions are given, which found the basis of the project for the further studies and extension.