Research On Direct Torque Control Technology For Permanent Magnet Synchronous Motor

The permanent magnet synchronous motor(PMSM) is characterized by its smooth speed,fast dynamic response, strong overload capacity, high reliability, structure diversification,application range etc, and attaches great importance to by the people. In motor control technology, the direct torque control(DTC) overcomes many shortcomings and the insufficiency of vector control(VC), therefore has become the research focus areas.The thesis briefly introduces the background and significance of the subject. The researcher made a detailed description about the status of direct torque control technology.And then the basic working principle of PMSM DTC system was deeply analysed. According to the problem of the traditional space voltage vector switch table, introduced “zero voltage vectors”. Based on it, built the simulation model of MATLAB/Simulink. From the result of the simulation model, we can see that traditional PMSM-DTC system has the advantage of simple structure and fast dynamic response, but the same time, its flux, torque ripple, speed are large. How to improve the performance of the system, is currently the most need to solve.For the larger torque ripple in traditional system phenomenon, the fuzzy control is introduced to the system, the flux error and torque error are fuzzy, replacing the hysteresis comparator with fuzzy controller. So it can complete the selection of voltage space vector exactly. The simulation results show that shaft pulse of the Fuzzy control system is reduced,and the dynamic and static performance of the system are improved. In order to further improve the system performance, the existence of flux measurement problems are analyzed.The master thesis presents an integrated type based adaptive compensation flux observer, to further improve the accuracy of flux observation and speed. Firstly, the on-line identification of stator resistance by means of model reference adaptive control. Then an integrator based on adaptive compensation is established. It can eliminate the influence of DC bias and stator resistance. Finally, this method carries on the simulation research. The simulation results show that the integrated flux observer based on adaptive compensation can more quickly and accurately estimate the actual torque.Finally, this thesis presents a direct torque control system based on digital signal processor hardware and software design. The permanent magnet synchronous motor direct torque control platform is constructed. In conclusion, the fuzzy control and adaptive stator flux observer of permanent magnet synchronous motor direct torque control system, not only has the advantages of simple structure and fast dynamic response, but also reduces torque and flux ripple, improves the system dynamic and static performance.