Design Of Brushless Doubly-Fed Generator And Research On It's Control System

With attachment importance to energy source scarcity and environment pollution the wind electric power generation has developed dramatically all over the world. So the generator which is suitable for wind power generation attracts more attention now. The brushless doubly-fed generator (BDFG) has several obvious advantages. The BDFG has simple structure dependable fastness; the converter has smaller capacity and the lowered cost. The BDFG has no brushes and slip rings, so the reliability is improved. Accordingly, it has theoretic significance and practical value in studying BDFG of wind power generation.In this paper, firstly, we analyze special structure which is different from normal induction motors, and based on BDFG fundamental equation, the dissertation creates equivalent circuit and internal power relationship in different states; secondly, according to the characteristics of BDFG, the optimal design projects of squirrel-cage rotors structure are based on conventional design principle of AC machine. Take a machine with 6kW (3+1) poles for example, the BDFG is designed and the software is used to prove the rationality of the brushless doubly-fed machine. According to winding function method, we get the induction parameters of BDFG through software ANSOFT; thirdly, in order to illuminate the characteristic of electric power generation, the dq model of BDFG is established on the rotor reference frame, the performance in various operation modes are simulated using the MATLAB. The rationality of model and parameters of BDFG is proved based on all the work mentioned above; finally, a vector control method of BDFG is studied, which decouples active power and reactive power of power winding by controlling current of control winding, and also built the simulation model of VSCF control system for BDFG. The simulation result verifies the validity of model of BDFG system and efficiency of vector control strategy based on flux linkage orientation of power winding, which lay a theoretical foundation for further research of BDFG wind power generation system.