The Study On Design And Simulation Of Brushless Doubly-fed Machine In Wind Power Generation

With the rapid development of Chinese economy, the contradictions between supply and demand of electricity become more and more serious. The wind power generation which is high efficiency, cleanly and multiform is a practical choice of energy development and the strategy of sustainable development, so the generator which is suitable for wind power generation attracts more attention now. The brushless doublyfed machine (BDFM) has several obvious advantages. The BDFM has simple structure, dependable fastness, adjustable power factor, reduced harmonic distortion of the supply and controllable operation as a generator. The converter has smaller capacity and the lowered cost. The BDFM has no brushes and slip rings, so the reliability is improved. Accordingly, it has theoretic significance and practical value in studying BDFM of wind power generation.In this paper, a research on the BDFM with cage rotor is developed. The operational principle of BDFM is illuminated and the software of ANSOFT is used to analyze the "magnetic field modulation" theory from the magnetic field angle. According to the characteristics of BDFM, the optimal design projects of squirrel-cage rotors structure are presented using the Finite Element Method based on conventional design principle of AC machine. Take a 20kw (3+1) poles machine for example, the BDFM is designed andthe software RMxprt is used to prove the feasibility of the squirrel-cage rotors machine. In order to obtain practical parameters of BDFM, the field-circuit coupling method is put forward based on winding function method and energy method and all the three methods are used to calculate and compare the induction parameters of the BDFM designed above.In order to illuminate the characteristic of electric power generation, the BDFM dq model is established on the rotor reference frame, the performance in various operation modes are simulated using the Matlab. The feasibility of model and parameters of BDFM is proved based on all the work mentioned above which provide a solid foundation forfuture work.