The Study On Analysis Of Efficiency And Simulation Of Brushless Doubly-fed Machine

The brushless doubly-fed machine(BDFM)is a new type of induction machine andcan easily realize asynchronous, synchronous and double-fed operation modes．TheBDFM has wide application prospects in respect of driving windmills or water pumps toperform speed-adjusting and energy-saving operation. So the study of BDFM is regardedvery important by many researchers.The study of BDFM is proposed in this paper．The main work of the paper is asfollows．Firstly, with the understanding of the development history, researching actuality andapplication prospects, combining with the literature in china and abroad, the basic theoryof BDFM is studied．In this paper, the operational principle of BDFM is analyzed in detailand the equations of the rotor speed,power and rotor frequency are derived．Secondly, the efficiency of BDFM is analyzed in its structure. Because the stator ofBDFM is composed with power winding and control winding, two winding modes aregiven and moreover, pole-pair selection, design of stator windings, the combination ofslots of stator and rotor, structure design of rotor, harmonic distribution of stator and rotorand decreasing of higher harmonic are also discussed in detail.Thirdly, there is not any directly coupling in electric-magnetic in the two sets ofwindings due to the speciality of BDFM's structure. The electric-magnetic power istransferred indirectly through rotor winding instead, so the analysis of steady stateperformance of BDFM is very different from that of conventional electric machines. Basedon the steady state model of the BDFM,this paper discusses the power flow inthe two stator windings and the rotor circuit under different speed ranges．The resultsobtained offer the theoretical basis to machine's design and selection of the capacity ofconverter．Finally, math model of BDFM is established and simulated．Based on the networkmodel, the BDFM d-q model is achieved. Then the Matlab/Simulink software is used andthe operation performance in various operation model is simulated．This provides thetheoretical foundation for the study of control strategy and implementation of this kind ofmachine in future.