Investigation Of The Control For Brushless Doubly-fed Machine

The Brushless Doubly-Fed Machine(BDFM)is a new-style machine.It has diferent design technology and control strategy from traditional induction machines. The BDFM system has the simple and firm brushless mechanical configuration and controllable power factor and doubly-fed electricity of the rotor and diversiform run mode as well as the latively low rating power converter.Therefore,it is a promising energy-saving adjustable speed drive system,which is specially suitable for electricity genetation with some reproducible resources, With more and more attention nowadays,it is of great singnificance to study the BDFM deeply.In this thesis,a detailed introduction of BDFM with a new type of rotor structure is presented,including the origin of BDFM,its development,current situation,research significance as well as its application. Then,other features of BDFM,such as the structure of stator and rotor,its operational principle,operating mode and power distribution,are also introduced in this thesis.Three mathematical models of BDFM,namely the nested loops model,the two-axis model in the rotor reference frame and the hybrid reference frame model,are compared and analyzed in this thesis. Expecially,the two-axis model is focused on and a simulation model of BDFM for the open-loop system is established by the software MATLAB/Simulink.Laboratory experimental system under open-loop are built to verify diferent operation mode's dynamic performance for the BDFM.Basesd on the successful two-axis model in the rotor reference frame,the vector decoupling model is educed through the reference frame transform and the directional magnetic field of the power winding and control winding on each synchronous reference frame.In this paper the control system based on vector decoupling model is simulated and the complete decoupling control of torque and flux is achieved accordingly.The simulation results acquire favorable control performance and attest to the feasibility and validity of the vector decoupling control of BDFM.