Study On Doubly-Fed Brushless Machine Control Strategy Based On Equivalent Rotating Control Windings

The doubly-fed brushless machine (DFBM) is a new kind of electrical machine, which not only has the characters of simplicity, robustness and reliability but also could run in asynchronous, synchronous or doubly-fed operation modes. Compared to speed regulating systems using conventional AC machine, the DFBM system controls only the slip power of machine, a small fraction of the overall system power, through the stator control windings. So it will have widespread availability in variable frequency adjusting speed (VFAS) systems of wind machines and pump and variable speed constant frequency (VSCF) wind power and water power generating systems.The main works of this paper conclude the theory analysis, performance simulation and experiment study of the DFBM. Several parts are followed.Firstly, by expressing structure characters, operation modes and electromagnetic energy conversion, some basic concepts of DFBM are explained. Based on magnetic field modulation function of rotor, the generation process of effective air gap magnetic field components in machine was analyzed and electromechanical energy transfer mechanism of DFBM was expound.Secondly, according to magnetic field modulation principle of DFBM and previous productions of researchers, DFBM mathematical model is set up by using the way of equivalent rotating control windings. On the basis of this mathematical model, the simulation system is build by MATLAB/SIMULINK software. Afterward, the performances of starting up operation and stationary state operation modes (asynchronous, synchronous and doubly-fed operation) for DFBM have been simulated.Thirdly, control methods of DFBM are studied. Magnetic field orientation control strategy for wound rotor induction motor is introduced based on equivalent rotating control windings model. The rotational speed of DFBM could be accommodated easily by adjusting control windings current, and the response speed of machine is improved highly. Moreover, some initial investigations about intelligence control are developed also. Fuzzy PID control method is adopted, which boost up dynamic state performance effectively. And then, correctness of control strategy is testified through the simulation.Finally, partial design of hardware and software is carried through. The variable frequency adjusting speed systems is analysis by experiment which found on equivalent rotating control windings mathematical model. The feasibility of theoretic analyzing and simulation measures are improved by experiment results.