Study On The Mathematic Model And Vector Control Of Doubly Fed Brushless Machine Based On Slip-Frequency Rotating Reference Frame

Brushless doubly-fed machine(BDFM) adjustable speed system has the benefits of the cage rotor induction machine adjustable speed system and the wound rotor induction machine adjustable speed system. In particular, the inverter rating is only fractional rating of the BDFM, which has significant cost advantage.At present, the researches on BDFM and its control method are in the stage of transition from theoretical research to practical application, so there are lots of aspects needed to be improved and developed. There is no analysis method that includes the vector diagram, equivalent circuit and mathematical model together. Aiming at the problems needed to be settled, the contents of this thesis are following:Firstly, on the basis of the other scholars' researches, the method of establishing mathematical model was put forward based on the slip frequency rotating reference frame. The mathematical model has solved the different rotating speed problem between the two rotating magnetic fields produced by the power winding and control winding currents.Secondly, based on the mathematical model of the BDFM in the slip frequency rotating reference frame above mentioned, the vector control method of BDFM based on slip frequency rotating reference frame was put forward. The active and reactive component of the power winding current can be controlled by the control winding current, which could not only adjust the power factor of the power winding, but also make power winding current only providing active current component, and the power winding supplying the dynamic torque. The exciting field for the power winding was completely provided by the control winding. Therefore, the adjustable speed system could provide the greater dynamic electromagnetic torque, and largely enhance the dynamic response performance.Thirdly, the vector control system prototype of the BDFM based on slip frequency rotary coordinates system was designed, and the experimental study was carried out. The experiment results have verified the correctness of the proposed vector control system of the BDFM based on slip frequency rotating reference frame.Finally, a new equivalent circuit of the BDFM was established, which could solve the separation problem of the power winding and control winding, and greatly provide the convenience for steady-state analysis of the BDFM.