The Research Of Key Technologies In Indirect Torque Control System Of Brushless Doubly-fed Machine

The brushless doubly-fed machine is a new kind of AC motor. The structure was similar to the structure of cage rotor asynchronous motor, it doesn’t have carbon brush slip, but it can be operate in the way of doubly-fed. It could not only be operate as electromotor in AC speed control system, but also could be operate as generator in variable speed and constant frequency electric system It has the characteristics of small capacity of frequency converter and adjustable power factor. It is especially suitable for wind generators and pumps control energy-saving system and VSCF wind power fieldThe theories was based on the existing basis of theory, made deep research to the mathematical model of brushless doubly-fed machine, and made theory analysis on the brushless doubly-fed machine of indirect torque control system and reactive power control. Made study on the method of magnetic chain observation based on the existing indirectly torque control system of brushless doubly-fed machine of the laboratory, reduce the pulse of torque and speed, running in the low frequency and made research on the control of reactive power. The main work of the paper as follows:1.The mathematics model was important theory basis for the research of brushless doubly-fed machine, it play an important role in the analysis of control strategy. This paper was made deep study on the brushless doubly-fed machine more circuit model, the rotor speed model, power winding model and control winding model, derivate static model of double coordinate system based on these models. The applications advantage in the brushless doubly-fed machine direct and indirect torque control system of the model was the control system avoid the rotation of coordinate transformation. The paper was made simulation on MATLAB, the result of the simulation proved the validity of the model of double static coordinate system.2.The paper was made theory deduce on the torque control of cage the brushless doubly-fed machine indirectly torque control system which was based on the winding static coordinate mathematic model of the brushless doubly-fed machine control.3.Flux observer played a decisive role for the stability of the BDFM indirect torque control system. This paper studies the low-pass filter and the high-pass filter series method, orthogonal nonlinear flux observation method, and the orthogonal nonlinear flux observation method was improved, made it more suitable for indirect torque control system. On this foundation, two kind of flux observation method were used to power winding and control flux measurement. The stability of the system was improved and the torque and speed fluctuation were reduced. The super low frequency operation with a case of0.5Hz was realized. The experimental results show that the system had the performance of resisting the load disturbance.4.The control of reactive power can improve the power factors of the power winding and reduce energy loss of the BDFM, and it also was the basic function for the electricity generation of the BDFM. The controlling of Reactive power based on the indirect control system of the BDFM was deduced in this paper, the structure of the control system was built, the simulation model of the system was calculated in the MATLAB. The simulation result proved the effectiveness of the reactive power control.5.The paper was programmed and realized the research based on DSP TMS320LF2407A brushless doubly-fed machine experimental platform of the laboratory. The result of experiment shows that the steady state performance was improved because of the improvement of magnetic chain observation method and decreases of torque and speed pulse. In the control of reactive power, it was realized the adjustment of reactive power in the condition of invariable active power.