Study For Cascade Brushless Doubly-fed Machine And Its Speed Control System Application

In practice, the driving system of pump and fan have a wide application range, but the largepower consumption, low efficiency, as the application of motor frequency speed control, theseproblems had been solved effectively, not only cost savings, but also to be good effect on thereliable equipment operation, but the application subject to certain restrictions because of the highcost of frequency converter. As a new type of motor, the cascade brushless doubly-fed motorrequires small converter capacity in the process variable frequency control, and the rotor doesn’thave the carbon brush and slip-ring structure, these excellent performances, have attracted more andmore attention of scholars.This paper deeply explores the CBDFM and its speed control system. Firstly, it introduces theCBDFM, including the basic structure and working principle, the difference from brushlessdoubly-fed machine and the derivation of mathematic model; then it discusses the CBDFM’s speedcontrol technology, expounds AC motor speed control mode and CBDFM’s speed controltechnology; secondly, this paper focuses on elaborating the application of CBDFM for the fan,pump load, and comparing with the traditional three-phase asynchronous motor frequency controldriving, proves its superiority; finally uses SIMULINK software to simulate the CBDFM.The analysis results show that, by changing the converter input, the system can achieve thepurpose of stepless speed regulation in a speed range. If given more energy in the future, the systemis expected to become an ideal kind of high efficiency, high performance and high ratio ofperformance driving method applicable to fan、pump load.