Study On The Practical Control Techniques For The Marine Shaft Brushless Doubly-fed Generator System

The brushless doubly-fed machine, short as the BDFM, is a new kind of AC excited double-fed motor, because the carbon brush and slip ring structures are left out, the maintainability and reliability of the BDFM is enhanced significantly. Compared to the traditional induction motor, the BDFM only use a lower capacity of converter, so that the cost of the hardware can be reduced. Also, the BDFM can be used in variable speed constant frequency electrical power generation system, so it has bright application prospects in marine shaft power field and wind power field. Now, what limits the development of the BDFM is the application of modern control strategy on the real system.This thesis mainly studies the problems of using the control strategies in the real BDFM power systems. First introduce the basic theory of BDFM, and the relationship of energy transfer. Than build the mathematic physical model of the BDFM according to its equivalent circuit. Later, the controlling model of BDFG was built in Simulink software. In the controlling model, the BDFM are modeling by S-function and Simulink modules. Based on the derivation and the establishment of a motor mathematical model, which means the establishment of the voltage source control model and the current source control model of power generation is running the dynamic simulation. By compared the voltage and frequency of the vector or scalar control strategy in different working conditions, the pros and cons of these two strategies can be told. The second part of this paper is experiment. Using a BDFM and several other equipments to build a BDFG system, and the scalar control strategy is used to control the system. In this experiment, in order to solve a problem that happened during the experiment, an idea of using the expert database to choose a proper PID parameter is raised. After taking the wave forms from the experiment equipments, the working pattern can be analyzed according to the wave forms.In the end, based on the results of simulation and experiment, analyze the outputs of the system using the scalar control strategy, a result can be told that the BDFM power system could work steady in the simple environment when using the scalar control strategy. When it comes to the marine shaft power system, the BDFM power system has good practicability. Meanwhile, building the off-line PI database create a fundamental tool for the next-step studying.