Research On Control System Of Brushless Doubly-fed Machine As A VSCF Generator

In wind power,marine shaft and other VSCF power generation fields,the programs that use the higher direct drive synchronous motor(permanent magnetic or electric field)plus the full capacity of the drive are of lower cost and overall efficiency of the system.Using the solution of wound rotor induction motor(brush DFIG)plus part of the capacity of the inverter can solve these problems.However,the slip rings and brushes on the rotor have an impact on the reliability of the system with post high maintenance costs.BDFM adopts the way that uses power grid supply and variable frequency power simultaneously while feeding,with adjustable power factor,excellent four-quadrant operation capability,high reliability and it doesn't need the converter to provide full power,The only requirement is ‘slip power',which makes the small capacity of the inverter and greatly reduces the cost of the entire system.In recent years,the architectures,mathematical models and control strategies of BDFM motor have been studied in depth.Base on the achievements of previous studies,the wound rotor BDFM designed by the tooth harmonic generation method according to the principle of VSCF has been studied in this paper.The main contents include:Studying the structural design of BDFM,analyzing the basic principles and several operation modes of BDFM,and deriving the mathematical model and equivalent circuit diagram of BDFM;Studying the structure of power generation control system of BDFM,putting forward a dual-loop scalar control algorithm based on the mathematical model of BDFM,and improving the dual-loop scalar control algorithm to further study a control algorithm of direct compensation load reactive current in the inverter side which improves the dynamic response performance of the system and takes the phase tracking method to grid connection;Using Matlab/Simulink to simulate the control algorithms to verify the feasibility of the algorithm;designing a BDFM control circuit board based on TMS320F28335 chip to analyze the main function and module of the control circuit board;Building an experimental platform for BDFG control system,conducting power generation experiments of BDFM at variable speed,variable load and grid connected state,which demonstrates the reliability of BDFM.