Research On Variable Speed Constant Frequency Constant Voltage Control Of Brushless Double-Fed Motor

In the fields of wind power generation,hydroelectric power generation and diesel power generation,variable speed constant frequency power generation technology has replaced constant-speed constant-frequency power generation technology to become the trend and mainstream of market applications and academic research.This paper selects the brushless double-fed power generation in variable-speed constant-frequency power generation technology.System as a research focus.The brushless double-fed motor eliminates brushes and brush rings.It not only has the characteristics of simple structure and reliable operation,but also can reduce the capacity of the inverter and reduce the system cost.At present,the research on the control strategy of brushless double-fed motor mainly focuses on the frequency conversion speed control strategy for motor operation.However,the VSCF control strategy for brushless double-fed motor running as a generator is relatively rare.In this paper,the VSCF strategy and the corresponding speed sensorless algorithm of the brushless doubly-fed machine in independent operation and grid-connected operation mode are studied.The main research and innovation are summarized as follows:(1)Firstly,the development background of wind power generation field with the most widely used brushless doubly-fed machines and the research status of variable-speed constant-frequency power generation systems are introduced.Then the development process and research status of the body and its power generation control technology for brushless doubly-fed machines are introduced.a brief introdction.(2)The basic structure of the brushless double-fed machine,the principle of variable-speed constant-frequency power generation,the steady-state equivalent circuit and the power relationship are introduced and analyzed in detail,and the mathematics of the brushless double-fed machine in various coordinate systems are obtained.model.The dq biaxial mathematical model in the rotor-speed coordinate system was established by simulation and the basic operating principle of the brushless double-fed machine was simulated.(3)For the strategy of variable speed constant frequency control for brushless double-fed motors,the implementation of scalar control is analyzed in detail.Because there are many problems in the scalar control,the vector decoupling control strategy of the field orientation of the power winding is adopted,and an improved independent operation vector control strategy and grid-voltage oriented oriented grid operation vector control strategy are proposed.The vector decoupling control strategy is verified through simulation.(4)For the speed-sensorless control mode of independent operation and grid-connected operation,the frequency PI regulator and the model reference adaptive(MRAS)method are respectively adopted to realize the frequency-free control and the grid-connected power control.Aiming at the problems in the system startup and off-grid handover phases of MRAS speed estimation,a off-grid smooth handover algorithm combining phase PI regulator is proposed.Both simulation and experiment were verified.(5)Build a brushless doubly-fed power generation experiment platform and conduct hardware and software design and programming experiment debugging.Simultaneous simulation of various power generation conditions,independent operation,grid operation and corresponding speed sensorless control experiments.The experimental results were analyzed to verify the feasibility of the control algorithm.