Study On Bipolar Control Of Switched Reluctance Generator System

Because of simple and sturdy structure,low manufacturing cost and good fault tolerance performance,switched reluctance generator has great advantages in wind power generation,showing broad application prospects.However,the frequentlyapplied asymmetric half-bridge power converters have poor versatility,uniform manufacturing standards,and high cost,which limits the application of switched reluctance generators.Due to wide application in AC motors and low manufacturing cost,three-phase full-bridge converters have become a mature and versatile standard drive module.However,applications and researches of three-phase full-bridge converters have limited investigation in switched reluctance generator systems.Therefore,this paper takes the control system of three-phase full-bridge power converter switched reluctance generator as research object,and investigates in the basic principle of bipolar control,excitation mode,the influence of changing control parameters,i.e.turn-on angle and turn-off angle and speed,on system output power and efficiency.Firstly,the research background is introduced,the advantages and disadvantages of switched reluctance generator in wind power generation are summarized.The research status of switched reluctance generator modeling,asymmetric half-bridge power converter and three-phase full-bridge power converter is described.Then,the structural characteristics of three power converters,i.e.asymmetric half-bridge,Hbridge and three-phase full-bridge,are analyzed and compared.The three stages of excitation,freewheeling and power generation in the operation of three-phase fullbridge power converter are analyzed.The voltage equation and torque equation under the operation of three-phase full-bridge power converter are deduced under bipolar operation,and the energy transformation in process of switched reluctance generator is analyzed.Finally,two excitation modes,i.e.three-phase three-beat and three-phase sixbeat,are introduced.The current circuit,power switching state and phase current direction of each excitation region are given under two excitation modes.The operation characteristics,advantages and disadvantages of two excitation modes are compared.The advanced winding series modes and the lagged winding series modes are analyzed.A 2-D finite element model of switched reluctance generator is built through the FLUX software.The current waveform of the bipolar control of three-phase full-bridge switched reluctance generator system is simulated by FLUX transient solver under different control parameters.The influence of the diffierent control parameters on the output power and efficiency is analyzed.An experimental platform of bipolar control of three-phase full-bridge switched reluctance generator system is built based on RTLAB.The experimental data of power efficiency and output power under different control parameters is obtained,and the experimental data is compared with the simulation data.The simulation and experiment results show that the switched reluctance generator system can keep smooth operation drived by three-phase fullbridge power converter with relatively high efficiently,which means that three-phase full-bridge can take the place of asymmetric half-bridge power converter under high speed.