| V2G technology is an effective way to promote the consumption of new energy and orderly charging of new energy vehicles through the interaction of vehicle and electric network energy,and reduce the charging cost of car owners and the construction cost of power grid energy storage station.V2 G vehicle-mounted bidirectional converter is the core bridge of two-way energy interaction between power grid and new energy vehicles.With the development of 800 V architecture of electric vehicles,the characteristics of large voltage changes,short-term high-power charging and high reliability put forward higher requirements for vehicle-mounted bidirectional converter.In addition,the vehicle-mounted converter has high efficiency,strong anti-interference ability and high-quality power quality,which still has huge room for improvement.However,the complex operating conditions of electric vehicles,the battery is vulnerable to environmental temperature,and the control effect of traditional control algorithms is significantly reduced,as well as the unreasonable topology configuration,which limits the development of V2 G vehicle-mounted bidirectional converter to a certain extent.In this thesis,the totem pole bridgeless PFC and CLLC resonant converter are selected to construct the V2 G two-stage vehicle-mounted bidirectional converter,which can realize the energy interaction between the vehicle and the power grid in a short time,large power,wide voltage range and complex working conditions.At the same time,combined with the advantages of digital control with online parameter adjustment,power management and convenient programming and transplantation,the auto-disturbance rejection control strategy of the V2 G vehicle-mounted converter is studied.The main research work of this thesis is as follows:(1)On the basis of analyzing the development status of V2 G technology,this thesis compares the advantages and disadvantages of the existing bidirectional converter topology and application scenarios,and summarizes the technical status of the algorithm advantages,application status and parameter tuning of the active disturbance rejection control technology.(2)In order to meet the demand of short-term high-power,wide voltage range and energy bidirectional interaction under complex working conditions of V2 G technology,totem pole bridgeless PFC and CLLC resonant circuits are selected as the front AC/DC and rear DC/DC circuits of V2 G vehicle-mounted bidirectional converter.The working principle of two-stage circuit is analyzed,and the topology power factor correction,voltage gain and resonance characteristics are analyzed.Based on the analysis of the topology working mode,the mathematical models of the front and rear circuits are established by using the state space method and the extended function description method,which provides a theoretical basis for the subsequent design of ADRC.(3)Aiming at the problems of poor anti-interference performance,large voltage fluctuation,high total current harmonics and slow system response of V2 G vehicle-mounted bidirectional converter under the influence of battery output characteristics and power dynamic demand changes,a control strategy of V2 G vehicle-mounted bidirectional converter based on linear auto-disturbance rejection control is proposed.This strategy uses PI as the current inner loop and LADRC as the voltage outer loop to form a double closed-loop control structure.The controller of the front and rear circuits are designed respectively,and the parameter setting is explained.On this basis,in order to solve the problems of uncoordinated power transmission and system oscillation caused by the independent design of the front and rear controllers of the traditional two-stage converter,a joint optimization strategy of control parameters is proposed.This strategy first establishes the integrated mathematical model of the V2 G vehicle-mounted bidirectional converter based on the frequency sweep method,and then completes the controller design of the integrated mathematical model,Genetic algorithm is used to jointly optimize the parameters of the controller to obtain the optimal control parameters.Finally,based on Matlab/Simulink simulation platform,the simulation analysis is carried out under the conditions of sudden load change and given voltage change,and the results show that the proposed control strategy has stronger anti-interference performance and dynamic performance,which verifies that the proposed control method has better control quality.(4)In order to solve the defects that the linear ADRC cannot meet the wide range of output voltage under fixed control parameters,and the state observer cannot effectively observe the disturbance in the full load range,this thesis introduces fuzzy reasoning into the LADRC controller,and proposes a fuzzy linear ADRC strategy.This method realizes adaptive control by controlling the proportional gain coefficient of linear ADRC with a fuzzy variable,which greatly facilitates practical application.Based on Matlab/Simulink simulation platform,the control effects of traditional PI,linear auto-disturbance rejection control and fuzzy linear auto-disturbance rejection control are analyzed through simulation.The results show that the self-tuning of LADRC proportional gain coefficient through fuzzy reasoning can effectively solve the disturbance problem caused by load changes,with faster response speed,significantly improved anti-interference ability,and significantly improved system dynamic performance and steady-state performance,compared with the existing research results,this method has lower THD.(5)Based on DSP28335,a 3k W V2 G bidirectional converter experimental prototype is built,and the loss of its Si C power transistor is analyzed and calculated.On this basis,aiming at the power loss caused by the lack of synchronous rectification control and the shortcomings of traditional synchronous rectification control,a resonant circuit synchronous rectification control method based on the combination of resistance voltage divider and high-speed voltage comparator is proposed.Finally,the scheme is proved to be simple,efficient and low-cost.In order to test the actual control effect of fuzzy linear auto-disturbance-rejection control in the prototype,the startup test and wide voltage output test are carried out respectively,and the comparison test with the traditional PI algorithm is carried out under the conditions of sudden load change and given voltage change.The experimental results verify that the proposed control strategy has better control performance,can effectively shorten the system response time and improve the system anti-interference ability. |
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