Linear Active Disturbance Rejection Control Based On DC Output Voltage Of VIENNA Rectifier

Under the background of "Dual Carbon",China has been actively promoting the upgrading and transformation of energy structure.One of the major measures is to replace traditional oil vehicles with electric vehicles.The rapid development of electric vehicles promotes the collaborative development of charging piles.The core structure of the charging pile is the rectifier device.The VIENNA three-phase three-level rectifier is widely used in the front rectifier of Electric Vehicle(EV)grid-connected charging system due to its advantages such as low current distortion on the grid side,low load bearing of switching devices and easy control of DC bus voltage.When load mutation,power grid voltage fluctuation or internal parameter change occurs in the stage before rectification,the output voltage of the dc side of the rectifier will also fluctuate,resulting in instability of the whole system,thus resulting in the reduction of EV charging power quality.Therefore,this paper mainly studies the control performance of different control strategies in the VIENNA six-switch rectifier.In this paper,the VIENNA rectifier with six-switch tube is taken as the research object.Firstly,the working principle and topology of the VIENNA rectifier are analyzed,and three mathematical models in different coordinate systems and three equivalent circuits are derived.According to the mathematical model of rectifier,a double closed-loop Proportional Integral control(PI)system was designed.Due to the inherent contradiction between PI control overshoot and rapidity,in order to improve the response speed of current loop tracking,PI controller of current loop is replaced by Linear Active Disturbance Rejection Control(LADRC).Then,the convergence of LESO is analyzed in frequency domain.Finally,a simulation model is built in MATLAB/Simulink.The simulation results show that the control strategy adopted achieves the operation per unit power of the rectifier system.And has a good control effect.VIENNA rectifier double closed loop control voltage loop is susceptible to grid side voltage fluctuation,load disturbance,etc.In order to improve the immunity of the voltage loop,According to the mathematical Model,the second order LADRC is used as the voltage loop controller and the Model Compensation Linear Active Disturbance Rejection Control(MC-LADRC)is proposed to improve the LADRC,and then the optimization of LADRC immunity by Mc-ladrc is proved in the frequency domain.Through MATLAB/Simulink simulation system,the output voltage waveform of THE DC side of Mc-ladrc and LADRC under steady-state operation,network side disturbance and load disturbance is compared,and the control performance of Mc-ladrc is better than that of LADRC.In this paper,the simulation of three-phase VIENNA rectifier control system is carried out in MATLAB/Simulink.The results show that the proposed improved control method has good effect on the VIENNA rectifier system and optimized the control performance.It has practical significance for the application of VIENNA rectifier in engineering field.