With the development of China’s economy and the improvement of people’s living standards,the number of cars is increasing.However,under the dual influence of the pollution caused by traditional fuel vehicles and the global energy shortage,the use of electric vehicles instead of fuel vehicles has become a trend.However,electric vehicles are limited by their battery capacity,the cruising range is generally low,so it is necessary to develop and rationally arrange the charging facilities.The core of electric vehicle charging equipment is rectification.High-performance rectifiers can improve the charging efficiency of electric vehicles,ensure power quality on the grid side,and reduce key problems such as harmonic pollution of power grids.Usually,the charging of an electric vehicle is to convert electric energy through two stages,that is,three-phase alternating current to direct current,and then direct current to direct current.However,the two-stage charging process will damage the charging efficiency.Therefore,in this thesis,a quasi-single-stage three-phase three-port rectifier is studied,the efficiency of the system would be reduced by reducing the number of system power conversion stages,and different control strategies will be analyzed and compared.Firstly,according to the topology of the three-phase three-port rectifier,the mathematical modeling and double-closed-loop decoupling control under different coordinate systems are completed.Secondly,the implementation mode of the space vector modulation of the three-phase three-port rectifier is analyzed in detail,and the conventional three-level space vector pulse width modulation(SVPWM)is improved,in which,one is to reduce the computational complexity through the linear programming of the region,the other is that the space vector of the three-port rectifier is asymmetric,so it can not be simplified by using direct rotation.This thesis proposes a new method of block rotation,which further reduces its operation process.Thirdly,due to the time-varying and nonlinear characteristics of the rectifier system,the traditional PI controller has been difficult to meet the influence of the disturbance of the system in the complex environment on the operation of the rectifier.Therefore,based on the principle of direct current control,the voltage outer loop uses a fuzzy neural network controller whose parameters can be adaptively adjusted,the current inner loop uses a PI controller,and through the improvement of the fuzzy neural network controller,using fewer computer operations to complete better control of the DC side voltage,the steady-state and dynamic performance of the rectifier will be greatly improved.Finally,the overall simulation model of the three-phase three-port rectifier control system is built in this thesis.While completing the basic functions of the three-phase three-port rectifier,it is also verified that the rectifier system is controlled by the improved fuzzy neural network controller under different working conditions,it is shown that the control strategy of this system is superior to the traditional PI control. |