| Electric vehicle charger an important part of the new energy electric vehicles,directly affecting the use of electric cars.When the traditinal vec is charging,charging resistance is nonlinear and change accuracy is not high,causing the issues of owe charging,overcharge and so on.in this paper,the electric vehicle charger of a two-stage transform structure which employes a fuzzy PI control is designed,and the main purpose of safety and stability of the output voltage is arrived.The main research contents include:(1)The performance improvement of all aspects of Single-stage structure circuit is limited,but two-stage structure has better power quality and control effect.In this paper,the electric vehicle charger adopts two-stage structure because it is easy to realize control of power and increase power factor.(2)In the two-stage of structure,former level AC/DC converter is controlled by a dedicated chip,and after level indirect DC/DC converter circuit is controlled by DSP chip,and the main circuit and control circuit is designed.In this paper,using the digital design and the fuzzy PI control method,the double closed-loop fuzzy PI control is achieved in DC/DC converter.(3)In order to solve the problem of control parameters is bad to match the current load,this paper adopts the fuzzy PI control strategy,through real-time adjustment of proportional and integral,to improve the control accuracy and stability.The simulation experiment and the prototype test results show that this control method,compared with the previous conventional PI control,has smaller overshoot and steady-state error.First of all,basic function of various parts for the prototype is tested,and it shows that the prototype under the condition of open loop can work normally.Then the control effects of single,double closed-loop PI and double closed-loop fuzzy PI are compared.The experimental results shows that the steady-state error of the double closed-loop fuzzy PI control is around 0.01 V,and the overshoot volume is around 0.1%,proving that this results reach the expected effect.This article is helpful for study of electric vehicle charger. |
