Research And Implementation Of Buck-boost PFC Car Charger

In the face of the energy and environment problem,the electric cars,being energy conservation and environmental protection,attract the world attention and become a research hotpot.The key of electric vehicle technology lies in the battery and charging technology.The traditional car charger can't charge the battery in too low voltage,so designing a car charger can charge the battery over discharge is meaningful.The thesis design a Buck-Boost charger with PFC.The main content includes:Overall design of the Buck-Boost PFC charger.Analyzing the existing car charger topology,the thesis put forward a new Buck-Boost PFC topology.The circuit is simple and can charge the battery in normal condition or over discharge.Control methods of two work modes and mode switch of the topology are designed.It proposes three inputs(voltage difference,voltage change rate,temperature protection)fuzzy controller to control charging current.This charging method can charge quickly,and can control the temperature rise.Design of the hardware of Buck-Boost PFC main circuit and control circuit.The character of public used components and operation character of the circuit is analyzed.The main circuit parameters are calculated,components are chosen.Voltage collection and current collection circuit and designed.Algorithm design and simulation of Buck-Boost PFC charger.The thesis analyses voltage loop and current loop of Buck-Boost PFC.MATLAB is used to simulate the two work modes and mode switch of Buck-Boost PFC,and the results indicate that the design is correct.The fuzzy controller,a combination of two two-dimension fuzzy controller,is designed to control the charging current.The simulation of charger system verify the function.Programing and experimental verification.DSP program,including main program and interrupt program,are programed.According to the parameters of structures designed,the experimental platform was built.The experiment results of the charger platform verify the feasibility of topology structure and the charger control algorithm.