Multi-module Parallel Charging Device With Active Power Factor Correction

As the developments of vehicles during the last hundreds of years,all aspects of technology have been mature.While the increasing awareness about environmental protection among the public,green energy has become the focus of the development of current electric automotive.In order to improve the environmental problems brought by the emission of traditional automobiles,cars powered by electricity have come into being,Which use various types of batteries as energy carrier.Controllability,stability and safety of electric vehicles are very excellent,they are widely accepted and focused due to their zero emissions,pollution-free and reproducible properties.In this paper,a multi-module parallel charging device with active power factor correction is designed for the hottest electric vehicles.Harmonic is the main source of pollution in the power electronic devices,in order to eliminate harmonic pollution essentially and decrcase the switch loss,a efficient bridgeless type Boost power factor correction circuit topology is designed,by which the function of PFC with soft switch can be achieved.By using Buck circuit the charge control for types of batteries can be realized.Multi-module parallel charging devices can increase the capacity of DC power supply and reliability.In this paper details about principle of current sharing in parallel systems are analyzed,and the advantages and disadvantages of the commonly used current sharing control strategy are both compared,the average current sharing control strategy based on CAN bus is designed.The multi-stage charging mode is adopted to charge the lithium-ion battery,which solves the problem that the traditional charging mode is not ideal for the lithium-ion battery.According to the charging characteristics of Li-ion battery,the switching threshold of each stage in the charging curve is determined,and the PI controller based current single-loop and current-voltage dual-loop control are performed.The small signal models of APFC converter and Buck circuit are established.The voltage and current controller in control system are designed by using the frequency domain method.The main parameters of the circuit are calculated,and select the specific device models are also selected.Circuit modes are simulated by using MATLAB/SIMULINK,and the correctness of designed topology and control strategies are verified finally.Refer to the design indices of the input and output electric paramaters,a power factor correction module based on UC3854 chip,a DC-DC module based on the digital controller STM32F407 as the core control system and three modules parallel electric vehicle charging device are constructed.Based on the theoretical analysis and simulation,a single-module experimental prototype is built,several critical experiments are realized,hence the rationality of calculated circuit parameter and the correctness of control strategy are validated.