Research On The System Low-speed Electric Vehicle Intelligent Fast Charging

At present, the lead-acid battery has the advantages of mature technology, low cost, good output characteristic, large current charge and discharge, wide temperature range, so it is widely used in low-speed electric vehicles. But the short driving distance and long charging time are the two major factors hindering the popularization of low-speed electric vehicles. Battery fast charging technology is one of the key technologies for electric vehicle application effect, therefore, the research and design of electric vehicle charging technology of lead-acid battery has the extremely important theory significance and engineering application value. The main task of this paper is to study and design the electric vehicle lead-acid battery intelligent charging system, to achieve the purpose of fast charge.In this paper, the basic electrochemical battery charge and discharge characteristics of charging basic principle was analyzed, the charge method of conventional charge and current are studied, and based on this, puts forward the multi-stage intelligent charging method; Analyzed the PID control and neural network control theory, designed the PID control algorithm based on BP neural network; Analyses the DC chopper circuit topology structure and isolation converter topologies, determined using flyback topology structure and combination of Buck and the Boost circuit DC chopping circuitIn the hardware aspect, the scheme adopts the high frequency switch power supply circuit, chopper circuit and DSP circuit consisting of the main circuit and drive circuit, data acquisition circuit, auxiliary power supply circuit composed of auxiliary circuit, Before charging, the first measurement is environmental temperature, according to the calculation of temperature compensation voltage, when charging begin, collecting the charging current, voltage and other parameters of feedback to the DSP, DSP through the control algorithm of a charging cycle parameters, conversion and control of each stage. In the stop charging control, using the current control method and the negative voltage increment control method as the core, time control method for auxiliary stop charging control method, it can accurately determine the battery is fully charged, prevent overcharge, realize the intelligent,fast charging.