Research On Electric Vehicle Battery Hybrid Source Charging Technology

As energy and environmental problems have become increasingly prominent, the electric vehicle with the advantages of low emission, low noise and etc gets more and more people's attention, and will have great development. But electric vehicle charger is a kind of nonlinear equipment, and will bring harmonic pollution to the grid; Besides, a big electric vehicle charging station will be a heavy burden to the grid. Currently it is the trend to use renewable energy for electric vehicle charging. Solar energy is one of the renewable energies, which are clean and have prospects for large-scale development, and China is richer in it. The solar energy is influenced by environment, temperature and weather easily, so the output is not quite stable. A hybrid charging system, in which the power grid and solar are complementary, is studied in this paper, and that has great practical significance.This system can be divided into three parts:photovoltaic independent system, commercial grid and the main circuit for charging. Because solar photovoltaic power output energy extremely unstable, in order to make solar cells output with maximum power in any case, the improvement of solar maximum power tracking speed is necessary. This method can shorten the recovery cycles of cost, and improve the system efficiency greatly. In this paper, based on the comparison and analysis of several common methods for most high-power tracking, the optimal gradient method is used, and proved to be effective through the simulation experiment. Electric vehicle charging equipment is a kind of nonlinear device, and will bring harmonic pollution to grid, so taking measure to reduce harmonic pollution is needed to improve the power factor of system. Currently, the charging speed of power battery in electric vehicle is slow, the charging efficiency is low, and the battery is damaged easily. The chemical characteristics of lead-acid batteries and traditional charging methods are introduced in this paper, and the method of positive and negative pulse intermittence for the accumulator is chosen. The improved Boost ZVT-PWM circuit is designed in this paper, and its working principle is introduced. This circuit is applied to the independent photovoltaic system, and the experimental results show that this circuit can greatly improve the working efficiency of the photovoltaic system. Boost active power factor correction is used on the Power grid side, and an average current control method is adopted. Matlab simulation results prove that the method can improve the system power factor obviously, and reduce system harmonic pollution to the grid. Buck circuit topology structure is adopted in the main circuit of charger, and this structure can achieve the work of positive and negative pulse intermittence for Accumulator. TI TMS320LF2407A is chosen as the main control chip in circuit.Simulation and experiment show that the hybrid charging system, in which the power grid and solar are complementary, studied in this paper, can be the guide and reference to the construction of the charging station.