| Nowadays,energy crisis and environmental pollution are common problems the world has faced.With the increasing demand for environmental protection,traditional fuel-powered vehicles cannot meet the requirements of the times.In recent years,electric vehicles have achieved rapid development due to zero-emission,economical use and other factors,but the lack of mileage of electric vehicles is a potential factor hindering its further promotion.Plug-in solar electric vehicles can effectively solve the mileage anxiety of new energy vehicles,and is the development direction of the next generation of new energy vehicles.A plug-in solar electric vehicle can operate in a variety of battery conditions,depending on the SOC of the battery,whether the AC power is accessed,and the lighting condition.In order to make clear that photovoltaic cells how realize the Maximum Power Point Tracking(MPPT),efficient power transformation,smooth switching among different states when the working state of the battery is switched,it is necessary to carry out exploratory research on the charger topology,MPPT technology,and converter control technology.This topic focuses on the above issues.A three-port converter is selected as the plug-in solar electric car charger topology.The two inputs of the three-port converter are respectively the output voltage of the AC grid after the power factor correction circuit(PFC)and the output voltage of the photovoltaic cell,and the output port of the three-port converter is connected to the battery.The energy relationship and operation mode of the input and output ports of the threeport converter are analyzed,and the system control strategy to realize the stable operation of the three-port converter is proposed to ensure the optimal charging state of the battery.In order to prevent the overcharge of the battery,the competition mechanism is used to make the battery in constant voltage limit or constant current limit state when charging,prolonging the service life of the battery.On the basis of theoretical analysis,simulation is carried out to verify the feasibility of the proposed control strategy.Local shading of on-board photovoltaic cells of solar electric vehicles is a common phenomenon.How to realize on-board photovoltaic cells operating at the theoretical maximum power point is studied.After researching the photovoltaic cell MPPT control technology,an improved particle swarm optimization algorithm based on variable learning factor and variable inertia weight is designed,which realizes that the solar electric vehicle can track the maximum power point quickly and accurately under the condition of uniform or local shading.The MPPT model of the improved particle swarm optimization algorithm is established.The simulation results show that the improved particle swarm optimization algorithm not only outperforms the traditional algorithm in tracking speed but greatly improves the tracking accuracy.In order to verify the feasibility of the charging system theory and simulation of plugin solar electric vehicle,an experimental prototype of the three-port charging system based on STM32 control is built,and the software and hardware are designed respectively for the experimental prototype.The experimental results prove that the three-port converter operates efficiently,the energy distribution among the power grid,photovoltaic cells and batteries is in a relatively optimal state,and the proposed control strategy is stable. |
