Research On The Design Of Bidirectional DC/DC Converter Power Allocation Strategy For Super-capacitor And Battery Hybrid Energy Storage

In order to avoid the impact loss on battery when vehicle high power demand in accelerating or climbing condition,and to prolong service life of battery,the power allocation strategy of super-capacitor and battery hybrid energy storage for urban electric vehicles is studied in this paper.The power distribution module of hybrid energy storage is designed,and the model of super-capacitor and battery hybrid energy storage system is built,and simulating under prototype road test condition and UDDS condition,the power output characteristics of super-capacitor and battery are analyzed,and the “peak load shifting” effect of output power of battery is analyzed;The control circuit of bidirectional DC/DC converter is designed,the test platform is built to verify whether the performance requirements of the bidirectional DC/DC converter can be satisfied,and to verify whether the bidirectional DC/DC converter can control the power allocation according to the power allocation strategy.The main work as follows:As two kinds of different energy storage device,the working characteristics of battery and super-capacitor is analyzed,and the structure of hybrid energy storage based on battery and super-capacitor is analyzed and selected,the overall structure design is completed according to the design concept of the hybrid energy storage system.the overall structure of hybrid storage system is proposed according to the design idea of hybrid storage system.Parameters of battery and super capacitor are designed based on the analysis of the parameters of the prototype vehicle.The key parts of power divider,bi-directional DC/DC converter and power allocation strategy,are designed: According to the working environment of the bidirectional DC/DC converter,to guarantee the energy utilization rate of hybrid energy storage,the performance requirements of bidirectional DC/DC converter is proposed,the topology of bidirectional DC/DC converter is chose,and then the main component inductance and filter capacitor of bidirectional DC/DC converter are designed;Common power allocation strategy for hybrid power system are analyzed to design the power allocation strategy used in this paper.Battery and super-capacitor models are analyzed.In the Matlab/Simulink environment,the bidirectional DC/DC converter model is built from the point of view of hardware realization and PWM(Pulse Width Modulation)regulation,the power allocation strategy model for hybrid energy storage is built,and then the model of hybrid energy storage system based on battery and super capacitor is designed.In this paper,the performance simulation of bidirectional DC/DC converter is analyzed,and power supply simulation of hybrid energy storage system under prototype road test condition and UDDS condition is carried on,to analyze the power output characteristics of battery and super capacitor in the process of vehicle driving,as well as the “peak load shifting” effect of output power of battery.To design bidirectional DC/DC converter control circuit,appropriate processor is selected as the control chip,the voltage and current sampling devices is selected and the sampling circuit and signal conditioning circuit are designed,and appropriate IGBT driver chip is selected and the driving circuit is designed.The experimental platform is built and test is accomplished to analyze the performance of the bidirectional DC/DC converter,and whether the bidirectional DC/DC converter can control the power distribution according to the power allocation strategy.