Research On Energy Management Strategy For Dual Source Trolleybus

Development of new energy bus is an important way to solve the environment pollution and the depletion of oil resource, dual source trolleybus has developed rapidly with the advantage of environmental protection, energy conservation and good dynamic performance. Beijing city has made use of existing trolley bus resources, combined with electric vehicle technology, achieving application of dual source trolleybus working in the wireless network with battery. However, the problems of battery’s low power density and short cycle life have a bad effect on dynamic performance and driving range of dual source trolleybus. Supercapacitors have the advantage of high power density, rapid charge and discharge performance, long life time and wide working temperature, which combined with battery and been used in the energy storage system of dual source trolleybus. The peak power is provided by supercapacitors during on-line working mode to reduce the load pressure of the network, the use of supercapacitors during off-line working mode can not only reduce the damage of large charge and discharge current to the battery, but also improve the vehicle’s dynamic performance, maximum recovery the braking energy, and extend vehicle driving range.First, this paper analyzed the performance characteristic of various power batteries and supercapacitor and compared the strengths and weaknesses of each performance. According to the performance characteristics of the trolley bus, the hybrid energy storage system of lithium battery and supercapacitor is chosen as the vehicle power source for the trolley bus. Subsequently, the characteristics of the lithium battery, super capacitor, bidirectional DC/DC converter were analyzed, the equivalent model of each components were established in Matlab/simulink, and the charging and discharging performance of the hybrid energy storage system with high power pulse charge and discharge conditions was tested. Secondly, the structure of trolley power system with lithium battery-supercapacitor hybrid energy storage system was analyzed, also, the power performance of dual source trolleybus was analyzed form two aspects of force and power demand, and several typical driving cycles were introduced. Thirdly, according to the dynamic performance requirements of the vehicle, the parameters matching and optimization of the trolley bus power system were carried out. Finally, the energy management strategy of the dual source trolleybus was studied, global optimization energy management based on dynamic programming control strategy was designed. Through the ADVISOR simulation software, the simulation model of the whole vehicle was carried out, and the simulation results of the dynamic programming method and the control strategy based on the rules were compared and analyzed. The simulation results show that the energy management strategy based on dynamic programming can better utilize the advantages of the supercapacitor, reducing the peak power of network power, making the power output of the lithium battery relatively stable, and more effective recovery of braking energy, reduce the energy consumption, improving the vehicle’s dynamic and economic performance. In addition, the fuzzy control rules were formulated by the control results obtained by the dynamic programming method, and the fuzzy controller was designed, and the effectiveness of the fuzzy control strategy was verified by simulation.