Design And Development Of Power System For Plug-in City Bus Based On Composite Energy Storage

Plug-in hybrid is generally recognized for people because it can not only get a better energy-saving emission reduction effect but also has the same performance as the traditional vehicle.Plug-in hybrid vehicle has the same charging and driving functions as the pure electric vehicle while it also has traditional internal combustion engine,it is so complex and makes more difficult for system matching and controlling.At present,most of plug-in hybrids use batteries only as energy storage units,and the performance of vehicles is limited by the low specific power of the battery.The acceleration and braking are more frequently for a city bus,so the energy storage unit must more performance in a Plug-in city bus and single battery energy storage can't meet the vehicle performance and the use of life cycle requirements.Therefore,the study of advanced composite energy storage matching and control technology is the key to the development of plug-in power system for urban buses,and also the key to solve the technical bottlenecks and realize the industrialization promotion of plug-in city bus power system.The article Bases on the national "863" project "plug-in city bus industrialization technology research",with the system design method,researching the composite energy storage and matching method for plug-in city bus power system,and the solution for the system components configuration and parameter calculation.The plug-in power system matching method based on the demand of the working cycle is established.The main configuration of the system is determined by the input of the working condition,which makes the development more targeted;avoid the lack of performance or over design.Proposed based on the super capacitor and battery composition of the composite energy storage system solutions,energy storage system by the battery,capacitor structures constitute a dual voltage composite energy storage platform to solve the current energy storage system,the prevalence of low power density,low efficiency,the battery life short problem.The energy distribution technology of a plug-in hybrid bus based on the best energy consumption is used to find the best energy flow path through the energy flow analysis in the process of vehicle operation to realize the optimal energy consumption of static and dynamic system.The intelligent mode switching algorithm based on the judgment of vehicle running condition is developed,which makes use of the limited energy of the energy storage unit,increases the engine downtime and solves the problem of frequent engine startup.The parts and the system test are completed,and the rationality of the design matching is verified.The test data are analyzed and the optimization ideas are put forward,which provides a reference for the subsequent technology development.