Research On PHEV Compound Power Source System And Vehicle Energy Programming

Plug-in Hybrid Electric Vehicle (PHEV) has a relatively small traction batterycompared to pure electric vehicle, so that the PHEV battery has a number of issuesof high discharge rate, large depth of discharge and fast aging. The series PHEV citybus is chosen as a research object. A compound power system which includes powerdistributing strategy and an vehicle energy programming method is developed toextend battery life and improve vehicle economy performance.The compound power system which adopts ultra-capacitor is utilized to stabilizepower battery current and to improve dynamic performance of power system. Anadaptable power distributing strategy is built by designing DC converter outputcharacteristic, so that power can distribute reasonably between power battery andultra-capacitor in real time. This power system is verified by both simulation andexperiment. Some improvements have been made according to the test result.An energy programming method based on prediction of future driving conditionis developed. Assistant Power Unit (APU) is started and stopped to make sure thatpower battery works in a durable and high efficiency region and thus has an extendedlife. The city bus which makes full use of parking time to charge has higherelectricity utilization ratio and lower fuel consumption. Simulation result shows thevehicle use cost under this energy programming is close to theoretical minimumvalue.