Modeling And Simulation Research On Hybrid Energy Storage System For Pure Electric Vehicles

With the advantage of zero emission, the pure electric vehicle has been chosen to be developed as a key one among all types of EVs by many governments. However, the power battery currently has shortcomings of low power density, short cycle lifetime, and not suitable for high-rate charge and discharge, therefore the pure electric vehicles has low dynamic performance and high usage cost. In recent years, ultra-capacitor energy storage technology has got rapid development. On the one hand, due to the rapid charge and discharge performance, high power density, long cycle lifetime, high efficiency and ability to work in a wider temperature range, ultra-capacitor has been widely used in electric vehicles as power device and energy storage device. On the other hand, low energy density and high cost make it incapable of being the independent power supply for the EVs. In this regard, this paper combines the ultra-capacitor and power battery into a hybrid energy storage system, then studies the parameter matching, modeling and simulation of the system used in a pure electric passenger car.First, this paper elaborates the general situation on the development of electric vehicles, and summarizes the research status and existing problems of the hybrid energy storage system applied in vehicles. Therefore this paper chooses a pure electric passenger car as the object model to research the hybrid energy storage system. By analyzing the characteristics of the power battery, ultra-capacitor and bidirectional DC/DC converter separately, comparing the analysis of the hybrid energy storage system and single power battery storage system, the advantages of ultra-capacitor-battery hybrid energy storage system applied in electric vehicles are discussed.Then, according to the technical requirements on EVs in New Pure Electric Passenger Car Enterprise Management Regulations, this paper chooses a miniature pure electric vehicle and redesigns its powertrain, and builds the simulation models of the power battery, ultra-capacitor and bidirectional DC/DC converter. According to the working mode of the hybrid energy storage system, the power allocation strategy of the system is built by fuzzy control method.Finally, by redeveloping the electric vehicle simulation software ADVISOR, the simulation platform of a pure electric vehicle supplied with hybrid energy storage system is established. According to the analysis of simulation results, this paper is concluded as follows: the parameter matching in this paper has certain rationality, which can meet the vehicle performance; the power allocation strategy of hybrid energy storage system achieves the expected goals; with the access of the ultra-capacitor, the power battery discharge smoothly, and braking energy is mostly recycled by the ultra-capacitor, which avoids the impact on the power battery with large current during charge and discharge mode, resulting in improving the working condition of the power battery and then contributes to improve its cycle lifetime. At the same time, to solve the problems that the secondary development of ADVISOR in the present research of hybrid energy storage system is complex and needs large workload, this paper summarizes a way to redevelop ADVISOR accurately and quickly, which can provide conveniences for the related research work.