Abstract
Hybrid power systems, formed by combining high-energy-density batteries and high-power-density ultracapacitors in appropriate ways, provide high-performance and high-efficiency power systems for electric vehicle applications. This paper first establishes dynamic models for the ultracapacitor, the battery and a passive hybrid power system, and then based on the dynamic models a comparative simulation between a battery only power system and the proposed hybrid power system was done under the UDDS (Urban Dynamometer Driving Schedule). The simulation results showed that the hybrid power system could greatly optimize and improve the efficiency of the batteries and their dynamic current was also decreased due to the participation of the ultracapacitors, which would have a good influence on batteries’ cycle life. Finally, the parameter matching for the passive hybrid power system was studied by simulation and comparisons.
Highlights
With the appearance of 89 kinds of new-energy vehicles in the 2010 Beijing Auto Show, various types of Electric Vehicles (EVs), like pure electric vehicles, hybrid electric vehicles and fuel cell electric vehicles, have begun to appear on the market [1,2]
Energies 2010, 3 energy storage system of EVs [3], but when a longer purely electric driving range, higher acceleration rates, and higher power-assisted performance are required simultaneously, as in plug-in hybrid electric vehicles, it is hard for a battery-only power system to meet these demands
Is more than 100 s and at 2 C it is more than 30 s, while for the hybrid power system, the charging current of battery pack is less than 0.33 C, and the braking energy is absorbed by the ultracapacitor pack, which results in much higher efficiency, the battery pack’s working condition is greatly optimized
Summary
With the appearance of 89 kinds of new-energy vehicles in the 2010 Beijing Auto Show, various types of Electric Vehicles (EVs), like pure electric vehicles, hybrid electric vehicles and fuel cell electric vehicles, have begun to appear on the market [1,2]. One solution is to select more costly larger capacity batteries, which would increase the vehicle weight and decrease the vehicle economy Another solution is to maintain the original battery capacity and to overcharge or overdischarge the battery, which would decrease its lifespan and make it work at lower efficiency. This dilemma suggests combining together batteries and ultracapacitors to form hybrid power systems as a promising solution to these problems because the ultracapacitor has a higher specific power and much longer lifespan than a battery, despite the fact that its energy density is much smaller than that of a battery [4]. This paper mainly discusses the passive hybrid power system to check its advantages and find a reasonable way to match its parameters
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