Design and Application of Flywheel–Lithium Battery Composite Energy System for Electric Vehicles
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Binbin Sun , Mengxue Xie , Bo Li , Pengwei Wang , Song Gao |
School of Transportation and Vehicle Engineering , Shandong University of Technology |
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ABSTRACT |
For diff erent types of electric vehicles, improving the effi ciency of on-board energy utilization to extend the range of vehicle
is essential. Aiming at the effi ciency reduction of lithium battery system caused by large current fl uctuations due to sudden
load change of vehicle, this paper investigates a composite energy system of fl ywheel–lithium battery. First, according to the
design requirements of vehicle performance, the essential parameters of the hybrid energy storage system are designed using
CPE function. Then, based on the vehicle dynamics and operating principle of the hybrid energy system, a mathematical
model for performance analysis of the hybrid energy electric vehicle is established. Finally, energy management strategy for
the hybrid energy system is designed with the use of wavelet algorithm. Research results show signifi cant improvement of the
storage system effi ciency. Specially, compared with the original scheme, owing to the fl ywheel battery, the maximum current
and discharge rate of the lithium battery are reduced by 6.55% and 4.76% under WLTC working condition. Meanwhile, the
average current is decreased by 14.93%. Furthermore, the average effi ciency of lithium battery is improved by 3.07%. The
overall effi ciency of energy storage system is increased by 2.01%. |
Key Words:
Electric vehicle · Flywheel battery · Composite energy system · Energy management
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