Characterization and effectiveness of an ultracapacitor bank to enhance a battery electric vehicle energy storage system dynamics

In order to operate the supercapacitor as a peak power unit until the end of its lifetime in real applications, identifying the electrical characteristics and assessing the energy capacity are essential procedures. This paper introduces a brief design and implementation of a current controlled DC/DC buck converter in order to experimentally characterize the supercapacitor versus the applied voltage across its terminals. The effectiveness of the supercapacitor in a hybrid energy storage system combining a battery and a supercapacitor bank during regenerative braking is investigated in this paper. The battery over voltage and current gradient are investigated in case of hybridization with the supercapacitor module and when the battery is working alone. During the regenerative braking, it was found from the experimental results that the supercapacitor is effective with a percentage of 71.4% at the motor maximum speed and with a percentage 56% of the current sharing at 25% of the motor maximum speed.