An experimental and analytical study of the ultra-capacitor storage unit used in regenerative braking systems

Ultra-capacitor (UC) is a type of rechargeable energy storage unit used in different industrial applications. It has been utilised to transmit high current on acceleration and to accept regenerative braking energy on descending and braking in electric vehicles, and hybrid electric vehicle power applications. In this research, the UC has been tested in the laboratory and studied in the simulation with the aim to investigate a method for harvesting energy. Analysis of electricity generated from the braking process by rotating machinery has been carried out at a designed test rig with the prime objective of monitoring UC charging voltage at different states. The newly proposed modelling and algorithm consider the generator and the UC as two storage units having a capacitance and different voltage levels for dynamic charge transfer and the observation of voltage states for demanding applications. This method defines the generator variable charging behaviour, and the UC response shows an accurate simulation. (C) 2019 The Authors. Published by Elsevier Ltd.