Embedded Control Scheme of Stand-Alone Regenerative Braking System using Supercapacitors

Abstract

The concept of Energy Storage System (ESS) in Electric Vehicle (EV) is the most important challenging part of EV design. Batteries are the main electric ESS which has mostly used for supplying the energy requests and charging the Batteries is a major concern. Supercapacitors based on their specifications are effective for this role. Very high power delivery and fast charging are the most famous parameters of supercapacitors which make them suitable for EVs. This paper describes a novel scheme to manage multiple supercapacitor banks which will assist in continuous storing of braking energy and expend on to the load once fully charged. In the present design, the system monitors the State-Of-Charge (SOC) of each supercapacitor in the bank during each charge/discharge sequence for efficient utilization of produced energy via braking. Supercapacitor bank is designed by connecting the supercapacitor cells in series to increase the rated voltage. Nevertheless, each supercapacitor bank may suffer from the unstable charging consequence due to its inherent characteristic between each supercapacitor in the bank even though all these supercapacitors having the same specification. It is imperative to design a balancing circuit to evenly distribute the stored energy failing which the imbalance will cause some supercapacitors in the bank to reach the overcharging state. The present design prevents the supercapacitor bank from unwanted overcharging and helps protecting other supercapacitors in the bank itself. In this paper, we present a new control scheme which controls and monitors charge/discharge mechanism of supercapacitor bank with a view to incorporate the balancing circuit design for regenerative braking mechanism developed as part of the work.