Evaluation strategy of regenerative braking energy for supercapacitor vehicle

•This paper proposes an evaluation strategy of regenerative braking energy for electric vehicle powered by supercapacitors.•The maximum efficiency of braking energy can be up to 88%.•The braking energy recovery efficiency of electric vehicles is greatly enhanced by supercapacitors.•The regenerative braking energy efficiency varies along with the driver behavior.•The brake pedal force is one of the important factors that impact the regenerative efficiency.

In order to improve the efficiency of energy conversion and increase the driving range of electric vehicles, the regenerative energy captured during braking process is stored in the energy storage devices and then will be re-used. Due to the high power density of supercapacitors, they are employed to withstand high current in the short time and essentially capture more regenerative energy. The measuring methods for regenerative energy should be investigated to estimate the energy conversion efficiency and performance of electric vehicles. Based on the analysis of the regenerative braking energy system of a supercapacitor vehicle, an evaluation system for energy recovery in the braking process is established using USB portable data-acquisition devices. Experiments under various braking conditions are carried out. The results verify the higher efficiency of energy regeneration system using supercapacitors and the effectiveness of the proposed measurement method. It is also demonstrated that the maximum regenerative energy conversion efficiency can reach to 88%.