An Adaptive Power-Split Strategy for Battery–Supercapacitor Powertrain—Design, Simulation, and Experiment

Electric vehicles (EVs) adopting both batteries and supercapacitors have attracted a significant amount of attention in research communities due to their unique power-sharing capabilities. A hybrid energy storage system (HESS) can effectively reduce power stress that would, otherwise, be applied to batteries alone, and whose weight and size is still a common concern when competing against conventional internal-combustion-engine-powered cars. In this paper, a high-level algorithm is developed to adaptively split the load between two sources for an EV adopting HESS under real-life load fluctuations. A converter—supercapacitor pack (SP) coupled HESS upon which such an algorithm is deployed on, is proposed to divert excess power into the SP via a smart power converter, which is located in between in order to regulate both behaviors. A power-split strategy is designed to track real-time load profiles and determine one important variable: the cutoff frequency. As a consequence, relatively higher frequency portion of the load power gets channeled to the SP, and the remaining less-varying power demand is sent to the BP based on the fundamental energy-balancing equation. A simplified HESS model is developed in MATLAB, and the real-time power-split algorithm is coded using Labview and verified on a test rig. Both simulation and experimental results prove its effectiveness in coping with even the harshest driving scenarios in real life.