A supervisory controller for a hybrid energy storage system with two propulsion machines in electric vehicles

Abstract

In this paper, a power split control strategy is proposed for an electric vehicle (EV) powertrain with two propulsion machines and a battery/ultra-capacitor (UC) hybrid energy storage system (HESS). Using this supervisory control strategy, the load power is effectively split between the two propulsion machines to obtain the highest powertrain efficiency in both propulsion and regenerative braking modes. In addition, in order to optimize the power split in HESS, a convex optimization problem is formulated to minimize the battery power magnitude and battery current variations. With the proposed supervisory control strategy, 10% improvement in the powertrain efficiency and 82% extension of the battery lifetime is expected.