Application of the Transmotor-Flywheel Technology to Mild Hybrid Powertrain for Fuel Economy Improvement

Previous research has used a flywheel connected to a dual-mechanical shaft electric machine named transmotor to improve energy efficiency and reduce electric power rating in a battery electric vehicle (BEV) powertrain. However, the effect of this transmotor-flywheel technology on a mild hybrid electric vehicle (HEV) powertrain has not been previously studied. This paper presents this study and optimizes the fuel economy using the dynamic programming (DP) algorithm. The optimal fuel economy of the proposed HEV powertrain is compared with that of the original mild HEV powertrain without this technology, during benchmark driving cycles. Results show that this technology can improve the fuel economy of the proposed powertrain with an electric drive which has notably smaller electric power rating than that of the original powertrain, leading to a reduction in costs.