Abstract: A regenerative braking energy management strategy for mild hybrid electric vehicles (HEVs) is proposed, whose optimal object is to maximize the braking energy recovery of battery under the precondition of satisfying braking regulation of ECE. Based on the generator efficiency map, the battery efficiency map and the engine drag torque map, the optimization model of braking force distribution of generator and brake system is build, and the regenerative braking energy management rules under different braking ratio are obtained for the mild HEVs with manual transmission and continuously variable transmission respectively. The simulations for the mild HEVs with three types of transmissions, i. e. single clutch–manual transmission, double clutches–manual transmission and continuously variable transmission, are finished under the NEDC cycle mode respectively, and the results indicate that the regenerative energy efficiency of mild HEVs with double clutches–manual transmission is the highest. The braking control test of the mild hybrid power train with manual transmission is carried out based on the rapid control prototyping technology of dSPACE.

Key words: Continuously variable transmission, Energy management strategy, Hybrid electric vehicles, Regenerative braking