Maximisation of brake energy regeneration in a hybrid electric parallel car

This paper deals with the effective brake energy regeneration of parallel hybrid electric vehicles. A computational procedure to maximise the regenerated brake energy during braking is presented. Mathematical modelling, optimisation and computer simulation are essential tools. In addition to the computational procedure, an extensive sensitivity analysis is carried out on a medium-size car. The relation between the regenerated brake energy and the following properties are surveyed: rear and front electric machine efficiency; vehicle stability restriction; ICE drag torque; brake system characteristic; battery power; transmission ratios and battery resistance. Two driving cycles are evaluated: SFTP SCO3 includes more aggressive decelerations than the other cycle, NEDC. By switching between front-wheel and all-wheel drive and changing clutch arrangements, four different powertrain configurations are derived. All previously presented properties are analysed for each driving cycle and powertrain configuration. The results show, for example, that electric all-wheel drives tend to regenerate more brake energy compared with front-wheel drives in aggressive driving cycles.