Optimization of gear shifting strategy for hybrid electric vehicles on the process of braking

A new optimization method for gear shifting on single shaft hybrid electric vehicles is proposed to improve the braking performance. Three parameters （vehicle acceleration, motor torque and weight of vehicle) in objective function are determined to have influence on the process of braking. Optimal shifting velocity is found from the given parameters by Multi-Island Genetic Algorithm (MIGA) and values of objective function are compared to decide whether vehicle shifts or not. In the Chinese typical city cycle, the strategy appears to have less sum of braking pedal aperture on the process of braking and avoid the problem of shifting frequently by fuzzy control.