Application of fuzzy logic to control regenerative braking energy for hybrid electric vehicles

Abstract

Nowadays, hybrid electric vehicles (HEVs) have been speedily developed and deployed by automobile manufacturers to improve their fuel consumption and reduce their pollutant emissions. This remarkable success is thanks to flexible control strategies. These components such as internal combustion engines, motors/generators, batteries, and power-split devicesmight operate efficiently depending on the vehicle driving conditions. Every component always operates at its optimal area. However, to attain to perfection, researchers proposed various optimal control methods. Besides optimizing the control strategies of power flow for power-split HEV during traction, energy regeneration during braking is also an important technique. This paper focuses on regenerative braking in a power-split HEV system and specifically on how its control strategy can be formulated and optimized. The braking control strategy adopts a fuzzy logic approach to make the best compromise between mechanical braking torque and regenerative braking torque. An initial investigation of the vehicle dynamic behavior under braking conditions serves as the basis for the development of a control strategy for the best braking performance and maximum energy recovery. The implementation of the control strategy requires a fully integrated traction and braking control model. The power-split HEV model is built with Matlab/Simulink package and the simulation results show significant improvements in fuel consumption.