Electric vehicle regenerative braking system based on constant current control of composite power sources

Due to the characteristics of high power density existing in super capacitor, the defects of low power density in power battery can be remedied, by using super capacitor as the auxiliary power source of electric vehicle. electric vehicle regenerative braking system is acted as the research object, the mathematical models of electric vehicle regenerative braking system of composite power sources are established, consisting of the brushless dc motor, Buck-Boost DC-DC converter, super capacitor as well as controller. In order to validate the electric vehicle regenerative braking system model, the regenerative braking simulation test system is designed and developed, the small power brushless dc wheel motor drive system is used to simulate electric vehicle drive system, the flywheel moment of inertia is used to simulate electric vehicle inertia load. The mathematical models of regenerative braking system are calculated and experimental verified, the results show that the mathematical model established is accurate and effective. In order to maintain small braking torque fluctuation range during the braking process, constant current control strategy is employed to control the armature current. As simulation results and experiment data shows, electric vehicle composite power source, consisting of power battery and super capacitor, can effectively absorb the regenerative braking energy. By adopting the constant current control strategies, stable braking torque can be implemented in the process of braking, and higher energy recovery efficiency is realized. © 2013 Journal of Mechanical Engineering.