Regenerative braking control of multi-step series hybrid energy storage system with energy constraint for practical operation

Regenerative braking plays an important role in improving the driving range of electric vehicles. To achieve accurate and efficient braking deceleration control, this research focuses on energy recovery process with ultracapacitor (UC). According to the statistical analysis results of the characteristics for typical operation, a multi-step series hybrid energy storage system(M-SHESS) is constructed to realize the energy recovery with grading in braking process. To explore the accurate measurement of braking deceleration without the vehicle speed sensor in the braking force control, the relationship between the energy recovered by UC modules and the braking deceleration during the braking energy recovery is analyzed, and the deceleration control method with energy constraint for braking force is proposed. Results show that M-SHESS can be applicable for the energy recovery process on different operation, and can effectively improve the efficiency of energy recovery. Moreover, the deceleration control method based on energy constraint can meet the vehicle braking requirement. The research for M-SHESS provides new ideas and approaches for the development of electric vehicles and fuel cell vehicles.