A Design Procedure for Alternative Energy Storage Systems for Hybrid Vehicles 2011-24-0079
Although electrochemical batteries are the mainstream for hybrid vehicle energy storage, there is continuing interest in alternative storage technologies. Alternative energy storage systems (AESS), in the form of mechanical flywheels or hydraulic accumulators, offer the potential to reduce the vehicle costs, compared to the use of electrochemical batteries. In order to maximize the benefits of mechanical or hydraulic energy storage, the system design must maximize the energy recuperation through regenerative braking and the use of the energy stored with high roundtrip efficiency, while minimizing system volume, weight and cost.
This paper presents a design procedure for alternative energy storage systems for mild-hybrid vehicles, considering parallel hybrid architecture. The procedure is applied with focus on the definition of design parameters and attributes for a hydraulic AESS with high pressure accumulator. The design methodology is based on a definition of targets and constraints for the AESS, obtained from a statistical analysis of the energy and power requirements of a variety of drive cycles.
The design obtained was then implemented in an energy-based simulator over a selected variety of driving cycles. A comparison of performance (including power, energy and roundtrip efficiency) is conducted to evaluate the benefits provided by the hydraulic ESS for energy recuperation while comparing different design methods.