AMESim-Based Simulation Study On Parallel Hydraulic Hybrid Brake Energy Recovery System

In recent years there has been a thrust toward improving the fuel and energyefficiencies of passenger and off-road vehicles,as well as construction andagricultural machinery,driven by rising fuel costs and stricter emissionlaws.Research into these systems has involved operation points through powermanagement,as well as transmission mechanisms for recovery and capture ofenergy.Electric hybrids that use batteries and capacitors for energy capture andstorage,as well as hydraulic hybrid mobile machines that use accumulators for energystorage have been studied toward this end.Hybrid vehicles have become a viable solution to address the pressing needs ofenergy efficiency and engine emissions regulation in the near future.Hydraulic hybridtechnology is particularly suited for applications with duty cycles that require highpower and make frequent stops.The applications range from on-highway,such as citybus,parcel delivery and refuse trucks,to off-highway,such as constructions machinesand military vehicles.The hydraulic hybrid power-train technology is highlysophisticated and involves significant interaction between the engine,the hybridsystem and the vehicle.This requires optimal design of the hybrid to maximize thefuel savings.A computer simulation model of hybrid vehicle provides an efficient andcost-effective means to accelerate the development of the system design and energymanagement strategies.1. This paper summarizes the research activity performed in order to investigateconventional (electrical)&nonconventional (mechanical, hydraulic) hybrid systemsand their impact on the vehicle fuel economy while applying an optimizedcycle-independent control strategy.2. In order to perform the analysis hydraulic hybrid brake energy recovery system, AMESim R9(Advanced Modeling Environment for Simulations ofengineering systems) has been used as a common platform. AMESim is a modelbased software tool which offers a straightforward simulation of longitudinal vehicledynamic with special considerations on the driveline.3. The high-pressure accumulator stores hydraulic energy by compressing anitrogen gas-filled bladder inside a composite shell vessel. The gas compression wasmodeled as a polytrophic process using ideal gas and oil across the bladder material.4. Modeling of traditional city bus, torque coupling hydraulic energy recoverysystem and new hybrid city bus.The model was validated by performing drive cyclesimulations using the simulation framework, comparing the time traces of key systemvariables and running on the identical drive cycle.5. The component models were validated using experimental data provided bythe manufacturer (for hydraulic pump/motors, accumulator components and thediesel engine).