Parallel Hybrid Vehicle Optimal Storage System

A paper reports the results of a Hybrid Diesel Vehicle Project focused on a parallel hybrid configuration suitable for diesel-powered, medium-sized, commercial vehicles commonly used for parcel delivery and shuttle buses, as the missions of these types of vehicles require frequent stops. During these stops, electric hybridization can effectively recover the vehicle’s kinetic energy during the deceleration, store it onboard, and then use that energy to assist in the subsequent acceleration.

This innovation is particularly useful with energy storage devices where the state of charge is readily determined by an easily measurable attribute. The ultracapacitor and pressurized hydraulic storage cylinder are good examples of this type. The state of charge, or energy level, is proportional to the voltage of the ultracapacitor and pressure of the hydraulic cylinder. The method is well suited to hybrid vehicle applications where the hybrid power is primarily used during acceleration and deceleration. This method can be executed with limited vehicle state information. Primarily, the only feedback required is the state of charge of the energy storage device, vehicle speed, and operator throttle request.

The Hybrid Booster Drive (HBD) control system has the potential to have similar benefits with modern diesel and non-diesel engines, and when applied to optimized drive trains. It has the potential to deliver equal or better performance than other systems, and may be produced at reduced cost and complexity. Test data are available that show the implementation of the invention during operation of two prototype hybrid electric vehicles.

This work was done by Aaron P. Bloomfield of Bowling Green State University, Electric Vehicle Institute, for Glenn Research Center.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steve Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-18289-1.