Electrification and Integration of Accessories on a Class-8 Tractor 2005-01-0016

This paper describes installation and testing of electrified engine accessories and fuel cell auxiliary power units for a Class-8 tractor. A 2.4 kW fuel cell APU (Auxiliary Power Unit) has been added to supply a 42 V power supply for electrification of air conditioning and water pump systems. A 42/12 V dual alternator was used to replace the OEM alternator to provide safety back-up in case of fuel cell failure. A QNX Real Time Operating System-based (RTOS) Rapid Prototype Electronic Control System (RPECS™), developed by Southwest Research Institute (SwRI™), is used for supervisory control and coordination between accessories and engine. A Controller Area Network (CAN) interface, from the engine Electronic Control Unit (ECU), and the RS232 interface, from the fuel cell controllers, provide system data and control for RPECS. Custom wiring to the hydrogen, water pump, and air conditioning systems also provide data to RPECS. The water pump system controller is autonomous. A driver touch screen graphical interface is linked to the RPECS for display and troubleshooting of the system. The RPECS controller also supports startup/shut down procedures, data logging, data backup and diagnostics.

Data analyses for a typical driving cycle with system level breakdown of energy usage and improvement in operating efficiency is provided. Operational strategy of fuel cells, air conditioning, engine mechanical fan and water pump are discussed. Engine efficiency changes are qualified. These are due to smarter cooling, minimizing fan operation, and optimization of a modulating water pump cooling system.

This work has been performed at SwRI on the SunLine Project, funded by US Army National Automotive Center (NAC).