Hil test bench for development of hcng flex-fuel sensor and control strategy for a series HEV APU

This paper describes a hardware-in-The-loop (HIL) approach to develop a prototype Time of Flight (ToF) ultrasonic sensor which measures time varying ratios in hydrogen and natural gas (HCNG) fuel blends for real time engine control. The initial application envisioned for this sensor is for series hybrid electric vehicles (Series HEV) within auxiliary power units (APU) consisting of a relatively small IC engine and generator outputting near constant power to extend battery range between charges. The ultrasonic ToF sensor and control system enables the engine to start and run at low emissions under time varying HCNG blend ratios by adjusting engine fuel injector rate and ignition timing. This sensor thereby enables engine operation from a single gas storage tank compatible with both hydrogen and natural gas fueling stations. This "Flex-HCNG"APU could then be offered as optional equipment on pluggable electric vehicles already offering gasoline APUs. From knowledge gained on this small APU, the sensor could be further developed to support conventional car and heavy truck applications. Environmental benefits of implementing a Flex-HCNG system would include increased demand for electrified vehicles, greater use of alternative fuels including natural gas and hydrogen and increased deployment of their fueling infrastructure.