Implementing of downhill road grade on chassis dynamometer for vehicle drive cycles testing

Typical drive cycles such as the New European Drive Cycle (NEDC) are typically simulating driving condition on flat roads. However, driving conditions in many regions of the world have quite demanding uphill and downhill conditions which greatly influence the demand on the engine and or brakes. This paper details the implementation of drive cycles with grades (both uphill and downhill) that better represent driving conditions in Malta. It was found that road inclination has a rather high impact on fuel consumption and emissions. Uphill driving required a bigger demand from the engine which is readily achieved by the chassis dynamometer braking capability. On the other hand, downhill driving emulation on the chassis dynamometer required motoring of the roller (and vehicle) and thus an electrically powered motor was utilized. The motor sizing, installation and LabVIEW programming required for this downhill emulation on an eddy current chassis dynamometer is detailed.