Implementing and testing the effects of road grade in the drive cycles for Malta

Abstract

Typical drive cycles such as the New European Drive Cycle (NEDC) and Worldwide Harmonised Light Vehicle Test Procedure (WLTP) typically simulate driving conditions 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 or the brakes. This project focused on implementing and testing the effects of road grade on vehicle performance (fuel consumption and CO2 emissions), through the use of a chassis dynamometer, using drive cycles obtained from the Maltese roads. The uphill grade was simulated by using an eddy current absorber which is in-built with the chassis dynamometer setup but is typically used to create loads during vehicle power tests. An electric motor was selected and implemented with the chassis dynamometer setup to simulate downhill grades. A LabVIEW program was developed to control the uphill and the downhill grades during the drive cycle testing which replaced the DynoMax software, generally used for power testing and not drive cycles. Two different vehicles were used during drive cycles testing, a 2019 Dacia Sandero Stepway and a 2017 Nissan Leaf to analyse the effects of road grade for both an internal combustion engine and an electric vehicle. The effects of grade in the drive cycles were analysed with respect to the fuel consumption and CO2 emissions for the Dacia Stepway and for vehicle power, energy consumption and charge level for the Nissan Leaf. The drive cycle tests were compared to the real-world data with respect to fuel consumption to check the accuracy of the LabVIEW program developed. The drive cycle tests were also compared to the DynoMax software in relation to the fuel consumption to cross-check the accuracy of the LabVIEW program. The LabVIEW program resulted in a higher fuel consumption than the real-world and dynamometer tests by the DynoMax software which was due to an offset resulting in a higher load being input by the eddy current. The drive cycle tests indicated that road inclination has a rather high impact on fuel consumption and emissions.