Reducing the Variability of Hybrid Electric Vehicle Fuel Economy in the Real World

Apart from improving the fuel economy, a reduction in the variability of the fuel economy is also of significant importance for hybrid electric vehicles. Previously, research on how to optimise the sizes of the powertrain components of hybrid electric vehicles has generally focused on improving the fuel economy over a given driving pattern. The variability of the fuel economy over a realistic range of driving patterns has generally been overlooked, and this can mean that the fuel economy benefits of hybrid electric vehicles are not consistently realised in real-world usage. In a recent study, a new methodology for design optimisation of the powertrain components of hybrid electric vehicles was proposed for the reduction in the variability of the fuel economy due to variation in the driving patterns, but the methodology needs to be validated in real-world usage for practical applicability. In this paper, the methodology is validated in real-world driving conditions. This paper investigated the methodology for 10 real-world driving patterns generated by 10 different drivers over a predefined route consisting of urban and highway driving. The study was carried out using a simulation model of a Toyota Prius hybrid electric vehicle which was considered as the benchmark vehicle. The design produced by the methodology reduced the variability of the fuel economy by 5.3% without reducing the average fuel economy compared with the Toyota Prius over the 10 real-world driving patterns. This demonstrates that the methodology described is applicable to real-world usage.