Chevrolet Bolt Electric Vehicle Model Validated with On-the-Road Data and Applied to Estimating the Benefits of a Multi-Speed Gearbox 2022-01-0678

This paper presents a model for predicting the energy consumption of a 2017 Chevrolet Bolt electric vehicle. The model is validated using 93 measured drive cycles covering in excess of 10,600 kilometres of driving and temperatures from −8 to 32 ^°C. The mechanical road load acting on the vehicle is calculated via ABC parameters from the publicly available US Environmental Protection Agency (EPA) Annual Certification Data database. The vehicle model includes wheel diameter, gear ratio, rated electric machine torque and power, 12V accessory load based off measurements, measured electric machine efficiency obtained from a publication from General Motors, and modelled inverter efficiency. Assumptions are made regarding gearbox losses as well. To ensure accuracy under real-world conditions, road grade, temperature effects, and heating and cooling energy are included as well. The model predicts an EPA range of 380 km, which is very close to the 383 km rating. Error is typically around ±10% for the experimental drive cycles used for validation. The presented modelling methodology can be applied to any production battery electric vehicle and used to predict the benefits of utilizing multi-speed gearboxes, wideband gap semiconductor inverters, different electric traction machine designs, and other vehicle design changes. The paper includes an extensive comparison of modelled versus measured results, as well as an analysis of the benefits of a multi-speed gearbox for the vehicle, showing an increase of range of 1.3% (5 km) with a two-speed gearbox.