Development of 80- and 100- Mile Work Day Cycles Representative of Commercial Pickup and Delivery Operation

When developing and designing new technology for integrated vehicle systems deployment, standard cycles have long existed for chassis dynamometer testing and tuning of the powertrain. However, to this day with recent developments and advancements in plug-in hybrid and battery electric vehicle technology, no true “work day” cycles exist with which to tune and measure energy storage control and thermal management systems. To address these issues and in support of development of a range-extended pickup and delivery Class 6 commercial vehicle, researchers at the National Renewable Energy Laboratory in collaboration with Cummins analyzed 78,000 days of operational data captured from more than 260 vehicles operating across the United States to characterize the typical daily performance requirements associated with Class 6 commercial pickup and delivery operation. In total, over 2.5 million miles of realworld vehicle operation were condensed into a pair of duty cycles, an 80-mile cycle and a 100-mile cycle representative of the daily operation of U.S. class 3-6 commercial pickup and delivery trucks. Using novel machine learning clustering methods combined with mileage-based weighting, these composite representative cycles correspond to 90th and 95th percentiles for daily vehicle miles traveled by the vehicles observed. In addition to including vehicle speed vs time drive cycles, in an effort to better represent the environmental factors encountered by pickup and delivery vehicles operating across the United States, a nationally representative grade profile and key status information were also appended to the speed vs. time profiles to produce a “work day” cycle that captures the effects of vehicle dynamics, geography, and driver behavior which can be used for future design, development, and validation of technology. Introduction Under DOE-FOA-0001349 FY15 Award for Mediumand Heavy-Duty Vehicle Powertrain Electrification, Cummins and PACCAR jointly proposed the development of a range-extending plug-in hybrid electric Class 6 pickup and delivery truck. The goal of this project is to demonstrate an electrified vehicle that would deliver a minimum of 50% reduction in fuel consumption across a range of representative drive cycles. In addition to achieving the 50% fuel reduction target, the vehicle also needs to demonstrate as good or better drivability and performance while still meeting emissions requirements when compared to existing conventionally fueled baseline vehicles. Most existing duty cycles used to test conventional internal combustion powered vehicles are of a limited time duration. For example, the Hybrid Truck Utility Forum Class 6 Pickup and Delivery cycle is slightly more than one hour. When testing a system using only fuel as its energy source, this is acceptable; a onehour duty cycle can be used to represent the vehicle operation for the entire work day (e.g., fuel consumption in the middle of the day is very similar to fuel consumption at the end of the day). However, with plug-in electric vehicles, the system (battery characteristics and thermal management systems) may operate differently throughout the work day (especially near the end of the day). For example, the available battery energy may be completely spent prior to the completion of the route. A short duty cycle cannot simply be extrapolated. Evaluating the vehicle over the entire work day also provides the ability to interject appropriate stops that are typical of the Class 6-7 pickup and delivery application. These stops can range from several minutes to much longer and can have significant thermal effect on the vehicle and powertrain systems. These stops may also have a large impact on overall duty cycle mileage (and other duty cycle characteristics such as average speed) as the stops may account for roughly half of the work day. As part of the research and development team, the National Renewable Energy Laboratory (NREL) was been NREL/CP-5400-70943. Posted with permission. Presented at WCX 18: SAE World Congress Experience, 10-12 April 2018, Detroit, Michigan.