Modeling and Controls Development of 48V Mild Hybrid Electric Vehicles
Lee, S., J. Cherry, S. Michael, A. Neam, J. McDonald, AND K. Newman. Modeling and Controls Development of 48V Mild Hybrid Electric Vehicles. SAE Technical Paper Series. SAE International, Warrendale, PA, , 15, (2018). https://doi.org/10.4271/2018-01-0413
The purpose of this work was to develop a vehicle energy model capable of simulating regulatory drive cycle results for 48V Mild Hybrid Electric Vehicles (MHEV). An initial vehicle model was developed using commercial Gamma Technologies GT-DRIVE vehicle simulation software. Submodels were developed to represent the driver, thermal conditions, and vehicle road loads and MHEV subsystems such as the electric machine, battery, engine, transmission, and vehicle supervisory controls. The control strategies and modeling approach were validated via comparison of GT-DRIVE modeling runs to vehicle chassis dynamometer data. The modeled systems are now in the process of being ported form the GT-DRIVE platform into the EPA ALPHA vehicle model.
The Advanced Light-Duty Powertrain and Hybrid Analysis tool (ALPHA) was created by EPA to evaluate the Greenhouse Gas (GHG) emissions of Light-Duty (LD) vehicles. It is a physics-based, forward-looking, full vehicle computer simulator capable of analyzing various vehicle types combined with different powertrain technologies. The ALPHA desktop application was developed using MATLAB/Simulink. The ALPHA tool was used to evaluate technology effectiveness and off-cycle technologies such as air-conditioning, electrical load reduction technology and road load reduction technologies of conventional, non-hybrid vehicles for Midterm Evaluation of the 2017-2025 LD GHG rule by the U.S. Environmental Protection Agency (EPA) Office of Transportation and Air Quality (OTAQ). This paper presents controls development, modeling results, and model validation for simulations of a vehicle with a 48V Belt Integrated Starter Generator (BISG) mild hybrid electric vehicle and initial modeling results for a 48V inline on-axis P2-configuration mild hybrid electric vehicle. Both configurations were modeled with a Matlab/Simulink/Stateflow tool, which has been integrated into EPA’s ALPHA vehicle model, and was also used to model components within Gamma Technologies GT-DRIVE simulations. The mild hybrid electric vehicle model was validated using vehicle data obtained from Argonne National Laboratory (ANL) chassis dynamometer tests of a 2013 Chevrolet Malibu Eco 15kW 115V BISG mild hybrid electric vehicle. The simulated fuel economy, engine torque/speed, motor torque/speed, engine on-off controls, battery voltage, current, and State of Charge (SOC) were in good agreement with the vehicle test data on a number of drive schedules. The developed 48V mild hybrid electric vehicle model can be used to estimate the greenhouse gas emissions (GHG) and fuel economy of 48V mild hybrid electric vehicles over the regulatory drive cycles and to estimate off-cycle GHG emissions. The 48V mild hybrid electric vehicle model will be further validated with additional 48V mild hybrid electric vehicle test data in the future as more vehicle models become available. EPA has included 48V BISG mild hybrid electric vehicle technology in its assessment of CO2-reducing technologies available for compliance with U.S. GHG standards.
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