Design and Implementation of a Belted Alternator Starter System for the OSU Ecocar 3 Vehicle THESIS
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Design and Implementation of a Belted Alternator Starter System for the OSU EcoCAR 3 Vehicle THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Dennis Ssebina Kibalama Graduate Program in Electrical and Computer Science The Ohio State University 2017 Master's Examination Committee: Dr. Giorgio Rizzoni, Advisor Dr. Levent Guvenc Dr. Shawn Midlam-Mohler Copyrighted by Dennis Ssebina Kibalama 2017 Abstract The transportation sector is a great contributor to overall energy consumption and emissions. Stringent regulations have been put in place to curb the emissions and regulate fuel consumption due to dependency on a finite resource, fossil fuels. This has driven OEMs to re-engineer the automotive powertrain which has led to a burst in production of PHEVs, HEVs and EVs. The U.S. D.O.E, General Motors, Argonne National Laboratory (ANL) and other industry sponsors have spearheaded (Advanced Vehicle Technology Competitions) AVTCs with a goal of training the next generation of automotive engineers by challenging collegiate teams to re-engineer stock vehicles to improve fuel consumption, reduce emissions while maintaining consumer acceptability. The latest in this AVTC series is the EcoCAR 3, a 4-year competition which challenges 16 North American university teams to re-engineer a 2016 Chevrolet Camaro into a HEV while maintaining the performance aspects of the iconic American car. The OSU EcoCAR 3 vehicle boasts a Parallel-series post transmission PHEV architecture designed by the team in Year 1 of the competition. To meet the team designed (Vehicle Technical Specification) VTS targets, the architecture includes a motor coupled to the engine, a Belted Alternator Starter (BAS) which performs engine start/stop, series operation, speed matching and torque assist. Due to the versatility of the component in ii realizing the VTS targets, this thesis sets to outline the design and validation work done with regards to the BAS system. The BAS system consists of the electric machine, the engine, belt transmission, inverter and battery pack. The thesis outlines the design metrics considered in the design of the BAS system ranging from electrical, performance, mechanical and thermal considerations. The BAS chosen is a sponsor donated component that wasn't supplied with an inverter solution. This thesis details the two inverter choices adopted over Years 2 – 3 of the competition and the control, calibration, validation, performance and packaging carried out to realize functionality of the BAS. To accurately model the dynamics of the BAS system during engine startup, a dynamic engine model is developed to model engine, BAS and belt transmission dynamics. The underlying assumptions made to develop an accurate representation of the dynamics while minimizing calibration efforts are also outlined. This model will be used in Year 4 for development and optimization of an engine start/stop controller. The thesis also analyses the two control methods adopted for engine start; an open loop controller and a closed loop controller and evaluates the performance of the controllers in terms of rise time, engine speed overshoot, maximum jerk and root mean square acceleration. This thesis encompasses the design and validation work done to move the BAS system development work from a component/subsystem level to vehicle/system level. This sets the team in a good position heading into Year 4 of the competition to implement engine start/stop functionality in the vehicle, optimize torque assist functionality and use the BAS for speed matching for faster shift times. iii Acknowledgments I am indebted to the entire support of the people at the OSU Center for Automotive Research. I would like to thank Dr. Giorgio Rizzoni and Dr. Shawn Midlam-Mohler for not only the opportunity to work with the OSU EcoCAR team but also their guidance and tutelage as I pursued graduate studies; their ideas, thought processes and drive were instrumental in my time at The Ohio State University. I'd like to acknowledge my fellow EcoCAR team members who were very resourceful and hardworking individuals dedicated to applying their engineering skills and knowledge to solve engineering challenges and achieve a well-engineered Camaro. Shout out to Aditya Modak, Andrew Huster, Andrew Johnson, Arjun Khanna, Brandon Bishop, Greg Jankord, Kristina Kuwabara, Nick Tomczack, Simon Trask and Wilson Perez. A special shout out to Andrew Huster and his family for making my experience in a new country memorable. You surely made Ohio a home away from home. I am indebted to Kiira Motors Corporation for facilitating my pursuit for higher education; none of this would have been possible without them. I am thankful for my family and friends in Uganda that have supported me throughout my pursuit of graduate studies. Finally, I'm thankful to the EcoCAR organizers and sponsors that make this an invaluable learning experience for everyone involved with AVTCs. iv Vita October 24, 1990 ............................................Born – Kampala, Uganda 2008................................................................Makerere College School, Uganda June 2013 ......................................................B.S. Electrical Engineering, Makerere University, Uganda August 2014 to present .................................Graduate Research Associate, Department of Electrical and Computer Engineering, The Ohio State University. Publications D. Kibalama, A. Huster, A. Khanna, A. Modak, M. Yasko, G. Jankord and S. Midlam- Mohler. “Testing and Validation of a Belted Alternator Starter System for a Post- Transmission Parallel PHEV for the EcoCAR 3 Competition”. SAE Technical Paper, 2017-01-1263, Oct. 2016. Fields of Study Major Field: Electrical and Computer Engineering v Table of Contents Abstract ............................................................................................................................... ii Acknowledgments .............................................................................................................. iv Vita ...................................................................................................................................... v Publications ......................................................................................................................... v Fields of Study .................................................................................................................... v Table of Contents ............................................................................................................... vi List of Tables ..................................................................................................................... xi List of Figures ................................................................................................................... xii List of Acronyms .............................................................................................................. xv Chapter 1: Introduction ....................................................................................................... 1 1.1. Energy Trends Analysis and Motivation .............................................................. 1 1.2. AVTCs & The EcoCAR 3 Competition ............................................................... 3 1.3. Vehicle Architecture ............................................................................................ 5 1.4. Vehicle Technical Specifications ......................................................................... 6 1.5. Objectives ............................................................................................................. 7 1.6. Thesis Overview ................................................................................................... 7 vi Chapter 2: Literature Review .............................................................................................. 9 2.1. Introduction .......................................................................................................... 9 2.2. Drivetrain Electrification ...................................................................................... 9 2.2.1. Hybrid Electric Vehicles (HEVs) ............................................................... 10 2.2.2. Plugin Hybrid Electric Vehicles (PHEVs) .................................................. 11 2.2.3. HEV & PHEV Configurations .................................................................... 12 2.2.4. Degrees of Hybridization ............................................................................ 15 2.3. Inverter Control .................................................................................................. 16 2.4. Drive Quality and NVH ..................................................................................... 17 2.4.1. Engine start/stop times ................................................................................ 18 2.4.2. Jerk .............................................................................................................. 18 2.4.3. Root Mean Square Acceleration ................................................................. 18 2.4.4. Vibration Dose Value (VDV) ..................................................................... 19 Chapter 3: System Design Considerations ........................................................................ 20 3.1. Introduction .......................................................................................................