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Efficient Electro-Thermal Model for Lithium Iron Phosphate Batteries

University of Waterloo-Manoj Mathew, Mehrdad Mastali, John Catton, Ehsan Samadani, Michael Fowler
Published 2018-04-03 by SAE International in United States
The development of a comprehensive battery simulator is essential for future improvements in the durability, performance and service life of lithium-ion batteries. Although simulations can never replace actual experimental data, they can still be used to provide valuable insights into the performance of the battery, especially under different operating conditions. In addition, a single-cell model can be easily extended to the pack level and can be used in the optimization of a battery pack. The first step in building a simulator is to create a model that can effectively capture both the voltage response and thermal behavior of the battery. Since these effects are coupled together, creating a robust simulator requires modeling both components. This paper will develop a battery simulator, where the entire battery model will be composed of four smaller submodels: a heat generation model, a thermal model, a battery parameter model and a voltage response model. The paper will provide a brief description on each of these four sub-models and how they are correlated with each other. In addition, this work will…
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Degradation Testing and Modeling of 200 Ah LiFePO4 Battery

University of Waterloo-Satyam Panchal, Mahir Rashid, Frank Long, Manoj Mathew, Roydon Fraser, Michael Fowler
Published 2018-04-03 by SAE International in United States
In this paper, a degradation testing of a lithium-ion battery used for an electric vehicle (EV) is performed and the capacity fade is measured over 400 cycles. For this, a 200 Ah LiFePO4 battery cell is tested under ambient temperature conditions with charge-discharge cycles at rate of 1C (constant current). Additionally, individual cell characterization is conducted using a C/25 (0.8A) charge-discharge cycle and hybrid pulse power characterization (HPPC). Later, the Thevenin battery model was constructed in MATLAB along with an empirical degradation model and validated in terms of voltage for all cycles. It is also found that the presented model closely estimated the profiles observed in the experimental data. Data collected from the experimental results showed that a capacity fade occurred over the 400 cycles and the discharge capacity at the end of 400th cycle is found to be 137.73 Ah. The error between model/experiments is found to be less than 3.5% for all cycles.
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Measurement of Temperature Gradient (dT/dy) and Temperature Response (dT/dt) of a Prismatic Lithium-Ion Pouch Cell with LiFePO4 Cathode Material

University of Waterloo-Satyam Panchal, Scott Mathewson, Roydon Fraser, Richard Culham, Michael Fowler
Published 2017-03-28 by SAE International in United States
Lithium-ion batteries, which are nowadays common in laptops, cell phones, toys, and other portable electronic devices, are also viewed as a most promising advanced technology for electric and hybrid electric vehicles (EVs and HEVs), but battery manufacturers and automakers must understand the performance of these batteries when they are scaled up to the large sizes needed for the propulsion of the vehicle. In addition, accurate thermo-physical property input is crucial to thermal modeling. Therefore, a designer must study the thermal characteristics of batteries for improvement in the design of a thermal management system and also for thermal modeling. This work presents a purely experimental thermal characterization in terms of measurement of the temperature gradient and temperature response of a lithium-ion battery utilizing a promising electrode material, LiFePO4, in a prismatic pouch configuration. The experiment was designed to obtain thermal images of the LiFePO4 cell to qualitatively evaluate the thermal behaviour and temperature distribution with IR (Infrared Radiation) imaging technique at different discharge rates of 2C, 3C, and 4C. A “FLIR System” Therma CAM model S60…
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Extended Range Electric Vehicle Powertrain Simulation, and Comparison with Consideration of Fuel Cell and Metal-Air Battery

University of Waterloo-John Catton, Caixia Wang, Steven Sherman, Michael Fowler, Roydon Fraser
Published 2017-03-28 by SAE International in United States
The automobile industry has been undergoing a transition from fossil fuels to a low emission platform due to stricter environmental policies and energy security considerations. Electric vehicles, powered by lithium-ion batteries, have started to attain a noticeable market share recently due to their stable performance and maturity as a technology. However, electric vehicles continue to suffer from two disadvantages that have limited widespread adoption: charging time and energy density. To mitigate these challenges, vehicle Original Equipment Manufacturers (OEMs) have developed different vehicle architectures to extend the vehicle range.This work seeks to compare various powertrains, including: combined power battery electric vehicles (BEV) (zinc-air and lithium-ion battery), zero emission fuel cell vehicles (FCV)), conventional gasoline powered vehicles (baseline internal combustion vehicle), and ICE engine extended range hybrid electric vehicle. The parameters of comparison are: energy consumption, range, life cycle and tailpipe emissions, cost, and customer acceptance. A unique zinc-air battery model was developed using the vehicle modelling software to perform the analysis, with consideration of research data, current market status, and controls logic of the dual energy…
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Control Analysis for Efficiency Optimization of a High Performance Hybrid Electric Vehicle with Both Pre and Post Transmission Motors

University of Waterloo-Patrick Ellsworth, Roydon Fraser, Michael Fowler, Daniel VanLanen, Ben Gaffney, Caixia Wang, Trong Shen, Wenhao Wu, Paul McInnis
Published 2016-04-05 by SAE International in United States
The drive to improve and optimize hybrid vehicle performance is increasing with the growth of the market. With this market growth, the automotive industry has recognized a need to train and educate the next generation of engineers in hybrid vehicle design. The University of Waterloo Alternative Fuels Team (UWAFT), as part of the EcoCAR 3 competition, has developed a control strategy for a novel parallel-split hybrid architecture. This architecture features an engine, transmission and two electric motors; one pre-transmission motor and one post-transmission motor.The control strategy operates these powertrain components in a series, parallel, and all electric power flow, switching between these strategies to optimize the energy efficiency of the vehicle. Control strategies for these three power flows are compared through optimization of efficiencies within the powertrain. The resulting control strategy optimizations used by the team have increased the vehicle’s charge depleting range by 27.7 %., while decreasing energy consumption by 13.8 %. Additionally it produced a 30.5 % increase in miles per gallon gasoline equivalent in charge sustaining mode, increasing total range by 30.2%.
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Three-Dimensional Electrochemical Analysis of a Graphite/LiFePO4 Li-Ion Cell to Improve Its Durability

University of Akron-Siamak Farhad
University of Waterloo-Mehrdad Mastali Majdabadi Kohneh, Ehsan Samadani, Roydon Fraser, Michael Fowler
Published 2015-04-14 by SAE International in United States
Lithium-ion batteries (LIBs) are one of the best candidates as energy storage systems for automobile applications due to their high power and energy densities. However, durability in comparison to other battery chemistries continues to be a key factor in prevention of wide scale adoption by the automotive industry. In order to design more-durable, longer-life, batteries, reliable and predictive battery models are required. In this paper, an effective model for simulating full-size LIBs is employed that can predict the operating voltage of the cell and the distribution of variables such as electrochemical current generation and battery state of charge (SOC). This predictive ability is used to examine the effect of parameters such as current collector thickness and tab location for the purpose of reducing non-uniform voltage and current distribution in the cell. It is identified that reducing the non-uniformities can reduce the ageing effects and increase the battery durability. Finally, it is observed that simply changing tab locations can change the degree of non-uniformity in electrochemical current generation from a max-min variation of 10 % to…
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Thermal Management of Lithium-Ion Pouch Cell with Indirect Liquid Cooling using Dual Cold Plates Approach

SAE International Journal of Alternative Powertrains

University of Waterloo-Satyam Panchal, Scott Mathewson, Roydon Fraser, Richard Culham, Michael Fowler
  • Journal Article
  • 2015-01-1184
Published 2015-04-14 by SAE International in United States
The performance, life cycle cost, and safety of electric and hybrid electric vehicles (EVs and HEVs) depend strongly on their energy storage system. Advanced batteries such as lithium-ion (Li-ion) polymer batteries are quite viable options for storing energy in EVs and HEVs. In addition, thermal management is essential for achieving the desired performance and life cycle from a particular battery. Therefore, to design a thermal management system, a designer must study the thermal characteristics of batteries. The thermal characteristics that are needed include the surface temperature distribution, heat flux, and the heat generation from batteries under various charge/discharge profiles. Therefore, in the first part of the research, surface temperature distribution from a lithium-ion pouch cell (20Ah capacity) is studied under different discharge rates of 1C, 2C, 3C, and 4C. In the second part of the research, the total heat generation from a particular battery is obtained under different discharge rates (1C, 2C, 3C, and 4C) and different boundary conditions (cooling bath temperature of 5°C, 15°C, 25°C, and 35°C). In the third part of the research,…
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Experimental Measurements of Thermal Characteristics of LiFePO4 Battery

University of Waterloo-Satyam Panchal, Scott Mathewson, Roydon Fraser, Richard Culham, Michael Fowler
Published 2015-04-14 by SAE International in United States
A major challenge in the development of the next generation electric and hybrid electric vehicle (EV and HEV) technology is the control and management of heat generation and operating temperatures. Vehicle performance, reliability and ultimately consumer market adoption are integrally dependent on successful battery thermal management designs. In addition to this, crucial to thermal modeling is accurate thermo-physical property input. Therefore, to design a thermal management system and for thermal modeling, a designer must study the thermal characteristics of batteries. This work presents a purely experimental thermal characterization of thermo-physical properties of a lithium-ion battery utilizing a promising electrode material, LiFePO4, in a prismatic pouch configuration. In this research, the thermal resistance and corresponding thermal conductivity of prismatic battery materials is evaluated. The experiment was designed to measure the thermal conductivity of both the individual electrode layers, and the overall thermal resistance of the sealed prismatic structure. For this experiment, the first step was battery dissection, the second step was sample preparation and the third step was the measurement of thermal resistance. Thermal resistance measurements…
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Internal Resistance Optimization Utilizing “Just in Time” Control

University Of Waterloo-Patrick Ellsworth, William Scott, Michael Fowler, Roydon Fraser, Ben Gaffney, Daniel VanLanen
Published 2015-04-14 by SAE International in United States
Inspection of cell internal resistance (Rint) derived by the hybrid pulse power characterization (HPPC) tests indicates that Rint is a function of relative capacity (state of charge, or SOC), thus some SOC ranges are more efficient than others. Therefore energy losses can be minimized by placing charge sustaining operation in a more efficient SOC range. This creates three operational stages; the initial charge depleting stage to an efficient SOC, a charge sustaining stage until a recharge station is within reach, and a final charge depleting stage until arrival.When coupled with a known drive distance, this three segment Internal Resistance Based (IRB) control strategy increases the extended range electric vehicle (EREV) net battery efficiency from 96.8 to 97.3 % with an associated 14 % decrease in energy losses across the urban domestic drive schedule. Indirect benefits include an increased active SOC range, decreased urban emissions, and decreased waste heat generation, meeting the goals of Advanced Vehicle Technology Competitions.
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Modeling and Evaluation of Li-Ion Battery Performance Based on the Electric Vehicle Field Tests

University of Waterloo-Ehsan Samadani, Siamak Farhad, Satyam Panchal, Roydon Fraser, Michael Fowler
Published 2014-04-01 by SAE International in United States
In this paper, initial results of Li-ion battery performance characterization through field tests are presented. A fully electrified Ford Escape that is equipped by three Li-ion battery packs (LiFeMnPO4) including an overall 20 modules in series is employed. The vehicle is in daily operation and data of driving including the powertrain and drive cycles as well as the charging data are being transferred through CAN bus to a data logger installed in the vehicle. A model of the vehicle is developed in the Powertrain System Analysis Toolkit (PSAT) software based on the available technical specification of the vehicle components. In this model, a simple resistive element in series with a voltage source represents the battery. Battery open circuit voltage (OCV) and internal resistance in charge and discharge mode are estimated as a function of the state of charge (SOC) from the collected test data. It is shown that although the OCV should be measured under no-load condition, still it can be estimated with an acceptable accuracy (∼5%) from the driving data. Afterwards, performance of the…
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