Integrated Modeling Approach of an Electric Vehicle HVBattery for Optimizing the Energy Consumption Dvorak D., Simic D., Bäuml, T., Kapeller, H. AIT Austrian Institute of Technology GmbH
Agenda Introduction - Modeling and Simulation Practical Example Solution Approach Implementation Simulation and Results Discussion Conclusion and Outlook
Introduction - Modeling and Simulation Modeling and simulation are commonly used tools in the automotive sector Investigating the operating behavior of physical systems Analyzing different application scenarios and environmental conditions Simulations eliminate the need to perform protracted real-life tests
In the field of electric vehicles: energy efficiency is one of the main topics Target: improve maximum range Reduce energy consumption of auxiliary components
Development and simulation of an electric vehicle traction battery model Focus on thermal model and cooling circuit Modeling based on practical example Analyze the energy consumption required for keeping cell temperatures within a specific range
Practical Example Off-the-shelf electric vehicle
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AIT_Dvorak_ThermalBattery.nb
Battery stack consisting of 88 interconnected cells Cell temperature must not exceed a critical temperature level during operation Consider cooling circuit and strategy During load cycle Under specific ambient conditions
No general solution Determine level of abstraction Need proper simulation tool and model
Simulation Language and Tool Modelica Modern object-oriented modeling language Modeling complex multiphysical systems Algebraic or ordinary differential equations can be used Wolfram System Modeler Simulation tool GUI for Modelica
Solution Approach Thermal model of the battery system Cooling system model including cooling strategy SmartCooling library: Modeling and simulation of cooling circuits especially for automotive applications in Modelica Conductive heat transfer in pipes Prescribed mass flow, pressure and volume flow Pump and fan models ...
AIT_Dvorak_ThermalBattery.nb
Battery Model Concept Simplified electric model: 88 cells connected in series Focus on thermal model including cooling circuit Air cooling flow between and above the cells Overview of the chosen HV-battery including cooling concept:
Implementation - Electric Model Simplified electric loss model: i2 × R Constant internal resistance Interface to thermal model: thermal connector Current-profile over time (FTP72) electric losses heat flow
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AIT_Dvorak_ThermalBattery.nb
Implementation - Thermal Model Cell model: Heat capacity Thermal conductance to surfaces Stack model: Spatial cell interconnection Cooling circuit System model:
Implementation - Thermal Model Subsystem model:
AIT_Dvorak_ThermalBattery.nb
Implementation - Thermal Model Subsystem model - detail view:
Simulation and Results Discussion Example scenario: energy consumption for keeping cell temperature within specific range Parametrization of the model Model definitions: Ambient temperature: 20 °C Internal resistance of one cell: 3 mW
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AIT_Dvorak_ThermalBattery.nb
Current load: sequential FTP72 current profiles
Simulation and Results Discussion Preliminary Results: Validated cooling strategy Thermal response of cells during operation
Conclusion and Outlook Conclusion: Developed and implemented thermal model of EV battery including cooling circuit Calibrated thermal battery model
AIT_Dvorak_ThermalBattery.nb
Proved applicability of the model via a practical application example
Outlook Vehicle measurements Discretizing thermal cell models Thermal influence of the battery container Combine accurate electric model with thermal model Development and implementation of further vehicle component models Integration of the thermal battery stack in entire vehicle model
Thank you for your attention! Contact: Dominik Dvorak
[email protected] +436646207837 Mobility Department Electric Drive Technologies AIT Austrian Institute of Technology GmbH Giefinggasse 2, A-1210 Vienna
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