Accurate Time-Efficient Thermal Modeling and Discretization Methodology Applied to Electric Machines

Abstract

The increasing power density of electric machines for electric vehicles necessitates accurate thermal analysis in design and real-time condition monitoring through simulations with computation times not exceeding one minute. Existing thermal models are either accurate and complex while requiring large computation times or they are fast but lack accuracy. To address these challenges, a novel hybrid modeling methodology is proposed, combining 3D lumped parameter thermal networks with thermal resistances extracted from 2D finite element models (FEM) to reduce computation demands while preserving accuracy. Further, a methodology is introduced to define the thermal network discretization for a desired threshold accuracy while minimizing computation time. Analysis of this discretization methodology demonstrates that the desired accuracy can be reliably achieved with limited computational effort. Verification of the modeling methodology against 3D FEM in OpenFOAM shows key component temperature deviations of less than 0.67 °C in steady-state simulations and 0.75 °C in transient simulations, comparable to the 3D FEM uncertainty of 0.39 °C. The computation times for steady-state and transient simulations are 18.3 s and 43.5 s respectively compared to 44 h and 175 h for 3D FEM. This highlights the time efficiency of the proposed methodology while maintaining accuracy for key component temperatures.

Acknowledgments

The authors would like to acknowledge Dana Incorporated for supporting this research work.

Disclosure statement

The authors report there are no competing interests to declare.

Additional information

Funding

This research was supported by Flanders Make, the strategic research center for the manufacturing industry, and the HERMESFONDS in the framework of the Hipercool project (HBC.2016.0463) and SingleOilCnL project (HBC.2020.2009).

Notes on contributors

Jasper Nonneman

Jasper Nonneman received his M.Sc. degree in Mechanical Energy Engineering in 2016, from the Faculty of Engineering and Architecture, Ghent University, Belgium. He is currently working as a PhD researcher at the research group Sustainable Thermo-Fluid Energy Systems of the Department of Electromechanical, Systems and Metal Engineering at Ghent University, Belgium. His research interests are thermal management, modelling, and experimental investigation of electric drivetrains, with the focus on electric machines and power electronics.

Ilya T’Jollyn

Ilya T’Jollyn is a research professor at the University of Antwerp. He received his M.Sc. degree in Electromechanical Engineering from Ghent University, Ghent, Belgium in 2014. In 2021, he successfully defended his doctoral dissertation with the title ‘Assessment of Nucleate Pool Boiling Heat Transfer and Critical Heat Flux for Power Electronics Cooling with a Low-GWP Refrigerant’. He is part of the Energy and Materials in Infrastructure and Buildings (EMIB) research team at the University of Antwerp. His research includes numerical simulations and experimental work on complex flows and heat transfer with applications in buildings, building energy systems and electric drivetrain thermal management.

Michel De Paepe

Michel De Paepe is professor of Thermodynamics and Heat Transfer at the Faculty of Engineering and Architecture of the Ghent University. He graduated as M.Sc. in Electromechanical Engineering at the Ghent University in 1995. In 1999 he obtained the PhD in Electromechanical Engineering at the Ghent University, graduating on `Steam Injected Gas Turbines with water Recoverý. Michel De Paepe is currently part of the Research Group Sustainable Thermo-Fluid Energy Systems at the Faculty of Engineering and Architecture of the Ghent University. Research in this group focuses on: thermodynamics of new energy systems, performance of HVAC systems and energy in buildings and complex heat transfer phenomena in industrial applications, as in compact heat exchangers, combustion engines, electrical drives, refrigerant two-phase flow and electronics cooling. Michel De Paepe was supervisor/promotor of 30 PhDs defended at Ghent University. He is (co)author of 156 papers published in international peer reviewed journals and more than 450 conference papers.