Advanced Models for Electric Machines and Drives

Principal Investigator: Heath Hofmann, University of Michigan,
Student: Kan Zhou, University of Michigan
Government: Wesley Zanardelli, Matt Castanier, U.S. Army TARDEC
Industry: Lei Hao, General Motors

Colored fringe plot of rotor temperatureElectric propulsion, or electric machines and their corresponding power electronic drives, is a key component of electric/hybrid electric vehicle powertrains. The performance of electric propulsion is thermally limited. Hence, in order to determine the power capabilities of an electric machine and drive under real-time operating conditions, knowledge of internal temperatures is required. Thermal models of electric machines and drives would therefore be useful in full-scale electrified vehicle powertrain simulation, as well as in the development of optimal system-level energy control strategies for the vehicle. However, in order to be of use in these applications, the thermal models must be both accurate and computationally efficient, so as not to unduly lengthen overall vehicle simulation times.

The goal of this project is the development of computationally-efficient dynamic thermal models for electric machines, which should be accurate enough to predict temperature, and fast enough for vehicle powertrain simulation and optimization of driving cycles. This project is part of a broader effort within the ARC to model and simulate all aspects of an electrified powertrain. In particular, the proposed work is in close collaboration with Dr. Zoran Filipi’s ARC project on vehicle powertrain simulation and controls development. The model will also be used in Dr. John Wagner’s ARC project on HEV thermal management.


  • Zhou, K.; Pries, J.; Kim, Y.; Lee, TK.; Filipi, Z; Hofmann, H. “Computationally-Efficient Finite- Element-Based Thermal Models of Electric Machines”, Vehicle Power and Propulsion Conference (VPPC), 2011 IEEE, 6-9 Sept. 2011.
    doi: 10.1109/VPPC.2011.6043205
  • Pries, J.; Hofmann, H.;, “Magnetic and Thermal Scaling of Electric Machines”, Int. J. of Vehicle Design, 2013 Vol.61, No.1/2/3/4, pp.219 - 232. doi:10.1504/IJVD.2013.050849
  • J. Pries, H. Hofmann, “Magnetic and thermal scaling of electric machines”, International Journal of Vehicle Design, vol. 61(1), pp. 219-232, 2013.
  • K. Zhou, J. Pries, H. Hofmann, "Computationally-efficient 3D finite-element-based dynamic thermal models of electric machines", IEEE International Electric Machines and Drives Conference (IEMDC), 2013.
  • K. Zhou, A. Ivanco, Z. Filipi, H. Hofmann, "Finite-element-based computationally-efficient electric machine model suitable for use in electrified vehicle powertrain design optimization", 29th Annual IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 1598 - 1603, March 2014.
  • A. Ivanco, K. Zhou, H. Hofmann, Z. Filipi, "A Framework for Optimization of the Traction Motor Design based on the Series-HEV system level goals", SAE World Congress & Exhibition, SAE Technical Paper 2014-01-1801, 2014.