Title: An electric motor thermal management system for hybrid vehicles: modelling and control

Authors: Xinran (William) Tao; Kan Zhou; John R. Wagner; Heath Hofmann

Addresses: Clemson University, Clemson, SC 29634, USA ' University of Michigan, Ann Arbor, MI 48109, USA ' Department of Mechanical Engineering, Clemson University, 102 Fluor Daniel Building, Clemson, SC, 29634, USA ' University of Michigan, Ann Arbor, MI 48109, USA

Abstract: The HEV e-motor's internal temperature significantly influences its torque/power capabilities. The dominant heat sources are located within the e-motor stator windings and create 'hot spots'. To keep the motor functioning properly without exceeding the established temperature limits, a new cooling concept for PM e-motors featuring advanced controllers is proposed. Firstly, a reduced-order finite element model describes the e-motor's thermal behaviour. Next, an optimal regulator calculates the ideal (target) heat removal rate at its cooling surface. Lastly, a nonlinear tracking controller governs the cooling system operation. Numerical simulation has been conducted to validate the cooling concept. In the urban assault cycle, the stator hot-spot temperature is stabilized with an average error of 0.13°C and a 68% power consumption reduction achieved when compared to classical control. Similarly, the cooling system power consumption is reduced by 28.9% with the proposed controllers for the convoy escort driving cycle.

Keywords: electric motors; hybrid electric vehicles; nonlinear control; simulation; thermal management; hybrid vehicles; modelling; temperature limits; cooling; reduced-order FEM; finite element method; heat removal rate; tracking control; energy consumption.

DOI: 10.1504/IJVP.2016.078557

International Journal of Vehicle Performance, 2016 Vol.2 No.3, pp.207 - 227

Received: 11 Sep 2015
Accepted: 02 Feb 2016

Published online: 17 Aug 2016 *

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