It is common knowledge that electronics in automobiles has become more and more sophisticated and that the power consumption only seems to increase. In recent years, the proliferation of gasoline-electric hybrid cars has created new cooling problems with electronics that control large amounts of current. This, of course, is in addition to the challenges of keeping vehicle occupant's comfortable, engines cool and maintaining low aerodynamic drag under a wide range of environmental conditions. All of these considerations highlight the importance of analyzing thermal management for the automobile as a system rather than as independent components.
The Toyota Prius hybrid automobile contains many examples of vehicle electronics that present new thermal challenges to vehicle designers. In a US Department of Energy evaluation of the Prius’ electric drive system, it was found that peak energy dissipation could be over 5kW. This would be unheard
of in traditional vehicle electrical systems, and traditional aircooling would be insufficient.
The Prius’ motor controller is based on insulated gate bipolar transistors (IGBTs), which are cooled by a cold plate. A water and ethylene glycol coolant circulates through the cold plate and through internal passageways in the motor/generator housing. This coolant loop is separate from that of the internal combustion engine, since it operates about 30°C cooler. The heat exchanger for the electronics cooling loop is attached to the main vehicle radiator, and can be seen in the Figure.
This article, written by the engineers at Advanced Thermal Solutions, Inc., Norwood, MA, explores this topic further and looks at some techniques and approaches. (ATS is an engineering and manufacturing company supplying complete thermal and mechanical solutions, from analysis and testing to final production.) To read the article, which is used with permission, click here.