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World Electric Vehicle Journal is published by MDPI from Volume 9 issue 1 (2018). Articles in this Issue were published by The World Electric Vehicle Association (WEVA) and its member the European Association for e-Mobility (AVERE), the Electric Drive Transportation Association (EDTA), and the Electric Vehicle Association of Asia Pacific (EVAAP). They are hosted by MDPI on as a courtesy and upon agreement with AVERE.
Open AccessArticle

The Value of a Clutch Mechanism in Electric Vehicles

Energy and Power Group, Dept. of Engineering Science, University of Oxford
Author to whom correspondence should be addressed.
World Electr. Veh. J. 2013, 6(3), 696-706;
Published: 27 September 2013
This paper examines the benefits of a drivetrain that is able to disengage its propulsion motor from the driveline in an electric vehicle. The drivetrain was developed for an ultra-efficient eco vehicle competing in the Shell 2013 Eco Marathon. Various clutch mechanisms were examined. In spite of the complexity and losses associated with additional bearings and release surfaces, an actuated dog clutch was chosen as it offers superior performance due to the dual capability of freewheeling and regenerative braking that results. Track data from the event is presented along with experimental work that indicates that the clutch mechanism reduces power consumption by more than 35% for a ferrous permanent magnet propulsion motor. Savings were reduced to 5% for a coreless permanent magnet motor coupled to the driveline via an 11:1 straight cut spur gear arrangement. This reduced saving was due to the removal of hysteresis and eddy current losses from the stator. The paper also demonstrates during a competition in which the driver was aware of the energy consumption, the driving style changed when the technological option to free wheel was available. Finally the study was inferred onto a real world application with further experimental and simulation work on the Delta E4 Coupe, a high performance electric sports car. The vehicle uses a ferrous permanent magnet direct drive arrangement, indicated a reduction in power consumption of 10 to 14%. It is hoped that these insights are relevant when considering the development of electric vehicle drivetrains where machine topology and drive cycle will determine the value of a clutch mechanism.
Keywords: Free wheeling; clutch mechanism; ultra-low energy electric vehicle Free wheeling; clutch mechanism; ultra-low energy electric vehicle
MDPI and ACS Style

Camilleri, R.; Armstrong, P.; Ewin, N.; Richardson, R.; Howey, D.; McCulloch, M. The Value of a Clutch Mechanism in Electric Vehicles. World Electr. Veh. J. 2013, 6, 696-706.

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World Electr. Veh. J., EISSN 2032-6653, Published by MDPI AG
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