INTRODUCTION In-wheel motors offer a way to revolutionize the automotive industry through a technology that can add electric drive to any conventional vehicle, without affecting the existing drive-train thereby maximizing design reuse. In order to achieve this, several practical hurdles have to be overcome regarding the integration of these motors. Protean's real-world experience gained over a wide variety of vehicle retrofit programs illustrates some of these challenges and gives practical examples of the measures taken to overcome them. Examples cited will include a sub-compact 3-door C segment vehicle, a mid-size luxury car and a full size pick-up truck in pure electric format, plus a mid-size commercial van and a luxury 4-door sedan in a parallel hybrid configuration. When an in-wheel motor is referred to in this document it is assumed to be one having the optimum characteristics of being of a direct drive design with the power electronicsmounted inside the motors themselves. An example of this type of motor is the Protean Drive™ from Protean Electric. The braking, control and high voltage systems are treated in detail and the issue of added unsprung mass is discussed. Functional safety is treated in the context of the ISO 26262 standard. Finally the in-wheel motor requirements, particularly relating to torque and packaging, are explained with reference to specific vehicles. The paper is organized as follows: 1. Brake Integration 1.1. Do We Need Brakes? 1.2. Do We Have to Change the Brakes? 1.3. Diameter is Key 1.4. The Brakes In Detail 1.5. Future Braking Opportunities 2012-01-1037 Published 04/16/2012 Copyright © 2012 SAE International doi:10.4271/2012-01-1037 saealtpow.saejournals.org Integrating In-Wheel Motors into Vehicles - Real-World Experiences Andy Watts, Andrew Vallance, Al Fraser, Andrew Whitehead, Christopher Hilton, Helen Monkhouse, John Barrie-Smith , Sunoj George and Michael Ellims Protean Electric ABSTRACT Compact direct drive in-wheel motors with integrated inverters, control and brakes offer a number of distinct advantages compared to conventional electric drive systems. The most obvious being that the drive-train is now packaged within the wheel freeing up space elsewhere, in addition many driveline components and their associated losses are eliminated and the vehicle efficiency, response and handling can be improved. In new vehicle applications this allows complete freedom for designers to optimize the vehicle layout, have more usable space inside the vehicle body and enables revolutionary vehicle concepts (which will become more important as road space becomes scarce and taxation measures migrate towards vehicle size). In retrofit applications the compact package allows an electric drive to be added to any existing vehicle without requiring any significant disruption to the vehicle platform to keep integration costs down. This represents an opportunity for OEM's to hybridize their existing vehicle portfolio in order to address more stringent fleet- average emissions legislation. Protean has retrofitted its Protean Drive™ in-wheel motors to a variety of different vehicles in both pure EV and hybrid configurations and has collated its findings over three years of track and road testing. This paper will distil the practical experience gained from these vehicle programs and illustrate some of the challenges and solutions associated with in- wheel motor integration. In doing so the paper deals with many of the key vehicle level topics, such as the CAN interface, vehicle control strategy, and brake integration. ____________________________________ 289CITATION: Watts, A., Vallance, A., Fraser, A., Whitehead, A. et al., "Integrating In-Wheel Motors into Vehicles - Real- World Experiences," SAE Int. J. Alt. Power. 1(1):2012, doi:10.4271/2012-01-1037.Downloaded from SAE International by Univ of Nottingham - Kings Meadow Campus, Monday, September 17, 20182. Control Systems 2.1. Vehicle Control System