ABSTRACT Electric vehicle development is at a crossroads. Consumers want vehicles that offer the same size, performance, range, reliability and cost as their current vehicles. OEMs must make a profit, and the government requires compliance with emissions standards. The result - low volume, compromised vehicles that consumers don't want, with questionable longevity and minimal profitability. In-wheel motor technology offers a solution to these problems; providing power equivalent to ICE alternatives in a package that does not invade chassis, passenger and cargo space. At the same time in-wheel motors can reduce vehicle part count, complexity and cost, feature integrated power electronics, give complete design freedom and the potential for increased regenerative braking (reducing battery size and cost, or increasing range). Together, these advantages create the tipping point for OEM acceptance of in-wheel-motor technology, offering them an immediate opportunity to build larger electric and hybrid vehicles, including full-size sedans and SUVs -vehicles that consumers want and are profitable to manufacture. INTRODUCTION OEMs are currently modifying the architecture and design of their entire range to better respond to customer demand for greener more efficient vehicles and the regulatory actions curbing greenhouse gas emissions. Accordingly, manufacturers are planning to rapidly expand the implementation of advanced vehicle, powertrain and engine technologies. In addition to the implementation of new powertrain technologies, the reduction in mass and size of the vehicle systems, sub-systems and components has also shown very promising opportunities for decreasing total vehicle emissions and running costs. Overriding this, consumers wantvehicles that offer the same size, performance, range, reliability and cost as their current vehicles, but OEMs must make a profit, and the government requires compliance with emissions standards. How can the advanced vehicle technology and diverse and often conflicting requirements come together to create the new fleet of desirable and economically viable vehicles? This paper will explore in detail the technology of in-wheel motors (IWMs), the challenges of their integration into vehicles and how they can make a real difference to the economic viability of vehicles in a changing consumer and regulatory framework. We aim to show the reader both the opportunities and challenges surrounding IWMs; the benefits around packaging, performance and economics, and how the technical challenges of unsprung mass, brake integration and cost are being addressed in a manner suitable for the eventual adoption by automotive OEM's. Most vehicles on our roads share a fairly similar basic layout; that of a single engine driving through a gearbox driveshaft, differential, then half shafts to the wheels. Variations of this arrangement have been used for over 100 years with very few changes to the basic layout. In recent years, electric and hybrid vehicle development has gained prominence among major OEMs and specialist companies. The vast majority of these electric/ hybrid vehicles still use variations of this same layout; a large, centrally mounted motor, driving through a gearbox, driveshaft and differential. An alternative arrangement does exist for these electric/ hybrid vehicles, namely through the use of in-wheel motors; where the electric motors are housed inside the wheels themselves. This allows a far greater level of vehicle design flexibility than is possible with traditional centrally-mounted motors. It also frees more space inside the vehicle's body for batteries and allows each driven wheel to be controlled The Technology and Economics of In-Wheel Motors2010-01-2307 Published 10/19/2010 Andy Watts, Andrew Vallance, Andrew Whitehead, Chris Hilton and Al Fraser Protean Electric Copyright © 2010 SAE International SAE Int. J. Passeng. Cars - Electron. Electr. Syst. | Volume 3 | Issue 2 37Downloaded from