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Abstract: Plug-in Hybrids Made Easy – Selectable EV Drive using In-Wheel Motors

Policymakers, consumers and manufacturers are all agreed – the auto industry needs to adopt electrification to address climate change and dwindling natural resources – yet we still see very few hybrid and electric vehicles on the road today. Given the will is there, why the lack of adoption? In reality the main reason is not the technology, but rather the cost of developing the technology in these times of reduced profits and austerity. Using its revolutionary in-wheel motor technology Protean Electric has developed a plug-in hybrid vehicle architecture that can deliver a cost efficient solution to allow rapid electrification of the vehicles we all drive today. Simply put, by fitting a traction battery and a pair of Protean in-wheel motors to a conventional passenger vehicle, the vehicle can be given two additional selectable modes of driving, pure EV and hybrid, with little or no re-engineering of the base vehicle required. In conventional hybrids, to give the same functionality, the chassis system, body-in-white and base powertrain on every platform to be electrified would need to be significantly re-engineered to accept a centralised electric traction motor at substantial cost. It is this drastic reduction in engineering overhead cost that is the key to allowing this hybrid solution to produce cost efficient plug-in hybrids for the mass market. This paper will discuss the engineering involved in converting a conventional vehicle into a selectable drive plug-in hybrid and show how this can be simplified by harnessing Protean’s unique in-wheel motor with integrated power electronics. The paper will cite Protean’s previous work on hybridising a Vauxhall Vivaro LCV and Mercedes E-Class Saloon as examples of proof of concept hybrid conversions using identical in-wheel motors and related systems. The paper will look into all areas of these vehicle conversions, but will focus on 2 key areas of the conversion. First, the fitting of the in-wheel motor to the chassis and overcoming the challenges from packaging and friction brake integration will be discussed. Second, the focus will fall on the development of the hybrid vehicle controller and its integration with the conventional power train and the battery system. The paper will also distil the real world results from these vehicles showing validation testing and in particular the fuel saving benefits found. The paper will go onto discuss the economics of vehicle hybridisation and attempt to show how this innovative solution, offered by Protean’s in-wheel motor, can deliver a viable mass market business case for plug-in hybrids ahead of conventional solutions.