Abstract
As the age of crude oil gradually finishes and political arrangements all over the world force a continuous reduction of global carbon dioxide (CO2) emissions, energy efficiency worldwide becomes a major challenge for the automotive industry. The European goal of a fleet average emission for all new cars of 130 g/km CO2 by 2012 afford an overall energy efficiency increase of the entire vehicle (5). The political arrangements on the one hand and the expectations of the customer on consistent vehicle comfort and vehicle dynamics on the other hand force the electrification of power train systems. One way to come up to this trade-off is the electrification of the rear axle. The present paper focuses on a hybrid power train concept with a combustion engine in the front and two in-wheel motors at the rear drive shafts. Considering the resulting geometric restrictions due to the wheel rim, the paper gives an impact on different design characteristics of the investigated electric motor types. Another main focus of the article is the representation of the operational advantages and disadvantages of different electric motor types on their potential application as rear axle power units. The article tries to convey fuel saving potentials by electrification for a specified operation strategy and represents the impact of energy efficient control of the investigated electric motor types in the New European Driving Cycle. The technical expertise of the current research project tries to represent a constructive and operational comparison of different electric motor types focusing an in-wheel application scenario at the rear drive shafts. It gives an overview of motor selection issues and energy saving potentials by an energy efficient control of the investigated electric power train concepts.
Keywords: in-wheel motor, induction machine, synchronous machine, energy efficiency, minimal loss control