Electric wheel hub motor with high recuperative brake performance in automotive design

Abstract

The entire drive integration in the wheels of electric cars enables completely new vehicle drive train concepts and liberties with the interior design. Central motor, external gearing, differentials, axels and drive-shafts are no longer required, which leads to an enormous gaining of free space for the passenger compartment or other car components. Fully new car concepts and designs will become feasible. As well it can help to reduce weight and costs and increases the efficiency of the whole drive system. In addition wearout and maintenance expenditure are reduced to a minimum. Decentralized electric drives also enable new functionalities mainly concerning vehicle dynamics. This aspect counts especially for wheel hub motors because of the direct access to the wheels without any component in between. Another significant advantage is that direct drives in general are not prone to oscillations during load changes comparing to central drives with transmission gear, coupling and drive-shaft. In this article a review on the development of a wheel hub motor is given that is designed to substitute the friction brake on the rear axle. This demand special thought towards a system that accelerates and decelerates. High torque and power densities are achieved. Furthermore it is designed to be use in typical automotive conditions and vicinities. Indisputable a wheel hub motor adds more weight to the rim. Hence the impact of the increase of the unsprung masses is discussed in this article.