Gunter Freitag

High-performance and highly efficient electric wheel hub drive in automotive design

The entire drive integration in the wheels of electric cars enables completely new vehicle drive train concepts and liberties within the interior design. Central motor, external gearing, differentials, axels and drive-shafts are no longer required, which leads to an enormous gain 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 wear-out and maintenance expenditure are reduced to a minimum. Decentralized drives also feature new functionalities concerning vehicle dynamics. This aspect counts especially for wheel hub motors because of the direct access to the wheels without any component in between. Thought about the most promising machine type will be presented in this article. Also a suitable construction and assembly is considered. Advantages and disadvantages of the single tooth winding and a segmented stator are discussed. Because installing space is rare especially in this application a special high voltage connection for small packaged machines will be presented. The machine has been realized and assembled. Measurements on the test bench and on the test track are shown to acknowledge the considerations.

Electric Wheel Hub Motor with High Recuperative Brake Performance in Automotive Design

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.