Range Extender Module

The capability of electrical storage referring to capacity and charging operation will in the medium term not be sufficient to offer the accustomed and appreciated flexibility and range of traditional combustion engines. Furthermore, common materials which are needed in a corresponding battery are globally proportionally rare (in particular lithium). Therefore, it is necessary for the foreseeable future to replace pure electric mobile drive by a combustion engine module. Thereby two ways are possible: Either the mechanical power of a combustion engine is directly coupled into the drive train or a generator with minimized conversion loss is used. The electric power of the generator is coupled into a pure electric drive train. Both concepts have to be tested for energy efficiency and feasibility in detail.

Combustion Engines

Combustion Engines as chemical mechanical energy converters can convert chemical energy stored in fuels with a high energy density and efficiencies of more than 50% into mechanical work.
Significantly changed load spectrums, in particular a reduced dynamic, allow new approaches, e.g. an improved combustion management and control (such as HCCI), downsizing by supercharging, variability in the engine and the valve train and waste heat recovery. (Prof. Abel, Prof. Kneer, Prof. Pischinger)
New demands on the acoustic behavior arise from decoupling the power requirement of the car from the power requirement of the range extender module. The research focus lies not only on noise excitation through the combustion itself, but notably also on new approaches on an air and exhaust system. The basic conditions of the integration that are significantly unfavorably geometric than conventional drive exacerbate the problem of charge exchange noise of small range extender engines. Three dimensional and one dimensional simulation of the combustion process und gas exchange will enable the determination of the excitation spectrum already in the context of the basic research. A noise level calculation of the generator dependent on speed and load attached to the cooperation of the researchers in matter of the acoustic behavior provide a basis for researching an optimal range extender module.

Electric Motors

The research of an increasing efficiency and a reduction of cross section, costs and weight is necessary despite of the respectable development of the synchronous machine used in today’s vehicle applications. Machine design and architectures with a reduced iron and copper loss can be identified by simulation of complex magnetic circuits involving transient effects. Moreover, the use of copper based material can be minimized. (Prof. Hameyer)
High-speed generators (e.g. up to 20,000 min-1) can supersede DC/DC boost converters and allow reduction of the machine size. This approach requires the use of appropriate gears and needs an integrated view on the combination of motor and gear. Coupling the high-speed generator with a gear causes a vibratory drive train, which is effected by torque peaks on both the generator and the gears. This strongly influences durability as well as comfort. The aim of this research project coupling the area of the gear and the generator includes minimization of mechanical tolerances and the active damping of the vibrations, e.g. through a state control. In addition to durability, the power density can also be improved by a combined e-motor and gearbox design, which can be applied in the range extender module. Thus, the energy efficiency of the whole vehicle can be increased.