EMiLE integrates power electronics into motor

July 19, 2013 // By Christoph Hammerschmidt
More powerful, more reliable, more cost-efficient on one word: better electric vehicles are the goal of an ongoing research project led by automotive transmission system company ZF. In the project "Emile", a consortium of companies including Bosch, Infineon, Siemens and TDK-EPC along with research institution Fraunhofer and the Aachen Technical University are focusing in integrating power electronics components into the (electric) motor. The integration will have positive effects on efficiency and power density and it will facilitate series production.

In today's electric vehicles, the power electronic components are located in a box close to, but separate from the motor; the connection between the two is accomplished by cables. This approach however has drawbacks: It is voluminous and heavy; the cabling causes costs to rise and reliability to decrease. This is where the consortium led by ZF is attacking: The Project EMiLE (Electric Motor integrated Power Electronics) is looking for ways to integrate the power transistors and other power components into the motor case. The project was designed in close coordination with Germany's National Platform Electromobility, a group of industrial and business experts appointed by the German government.

The experts believe that a close spatial vicinity of power electronics to the stator windings of the motor will result in multiple advantages: It reduces the number of interfaces for the inverters. This in turn enables more compact and lightweight solutions. And it will be more cost-effective than separate solution as we see today. In addition, the integrated approach eliminates several sources for electromagnetic parasitic radiation since the cables carrying these currents are eliminated. At the same time however, the integrated approach bears thermal and mechanical challenges to the power electronics.

In the project EMiLE, the research partners aim even higher: Not only close vicinity of motor and power electronics is the goal, but complete integration of the two, further reducing the number of interfaces and connection points. Not the least this will also offer the option to utilize pre-assembled units to simplify the vehicle's assembly process. In addition, the consortium expects further benefits in the areas of fault control, redundancy, functional safety and power efficiency at system level.

The researchers have ambitious goals: The power density of inverter and motor at system level will be increased by 50%; the system cost will be reduced by 40% compared to a conventional assembly. The cognitions resulting from the project will be used for