Electric Entertainment

All surveys indicate that a majority of drivers would prefer an electric car over a fuel-based one - if it was fast enough and ran long enough. However, one tiny problem escaped the attention of the public until now: Radio.

The 'vehicle of the future', the electric car, makes listening to the radio a bit difficult since electrical interference impedes the reception of radio waves. These disruptions are caused by the frequency converter, which changes electrical energy into mechanical energy so as to control the electric motor’s speed and direction of rotation. These converters turn the current and the voltage on and off rapidly and frequently, and the way they chop electrical energy up in fractions of a second produces electromagnetic interference.

To get around this problem, not only must the engine’s cabling be shielded, the motor itself needs to be insulated – but this comes with a high price tag for automakers. Researchers at the Fraunhofer Institute for Reliability and Microintegration IZM in Berlin have worked out how to reduce these costs.

Dr. Eckart Hoene, director of the Power Electronic Systems research group, and his team have developed a whole series of tools and methods for reducing interference. Using new simulations and calculation methods, the engineers can for instance now determine where in the vehicle components should be positioned to keep their electromagnetic interactions to a minimum.

»The size and position of individual components – including the electric motor, the battery, the air-conditioning compressor, the charging system, the DC/DC converter and the frequency converter itself – play a crucial role. How and in what direction cables are installed is just as important, as is the thickness of their insulation,« explains Hoene. »With the help of simulations, we can also advise on the quality of the insulation and the plug connectors.«

The scientists have measurement techniques that allow them to pinpoint where exactly in the vehicle interference is coming from and to see how it spreads. What’s more, they have developed a symmetrical power module which stops interference from being emitted. This is a component of the converter and already exists as a prototype.

All German automakers have benefited from the Fraunhofer experts’ know-how. But as Hoene points out: »We advise not only German automotive manufacturers and suppliers, but increasingly Japanese and American companies, too.« Tests and fault analyses can be carried out in the institute’s own laboratory.

Electromagnetic interference is not just a problem in electric and hybrid drives. It can be a problem anywhere power electronics are installed: in avionics, or in wind and solar energy facilities, too. »Roofs with photovoltaic arrays will have a solar converter to change the direct current into alternating current, and this can impair radio reception inside of houses,« Hoene adds.

Comments

[Nissan Dealer]

I actually had no idea that radio signals could be affected in an EV. That's very interesting. Personally I'm fine listening to my ipod or cd's if it means going green.