Automotive electronics power up
By 1994, Mercedes Benz AG, in Stuttgart, Germany, realized that it would need a higher voltage to support the power-hungry electrical systems envisioned for future production vehicles. The electrical load had been growing annually as features were added to cars--electronically positioned seats, steering wheel warmers, seat warmers, and windshield de-icers, for example. Adding a second 12-V battery offered a quick short-term solution, but one that involved squeezing more equipment underneath the car's hood. Mercedes sought a more elegant option--a higher system voltage, but how high?
The German automaker also realized that the decision on which voltage to use could not be unilateral, but rather one that had the complete support of the international auto industry. To foster such an agreement, Mercedes Benz asked the Massachusetts Institute of Technology (MIT), in Cambridge, to organize a working group of automakers and suppliers. The university was already doing electrical system research for the company, working on computer-aided design tools to help engineers design electrical systems for vehicles.
Responsibility for this new task fell to MIT's Laboratory for Electromagnetic and Electronic Systems. On 25-26 October 1994, the laboratory hosted an initial working group meeting of seven companies--AFL Automotive Division (then Electro-Wire), AMP, Delphi Packard Electric, Ford, General Motors, Siemens Automotive, and United Technologies.
These companies, plus representatives from Mercedes and MIT, met regularly for a year and a half, considering issues of safety, reliability, infrastructure, and transition costs. The result was a set of recommendations proposing a system voltage of 42 V. All the recommendations were made public in an IEEE Spectrum article, "Auto-motive electrical systems circa 2005," August 1996, pp. 22-27 [www.spectrum.ieee.org/spectrum/aug96/features/auto1.html].
A year after the creation of the MIT Working Group, Mercedes Benz organized a meeting of German automakers to consider similar issues. The MIT group's recommendations were presented to this German group, which immediately adopted them, though no manufacturer has yet implemented them in a production vehicle.
The German group, known as the Forum Bordnetz, has now been expanded to include all European automakers and many suppliers. Its work is organized and facilitated under the auspices of Sican, a German microelectronics design services company. Forum Bordnetz has assumed principal responsibility for refining the recommendations and turning them into standards proposals for the International Organization for Standardization (ISO).
Meanwhile, in January 1996 the original MIT working group was transformed into the MIT Consortium on Advanced Auto-motive Electrical/Electronic Systems and Components, and its membership expanded to 44 companies, including 16 based in Japan. Because nearly every leading automaker and supplier worldwide is involved in the consortium, the 42-V system voltage is currently perceived to have comprehensive international acceptance. Work now focuses on how the new system, called the 42V PowerNet by consortium members, will be structured: whether single or dual voltage, single or dual battery, and so on.
To spur component prototyping and general knowledge of the 42V PowerNet, the consortium designed a symbol for the new system voltage to rally around. Manufacturers and suppliers wishing to differentiate components and products intended specifically for the new 42V PowerNet can use the logo and the mark to do so. The logo is primarily for promotional purposes, but the mark is intended to be used on the product itself to prevent its misuse in today's 14-V system. Neither the logo nor the mark is protected by copyright as consortium members wish to make them available to all interested parties through the Internet [see http://auto.mit.edu/consortium/].
--J.G.K.
IEEE Spectrum May 2000 Volume 37 Number 5