42V

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42V stand for a project for the purpose of on-board networks in one of motor vehicles (cars, trucks and buses) electric voltage of 42  V switch. The full name of the project is “42V / 14V-Bordnetz” in German and “42V / 14V PowerNet” in English. A logo was created for the project that was supposed to signal “42 V on board”.

Due to the additional costs, the project and the conversion to 42V on-board electrical systems in the European automotive sector were discontinued.

history

United States

At the Massachusetts Institute of Technology Laboratory for Electromagnetic and Electronic Systems (MIT / LEES) in Cambridge , on the initiative of Daimler-Benz, the first “Workshop on Advanced Architectures for Automotive Electrical Distribution Systems” met in 1994 with the aim of developing the architecture for a future automobile To work out on-board network. In addition to the automobile companies Daimler-Benz, Ford and General Motors, the workshop also included supplier companies from the start.

In September 1995, various on-board network architectures were compared at MIT using the “MAESTrO” tool, and in December 1995 a value of approx. 40 V was fixed for the first time as the future voltage level in the “Conclusions”.

At the beginning of 1996 the “Consortium on Advanced Automotive Electrical and Electronic Systems” was brought into being. At the subsequent workshop in March 1996, the future nominal voltage was defined as 42 V. The article "Automotive electrical systems circa 2005" was published in the IEEE Spectrum in August 1996.

Following the Convergence in October 1996, Professor John G. Kassakian gave the lecture “The Future of Automotive Electrical Systems” at the “IEEE Workshop on Automotive Power Electronics” in Detroit. On March 24, 1997, Daimler-Benz presented the “Draft Specification of a Dual Voltage Vehicle Electrical Power System 42V / 14V” at MIT.

Europe

Parallel to the activities in the USA, the “Board Network Forum” of the automobile companies in Germany was launched in 1994 at the initiative of Daimler-Benz at what was then SICAN GmbH in Hanover. There, too, the suppliers were soon included in the discussion, and all European automotive companies were invited to participate. On February 15, 1996, the position paper "Board network architecture in 2005" was adopted at the Board Network Forum and on June 4, 1996 BMW presented the "Table of current and future consumers in vehicles" and the "42V / 14V board network".

At the 7th international symposium for electronics in motor vehicles in Baden-Baden on September 13, 1996, the lecture “New wiring system architecture and consequences”, given by Richard D. Tabors, attracted attention. On March 6, 1997, BMW presented the “Draft Specification for the 42V / 14V Two-Voltage On-Board Network” in Hanover.

Decisive impulses for the work at SICAN GmbH came from the cooperation between BMW and Daimler-Benz through the joint creation of the European "Consumer List 2005" and the jointly developed "Specification draft for the two-voltage vehicle electrical system 42V / 14V".

Choice of voltage

After preliminary work, the result of which was the "Consumer List of a Vehicle 2005", various electrical system architectures were compared with the tool "MAESTrO" at the Massachusetts Institute of Technology Laboratory for Electromagnetic and Electronic Systems (MIT / LEES) in the September 1995 workshop (12 V, 12 V / 24 Vdc, 12 V / 48 Vdc and 12 V / 60 Vac). The highest possible direct voltage turned out to be the cheapest alternative.

A contact protection limit of 60 V exists for direct voltages, which must not be exceeded even in the event of voltage fluctuations due to extreme conditions. An on-board network with a nominal battery voltage of 48 V was therefore ruled out because the charging voltage of the accumulator can reach 60 V at low temperatures . In the case of accumulators, the number of cells also has an impact on price, weight and volume and should therefore be kept as low as possible.

However, for the introduction of the 42V / 14V on-board network, new battery technologies for automotive applications would not have been available at reasonable costs. These also require special charging regimes and consequently cannot be operated “rigidly” on the on-board network, which is an advantage when it comes to covering power peaks. Lead accumulators are inexpensive and show a very "good-natured" behavior when charging / discharging. Lead-acid batteries would therefore have been energy-optimized or service-life-optimized on the low voltage and used in a performance-optimized manner on the higher voltage.

Another important criterion for a new architecture was that it offers extensive migration options, i.e. the consumers can only gradually be switched to the higher voltage according to the requirements. To understand it, it is necessary to realize that today's 12 V vehicle electrical system has a generator control voltage of approx. 14 V and that this is the predominant voltage. Accordingly, the designation of this branch in the future on-board network has been corrected to 14 V.

Depending on the operating conditions, the on-board network voltage can fluctuate between 6.5 and 16 V today, with a more or less large ripple superimposed on it. In the 42V / 14V on-board network, the 14 V branch should be free of high-power consumers and therefore be able to be kept within significantly narrower limits.

In intensive discussions with the major semiconductor manufacturers, a voltage of approx. 40 V turned out to be advantageous. Many arguments are in the lecture "Intelligent Power Semiconductors for Future Automotive Electrical Systems" from the former Siemens Semiconductor now Infineon from the 17th conference "Electronics in Motor Vehicles" on 3rd / 4th. June 1997 in Munich.

Further arguments for a higher voltage were the reduction of weight in the cabling and the improvement of the on-board network stability, also by reducing the voltage drops. With three times the voltage, thick conductors can be reduced to a third of the cross-section and at the same time the relative voltage drop can also be reduced to a third. With the same cross-section, the relative voltage drop is only one ninth. The voltage level resulting from the abundance of arguments was so close to three times the current voltage that it was almost necessary to choose 42 V for the second voltage level.

implementation

From 2001, Japanese manufacturers and General Motors brought hybrid vehicles with the 42V / 14V two-voltage electrical system onto the market. Although Daimler-Chrysler was one of the initiators of this concept and was planning to implement it in around 2005, it was not used in Germany.

It was clear that the new development of 42 V components would result in increased costs. Ultimately, no German automobile manufacturer wanted to accept the specified additional costs for a changeover, as it did not seem possible to demonstrate a corresponding utility value to the customer for the necessary additional price.

The activities related to 42 V in Europe have meanwhile stopped. Instead, since 2010, German automobile manufacturers have favored the solution for the task of providing a second sub-electrical system with a voltage of 48 volts, which supplements the 12-volt network.

Footnotes

  1. ^ John G. Kassakian, Hans Christoph Wolf, John M. Miller, Charles J. Hurton: Automotive Electrical Systems Circa 2005. Demands for Better Fuel Economy and more Electric Power are Driving Cars to Multiple Higher Voltages. In: IEE Spectrum. August 1, 1999, accessed on December 26, 2015 (English, text without graphics). First published in August 1996 in IEEE Spectrum, Volume 33, No. 8, ISSN  0018-9235 . ( Abstract )
  2. ↑ Intelligent power semiconductors for future vehicle electrical systems Paper of the "Electronics in Motor Vehicles" conference, Munich 1997 (PDF; 93 kB)
  3. ↑ Intelligent Power Semiconductors for Future Automotive Electrical Systems Paper of the "Electronics in Motor Vehicles" conference, Munich 1997 (PDF; 95 kB)
  4. ↑ Tatsuo Teratani, Toyota Motor Corporation: Future Vehicles and Trend with Automotive Power Electronics and Hybrid Technology. (pdf (3.8 MB)) (No longer available online.) In: FT3-1.2. VDE Congress 2006, October 24, 2006, archived from the original on December 27, 2015 ; Retrieved January 5, 2016 (Slide 22 of 30 shows vehicles with a 42V electrical system that went into production between 2001 and 2004).
  5. ↑ Dr. Henning M. Hauenstein: Evolution of the on-board network architecture through a 48-V supply bus. In: elektroniknet.de. Weka Fachmedien GmbH, July 9, 2013, accessed on December 21, 2015 .
  6. ^ Alfred Vollmer: German OEMs set standards. 48 V on-board network, partial network operation and charging interface. In: All-Electronics.de. Hüthig GmbH specialist portal, June 14, 2011, accessed on December 21, 2015 .

literature

  • Alfons Graf: The New Automotive 42V PowerNet . expert-Verlag, Renningen-Malmsheim 2001, ISBN 3-8169-1992-8 .

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