42-volt electrical system
42V switch was for a project with the aim of the electrical systems of motor vehicles ( cars, trucks and buses ) to a voltage of 42V. German: " 42V/14V-Bordnetz " English: " 42V/14V PowerNet ". The logo should be " 42 V on board " symbolize. Due to the additional costs of the project and the switch to 42V electrical systems in the automotive sector have been set.
History
United States
At the Massachusetts Institute of Technology Laboratory for Electromagnetic and Electronic Systems ( MIT / LEES ) in Cambridge in 1994, met at the initiative of Daimler -Benz, the first " Workshop on Advanced Architectures for Automotive Electrical Distribution Systems " with the aim of the architecture for a future automobiles board power supply to work. Participants in this workshop were next to the car companies, Daimler -Benz, Ford and General Motors from the outset suppliers.
In September 1995, at MIT various wiring systems architectures with the tool " Maestro " and compared for the first time fixed in December 1995 in the "Conclusions " as a future stress level a value of about 40 V.
In early 1996, the " Consortium on Advanced Automotive Electrical and Electronic Systems " was launched. On the subsequent workshop in March 1996, the future nominal voltage of 42 V was defined. In IEEE Spectrum was released in August 1996, the article " Automotive electrical systems circa 2005 ."
Following the Convergence held in Detroit in October 1996 Professor John G. Kassakian under the " IEEE Workshop on Automotive Power Electronics " the lecture "The Future of Automotive Electrical Systems ". On 24 March 1997, Daimler -Benz at MIT the "Draft Specification of a Dual Voltage Vehicle Electrical Power System 42V/14V " presented.
Europe
Parallel to the activities in the U.S. in 1994 was also called the "Forum board network " of the automotive companies in Germany launched on the initiative of Daimler -Benz at the former SICAN GmbH in Hannover. There, too, the suppliers were soon involved in the discussion with, and invited all European automotive companies to participate. On 15 February 1996, the position paper "on-board network architecture in 2005 " was posted on the forum board power and decided on 4 June 1996 by BMW, the " table of current and future consumers in the car " and the " 42V/14V-Bordnetz " presented.
Attention was given at the 7th International Conference on Electronic Systems for Vehicles, Baden-Baden on 13 September 1996, the lecture " New wiring system architecture and consequences", given by Richard D. Tabors. On March 6, 1997 in Hanover by BMW of " draft specification for the two- voltage onboard power supply 42V/14V ".
Decisive impetus for the work for SICAN GmbH came from the collaboration of BMW and Daimler -Benz through the joint creation of the European " Consumers List 2005 " and the jointly developed " draft specification for the two- voltage onboard power supply 42V/14V ".
Choice of voltage
After preliminary work, the result of the " consumer - list of a vehicle in 2005 ," was different wiring systems architectures with the tool "Maestro" were at the Massachusetts Institute of Technology Laboratory for Electromagnetic and Electronic Systems ( MIT / LEES ) in the workshop September 1995 compared ( 12 V, 12 V/24 Vdc, 12 Vdc and 12 V/48 V/60 Vac). In this case, a very high DC voltage showed a favorable alternative.
Restrictive, there is a contact protection limit of 60 V, which must not be exceeded even when voltage fluctuates due to extreme conditions for DC voltages. This eliminated an electrical system with a nominal battery voltage of 48 V, because then at low temperatures, the charging voltage of the battery can reach the height of 60 V. For accumulators is also the number of cells of influence on price, weight and volume and should therefore be kept as low as possible.
To introduce the 42V/14V-Bordnetzes new battery technologies for automotive applications would not have been at a reasonable cost. These also require special charging regime and therefore can not be operated " rigid" on -board network, which is in the coverage of peak power advantage. Lead-acid batteries are inexpensive and show the loading / unloading a very " forgiving " behavior. It would have been used energy- optimized on the low voltage and lifetime- optimized and optimized for performance on the higher voltage lead-acid batteries.
Another important criterion for a new architecture was that they offer complete migration option, ie, the consumer, if necessary, the requirements can be reassigned to the higher voltage only gradually accordingly. To understand it is necessary to be clear that today's 12 -volt electrical systems has a generator control voltage of about 14 V and this therefore the prevailing tension. According to the wording of this branch has been corrected in the future vehicle electrical system to 14V.
Depending on the operating conditions of the vehicle electrical system voltage can now vary from 6.5 to 16 V, whereas still a more or less large ripple is superimposed. In 42V/14V-Bordnetz the 14 V - branch should be exempt from consumers high performance and therefore can be kept in a much narrower limits.
In -depth discussions with the major semiconductor manufacturers, a voltage of about 40 V showed to be advantageous. Many arguments in the lecture " Intelligent Power Semiconductors for Future Automotive Electrical Systems " ( " Intelligent Power Semiconductors for Future Automotive Electrical Systems " ) of the former Siemens Semiconductors now Infineon of the 17th conference on " Electronic Systems for Vehicles " on 3/4 June 1997 summarized in Munich.
Further arguments for a higher voltage were the reduction of weight in the wiring and the improvement of the onboard network stability by reducing the voltage drops. With a triple voltage conductor thickness can be reduced to one third of the cross section and at the same time, the relative voltage drop also in a third. With the same cross section of the relative voltage drop is only one-ninth. The resulting from the abundance of arguments voltage situation was so close to three times the present-day stress that it is literally forced upon to choose 42 V for the second voltage level.
Present Status
Originally, the introduction of the two- voltage onboard power supply 42V/14V was planned for around 2005. It was clear that the new development of 42 V components would cause corresponding costs. The strong standing of the automobile manufacturers at 14 V components under price pressure suppliers hoped at 42 V to improve their margins. Ultimately, wanted to take the quantified costs for a change in buying any automobile manufacturers. The activities relating to 42 V are set now.