German carmakers agree on 48V on-board supply, charging plug

June 16, 2011 // By Christoph Hammerschmidt
Car makers Audi, BMW, Daimler, Porsche and Volkswagen have agreed to jointly incorporate a number of common architectural elements for their on-board power network. These include an additional 48 V section and a charging connector type for all electric and hybrid vehicles as well as CAN bus interfaces supporting partial network operation.

At the 15th Automobil Elektronik Kongress in Ludwigsburg, the companies announced to establish a 48 V supply network supplementing the current 12 V supply. They also said they agreed upon measures supporting CAN bus network segmentation and a common charging plug as a joint de-facto standard.

"At a growing extend, high-current loads are utilized in the vehicles," said Volker Wilhelmi, Head of Electrical/Electronic on-board networks for Daimler. "It becomes increasingly difficult under technological and cost aspects to implement these functions and devices in a 12 V supply network." For this reason, E/E engineering managers of the five OEMs agreed to implement a supplementary 48 V supply in future car generations. Both subnets will be connected through a bidirectional DC/DC converter. "This enables us to integrate high-current devices into our cars at lower cost, better quality and more easily", Wilhelmi said. In particular, the 48V option will improve power recuperation in electric and hybrid electric vehicles and thus reduce CO2 emissions. In addition, powerful actuators can be implemented at smaller form factors. Also heating and air conditioning could benefit from the higher operating voltage.

In their statement the OEMs made clear that they all are developing 48V components and requested the semiconductor providers and control unit manufacturers to actively join the development process for serial production. However, no timeline was provided.

The implementation of an additional 48 V supply network in the vehicles translates in major design challenges for suppliers across the value chain. In particular, providers of semiconductors and ECUs will be affected - they need to adjust their product range to the higher voltage and in part re-design their products. However, no semiconductor manufacturer contacted by EE Times Europe was able to comment.

The second part of the announcement referred to the CAN data bus. The OEMs agreed that in specific situations it should be possible that only parts of the data bus are activated. The OEMs —