Split-voltage E/E architecture takes shape

June 28, 2011 // By Christoph Hammerschmidt
After the recent announcement of a 48 V supply network in future cars, the elements of a split-voltage architecture take shape. It appears that the roll-out schedule is rather ambitious.

Car maker Audi acknowledged the plans to equip next-generation passenger cars with an additional 48 V supply network, communicated a week earlier in a joint statement of all German OEMs. According to Audi, the 48 V supply network will be implemented first in standard cars with Internal Combustion engine. "Our first roll-outs won't include electric vehicles", the company said. Roll-out of first production vehicles will be within three years. Nevertheless, in the mid-term, the goal is to include HEVs as well.

Not all companies involved wanted to talk openly about the topic. Luxury car maker Daimler, for instance, backpedaled and declined to provide any further details - after Daimler E/E expert Volker Wilhelmi had assumed the role of a spokesman in the joint statement. Nevertheless, in talks with various experts EE Times Europe was able to identify the most significant building blocks for the split-voltage architecture.

In fact, the issue is not new; the industry has been discussing a higher supply voltage for high-current applications for more than ten years. But the voltages in discussion as well as the goal for introducing a higher voltage have changed. In the beginning, the focus was on performance and features - for instance, the industry intended to implement advanced systems like steer-by-wire, brake-by-wire, or electric valve control. "Now it is all about CO2 emission reduction", explained Alfons Graf, System Architect for vehicle body systems for Infineon. "In the meantime, the performance topics have been resolved otherwise or became obsolete", he said. Currently, the rationale to implement 48 V is "micro-hybridizing" the cars, with improved recuperation and other measures in the focus. "Also the battery technology has changed", Graf said. "In the beginning it was all about lead acid batteries, now the considerations focus on lithium-ion".

Experts such as Graf expect that within the 12 V domain most elements will remain in place - including market factors such as growth expectations and product strategies.