Power Rails can make the Difference

We all know Ohm’s law (R = U / I) and the dependency between power, voltage and current (P = U * I); and we know the outcome: P = I² * R. Being engineers in the power business we know that it is basically a very good idea to keep the voltage level as high as possible because this will lower the currents, which contribute squared to the power losses. This is why and how the system of power supply rails and DC/DC converters was established. Of course, higher voltages bring other challenges to the systems.

When I was a child the battery voltage in cars increased from 6 V to 12 V. In order to re-install the old 6-V car radio in our new car with the 12 V power rail my dad had to install a quite bulky converter. Today, the 12 V rail is standard in passenger cars, and it is about to be more and more substituted by a 48 V rail – at least for in-car units with a high power demand. When I recently talked to Haris Muhedinovic, Engineering Manager at Vicor EMEA, he even said “48 V is the new 12 V” in cars. In order to serve the legacy parts still running on 12 V he suggests using factorized power converters, where the 48 V rail voltage is converted by a constant factor to the 12 V voltage – a component that he literally explains to be a kind of “DC transformer”. And as efficiencies of these DC/DC converters are now in the 98 % range (even with 3.5 kW converters), the conversion losses are really low. By the way: At CES 2026 Clarios announced plans to launch a production-ready 48 V battery based on sodium-ion technology by the end of the decade.

Looking at the new data center architectures, you can see the same trend of higher DC voltage supply rails, which have now arrived at the 800 V level. And even in industrial, building and other industries we now see a trend to consider DC microgrids operating at e. g. 350 V_DC or 700 V_DC as well as higher and lower voltages. In this context I’d like to draw your attention to Current/OS (currentos.org), which is “a nonprofit, open partnership dedicated to ensuring reliable and sustainable hybrid AC/DC power distribution in buildings and installations.” In Aalsmeer, The Netherlands, you can now even visit a “Direct Current Experience Center”, where they talk about up to 20 % in energy savings and up to 50 % savings on copper in this 60 kW microgrid, which has a 20 kW connection to the AC grid.

Bodo’s magazine is delivered by postal service to all places in the world. It is the only magazine that spreads technical information on power electronics globally. We have EETech as a partner serving our clients in North America. If you speak the language, or just want to have a look, don’t miss our Chinese version at bodospowerchina.com. An archive, of every issue of the magazine, is available for free at our website bodospower.com.

My Green Tip of the Month: Summer in the northern hemisphere is just around the corner, and we all know that we will need a lot of cooling. However, we should think about perhaps substituting our old fridges and freezers. If they are older than 10-15 years you will have the opportunity to reduce their “electricity consumption” by more than 50 % – if you buy adequate energy-efficient appliances. And by correctly selecting the temperature in the fridge to 8 °C (48 °F) instead of lower temperatures you will be able to save even more energy.

Kind Regards,
Alfred