Column: Electric Vehicles
Power delivery networks at the crossroads
By Henryk Dabrowski, VP of Sales, Vicor Corporation E
lectric and autonomous vehicles, high-performance computing, communications and network infrastructure are among the many industries requiring ever-increasing power levels. And with those rising power levels, challenges for system designers grow,
with many now considering moving their power delivery networks (PDNs) away from 12V to 48V. Tese new complex loads require new architectures, built for increased performance and high current density at the point of load (PoL). Every electronic piece of equipment or system has a PDN made
up of cables, busbars, connectors, circuit board copper power planes, and AC-to-DC and DC-to-DC converters and regulators. A PDN’s performance is governed by its architecture, the use of AC or DC voltage distribution, specific voltage and current levels and when and how many times the network needs voltage conversion and regulation. Several industries have standardised their PDNs, such as 270V
and 28V in the defence and aerospace industry, negative 48V in communications infrastructure applications and 12V PDN in automotive (Figure 1) – now also adopted in computer servers and industrial applications. As a result, a billion-dollar industry is built around standard PDNs. However, with a growing number of loads and increasing load
power (Figure 2), 12V PDNs are overstretched. And as industries transition to new PDNs – 48V, 400V and 800V – there’s the opportunity to substantially improve performance with non- traditional power delivery architectures and technologies.
The emergence of 48V Te telecommunications industry has been using 48V PDNs for decades, because: 1. It is safety extra low voltage (SELV) – i.e., it carries a low risk of electrical shock.
2. Small-gauge wire can carry the current long distances with minimal voltage drop.
3. An ‘always on’ requirement drove the industry to large lead- acid rechargeable 12V battery banks connected in series to deliver 48V.
14 May 2023
www.electronicsworld.com
Figure 1: Vicor 3-phase 12V PDN As communications networking infrastructure grew in
complexity, the 48V PDN infrastructure added many new, complex loads consisting of arrays of processors, memory and control systems. Tis posed a challenge, since most of the technologies were centred on 12V, with semiconductor converters and regulator components optimised for this operating voltage. To solve this 48V-to-12V transition problem (Figure 3), the
Intermediate Bus Architecture (IBA) was developed, becoming the de facto standard in communications and network infrastructure applications. Intermediate bus converters (IBCs), which are isolated, non-regulated, fixed-ratio (1/4) converters, were developed by several companies and built in an open-frame package that met DOSA and POLA pinout standards to allow multi-sourcing. Isolation was not a safety requirement for the SELV IBA because
positive battery terminals were tied to ground to stop galvanic corrosion, resulting in negative 48V voltage. By using an isolated fixed-ratio bus converter as a DC-DC transformer, a –48V input could then be used to deliver a +12V output to the downstream PoL regulators. Now, advanced applications such as artificial intelligence (AI) in data centres are driving the move from 12V to 48V PDNs and away
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