Column: Electric Vehicles
Figure 2: Vicor’s highest-performance power modules
from IBA to new architectures. T e signifi cant rise in processor and associated server rack power levels has simply exceeded what 12V and IBA can deliver. In the automotive market the need to meet legislation and emission reduction in vehicles
new standards that require CO2
was a catalyst to explore electrifi cation. T is has resulted in the emergence of 48V batteries to support new mild-hybrid powertrain, safety and entertainment system designs.
New, higher-voltage PDNs With the advent of higher system power requirements, PDNs based on 380V and 48V are more complex as many industries are still trying to retain legacy 12V PDN infrastructure at the point of load. Additional PDN challenges come in the form of new, high-voltage bulk power sources such as 800V batteries in pure electric (EV) and high-performance vehicles. In these new systems and applications power delivery can be
segmented into three main categories: 1. Bulk power conversion to 48V; 2. Intermediate bus power delivery at 48V and then conversion and sometimes regulation to 12V;
3. Point-of-load power delivery with conversion and regulation from 12V and 48V.
Bulk power delivery T e opportunities for innovating bulk power conversion to an intermediate 48V PDN lie in the following: 1. Achieving higher power density; 2. Using a modular approach to achieve redundancy and scaleability;
3. Enabling advanced cooling techniques with thermally-adept planar packaging;
4. Using high-effi ciency fi xed-ratio converters and leaving regulation to the downstream components. Managing the size and weight of the bulk power converter and cooling it due to higher power losses are primary areas of focus
Figure 3: Vicor -48V PDN
in most applications. If size and weight are not of concern, then equipment can be added for high effi ciency, using fan cooling for its thermal management. However, most applications now require higher power density.
Power engineers should consider using power modules to design and build large converters, rather than discrete-based designs from the ground up. Power modules combined with innovative architectures, topologies, control systems and packaging can signifi cantly improve bulk PDN performance. If the bulk power source is AC or high voltage (Figure 4), then
DC isolation is required. An isolation stage adds power loss in any converter, but regulation may not be necessary if the intermediate bus PDN contains regulation for the PoL stage (i.e., 48V to 12V). T e two considerations for this approach are: 1. Input range of the power source (the fi xed-ratio converter will refl ect this input voltage to the output based on its turns ratio or K factor, just like a transformer) and the input voltage range of the downstream converters/regulators.
2. In the case of a three-phase AC power source, does the system need power factor correction?
www.electronicsworld.com May 2023 15
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