Thermal design & reliability define PSU performance for extreme environments

June 15, 2017 // By Graham Prophet
Powerbox (Gnesta, Sweden) has designed a technology platform to power industrial applications requiring high reliability and resilience in extreme environments, such a providing power to subsea equipment such as gas and oil monitoring and control systems situated on the seafloor.

These subsea systems are supplied by an AC or DC high voltage line feeder; the PRBX VB410-380 power converter delivers 48V DC with very high reliability and resilience. The unit comprises a pre-stage converter and a secondary stage with redundant power modules and, for monitoring and control, a full set of communications and interfaces.


Industrial applications such as gas and oil, situated on the seafloor, or long distance transmission cables, require very specific power solutions to supply a subset of electronic equipment operating 24/7 with no downtime, and where maintenance is either very expensive or simply not an option. These applications are usually powered from the shore or from a technical platform generator via a high voltage line, which depending on the power station could be AC or DC voltage within the range of 300 to 900 VAC, or 400 to 1500 VDC, ultimately requiring a 48V DC intermediate bus voltage to power electronic equipment. Outputs need to be able to operate in parallel in order to increase the power or to offer redundancy.


Equipment deployed in extreme environments such as the seafloor must be designed for very high reliability and resilience and able to operate within a temperature range of -25 to +80 degrees C without derating, using conduction cooling only. Subsea electronic equipment is often contained within a very tight tubular container fixed to the cable. Powerbox’s PRBX VB410-380 is designed to guarantee the maximum level of isolation between the high-voltage input and the low-voltage output, but with sufficient physical isolation between the different components to allow for tight integration.


Using an advanced switching topology the complete system (high voltage input to low voltage output) energy efficiency is over 85%, which compared to earlier generation, similar products is some 10% higher. The PRBX VB410-380 layout is designed and optimized to conduct heat from the dissipative elements to the cold plate, reducing the possibility of internal