Power Supply Modes: Constant Power

[electroalchemist]

Hi, I’m curious about the applications of a constant power source — specifically, sourcing constant power rather than constant voltage or current. I understand it can be useful when the load changes and you want to maintain consistent power consumption, but what are the practical implications of this approach? In which scenarios is it actually preferred or required

[TimFox]

I have seen power supplies for electrophoresis that have constant-power mode, as well as constant-voltage and constant-current.
https://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-gel-electrophoresis/power-supplies-protein-electrophoresis.html

[electroalchemist]

Thanks — yes, that’s exactly what I had in mind as well. It seems the primary application is in heating control, where maintaining constant power helps regulate temperature despite changing loads and prevents potential issues. According to the specs, you can limit the power in 1W increments. Not very high resolution. Perhaps because biological systems are not sensitive to noise or accuracy?!

[ejeffrey]

Constant power supplies are pretty common for plasma sources such as magnetron sputtering supplies.  This helps keep the deposition more uniform as the target is used up.

[electroalchemist]

Thank you. Yes, I believe their minimum output voltage is 500V to 1 kV, with power levels above 1 kW.