Any type of power conversion system (e.g. solar inverter, electric drive, UPS, HVDC) requires an auxiliary power supply to provide a low voltage bus of e.g. 12V or 24V to supply gate-drivers, microcontrollers, displays, sensors or fans for proper system operation. The auxiliary power supply will need to operate from either a three-phase 400/480V AC supply in case of typical industrial equipment or a high DC voltage in the case of a photovoltaic inverter.
This is a companion discussion topic for the original entry at https://eepower.com/power-converters/sic-industrial-auxiliary-power-supplies-rohm-semiconductor-gmbh-rohm-semiconductor