A continuous power supply system suitable for input connection to N continuous power supply networks that are distinct and connected to a single ground potential, where N is an integer greater than or equal to 2. Said continuous power supply system comprises means for switching/selecting one of the power supply networks, means for regulating an output voltage established by the power supply system, and a control unit for the means for switching/selecting and for the means for regulating. The means for regulating the output voltage includes N distinct buck-boost converters with shared inductance. A given buck-boost converter is dedicated to each power supply network for regulating the voltage output of the power supply system on the basis of an input voltage established by the corresponding power supply network.