Abstract: A modular power supply system (10) is provided for providing a multiplicity of output voltages from a plurality of respective converter modules (70a-70n). Each of the converter modules (70a-70n) has an input coupled to a DC high voltage bus (22) from which a respective output voltage is generated. The voltage supplied on DC bus (22) is generated by a power factor corrected boost converter circuit (20) which is coupled to an AC input source (12). Further, a battery backup module (40) is coupled to the high voltage DC bus (22) for supplying backup power whenever the bus voltage drops below a predetermined level.