A regulated dc power supply having master and slave regulators

Claim 1

A regulated DC power supply system comprising: a plurality of switching regulators (21,23,25), including a master regulator (21) and plural slave regulators (23,25), connected in parallel in a redundant configuration of N+1 regulators to provide an output current to a load (62); each of the regulators (21,23,25) providing a substantially equal share of the output current to the load (62); and each regulator (21) including a current mode control circuit (27) having a feedback loop from the load (62) for comparing the output current to the load (62) with a predetermined reference to generate an error signal; characterised in that each slave regulator (23) further comprises a steering circuit (61) for connecting the slave regulator (23) to the error signal from the master regulator (21) when the error signal from the master regulator (21) is between upper and lower limits and for connecting the slave regulator (23) to the error signal generated by its own control circuit (65) when the error signal from the master regulator (21) is outside the upper and lower limits, thereby transferring control, in response to the failure of the master regulator (21) to the slave regulators (23,25) while maintaining a stable output to the load.