Patent ID: 7787222

Claim:
A protection circuit for a parallel power system comprising a plurality of multi-phase voltage regulator modules (VRMs), each multi-phase voltage regulator module comprising a plurality of voltage regulators, wherein the plurality of multi-phase voltage regulator modules are parallel coupled, the protection circuit comprising: at least two separate isolation control circuits, each separate isolation control circuit being coupled to a different multi-phase voltage regulator module of the plurality of multi-phase voltage regulator modules of the parallel power system, wherein each multi-phase voltage regulator module regulates voltage across multiple phases of the parallel power system and each separate isolation control circuit coupled to a different multi-phase voltage regulator module comprises: a current sense circuit for sensing current polarity at an output of the respective multi-phase voltage regulator module; and a controller coupled to the current sense circuit for automatically isolating the respective multi-phase voltage regulator module when both an over-voltage condition exists at an output of the parallel power system and a positive current polarity is sensed at the output of the respective multi-phase voltage regulator module, wherein the at least two isolation control circuits of the protection circuit isolate only a multi-phase voltage regulator module sourcing current during the over-voltage condition, while another multi-phase voltage regulator module of the plurality of multi-phase voltage regulator modules sinking current during the over-voltage condition remains operational during the over-voltage condition.