Fault tolerant AC transfer switch

摘要

A redundant power distribution system and method of operation for transferring electrical power from one of several power sources to a load are disclosed. The system comprises one or more copies of a switching circuit with each switching circuit connectable to a power source. Each switching circuit monitors a voltage representative of its power source. The voltage being delivered to the load is also monitored by each switching circuit to detect a failed-open switching circuit. Arbitration is performed among the switching circuits detecting healthy power sources to select one power source to drive the load. Once a switching circuit has won arbitration, it continues to transfer power to the load until its power source fails or the switching circuit itself fails. The hardware can be partitioned in many ways. In one embodiment, two identical switching circuits with redundant hardware functions enable one switching circuit to be removed and replaced without disrupting the load that remains powered through the remaining switching circuit.