Patent ID: 7965526

Claim:
A switch circuit for selectively controlling conduction of current between first and second circuit nodes of a power converter, the switch circuit comprising: a switching device having first and second switch terminals coupled with the first and second circuit nodes, respectively, or multiple switching devices in a series-connection having the first and last terminals coupled with the first and second circuit nodes respectively, and a control terminal for each switching device receiving a switching signal to selectively operate the switching device in one of a conductive state and a nonconductive state for controlling the conduction of current between first and second circuit nodes; a switch driver having an output terminal coupled with the control terminal of the switching device and at least one power terminal for receiving power, the switch driver being operative to provide the switching signal according to a received switch control signal using power from the at least one power terminal; a snubber circuit having a snubber storage device and first and second snubber terminals coupled with anode and cathode nodes of the switching device or switching devices; a supply circuit forming a series circuit with the snubber circuit between the cathode and anode nodes in parallel with the switching device or devices, the supply circuit comprising: a first converter circuit with a full bridge rectifier coupled to the snubber circuit, a supply storage device coupled with a first DC bus created by the rectifier, and a shunt coupled with the full bridge rectifier to sense a snubber current, and a second converter circuit with an isolated DC to DC converter receiving the first DC bus and providing an isolated main DC output to provide electrical power to the switch driver for operation of the switch driver; and a diagnostic circuit operatively coupled with the first converter circuit to monitor the first DC bus and with the second converter circuit to monitor the main DC output, wherein the diagnostic circuit is operatively coupled with the shunt to monitor the snubber current.