A power conversion circuit having a solid-state circuit breaker integrated therein is disclosed. With a disconnect switch between a utility source and the power conversion apparatus described for meeting UL489, the power conversion circuit includes an input connectable to an AC source, a rectifier circuit connected to the input to convert an AC power input to a DC power, and a DC link coupled to the rectifier circuit to receive the DC power therefrom. The rectifier circuit comprises a plurality of phase legs each including thereon an upper switching unit and a lower switching unit, wherein at least one of the upper and lower switching units on each phase leg comprises a bi-directional switching unit that selectively controls current and withstands voltage in both directions, so as to provide a circuit breaking capability that selectively interrupts current flow through the rectifier circuit, while maintaining original power conversion functionalities.

A power supply includes a power converter, a protection circuit, and a control circuit. The protection circuit includes an input for receiving an input voltage, an output for providing an output voltage to the power converter, a first switching device coupled in a current path between the input and the output, and a second switching device coupled across the first switching device. The control circuit is configured to sense the input voltage and the output voltage, in response to the output voltage exceeding a first defined threshold, turn off the first switching device and turn on the second switching device to supply power to the power converter, and in response to the input voltage exceeding a second defined threshold, turn off the second switching device to disconnect the power source from the power converter. Other example power supplies and protection circuits are also disclosed.

The present disclosure provides exemplary embodiments of voltage harvesting devices used in power distribution systems, and provides power distribution system architectures utilizing the voltage harvesting devices. Generally, the voltage harvesting devices transform distribution line AC voltages to produce a low wattage output for distribution system communication and control type devices. The voltage harvesting device can operate whether irrespective of the presence of load current.

The present disclosure provides exemplary embodiments of voltage harvesting devices used in power distribution systems, and provides power distribution system architectures utilizing the voltage harvesting devices. Generally, the voltage harvesting devices transform distribution line AC voltages to produce a low wattage output for distribution system communication and control type devices. The voltage harvesting device can operate whether irrespective of the presence of load current.

A modular multilevel converter includes a plurality of submodules, each having at least two electronic switching elements, an electric energy store, two submodule connections, a bypass switch bridging the submodule, and a communication element communicating with a communication apparatus. A method for operating the modular multilevel converter includes ascertaining that the submodules have a defective submodule so that the communication element in the defective submodule does not communicate with the communication apparatus, determining whether a present arm current resulting from an operating point of the modular multilevel converter is below a predetermined threshold value, and generating or amplifying a converter-internal circular current with the defective submodule if the arm current resulting from the operating point is below the predetermined threshold value. A modular multilevel converter is also provided.

A modular multilevel converter includes a plurality of submodules, each having at least two electronic switching elements, an electric energy store, two submodule connections, a bypass switch bridging the submodule, and a communication element communicating with a communication apparatus. A method for operating the modular multilevel converter includes ascertaining that the submodules have a defective submodule so that the communication element in the defective submodule does not communicate with the communication apparatus, determining whether a present arm current resulting from an operating point of the modular multilevel converter is below a predetermined threshold value, and generating or amplifying a converter-internal circular current with the defective submodule if the arm current resulting from the operating point is below the predetermined threshold value. A modular multilevel converter is also provided.

A high voltage DC (HVDC) system can include a generator configured to output alternating current (AC), a rectifier connected to the generator via AC phase lines, the rectifier configured to convert the AC to DC to output the DC to DC feeder lines, and a crowbar system. The crowbar system can include a switch module operatively connected to the AC phase lines to prevent AC from flowing to the rectifier in a cutoff state. The crowbar system can be configured to determine whether at least one cutoff condition exists. The at least one cutoff condition can be or include one or more of a DC overcurrent downstream of the rectifier, a DC overvoltage downstream of the rectifier, an AC overcurrent from the generator, or an arc fault. The crowbar system can be configured to control the switch module to the cutoff state if the at least one cutoff condition exists.

A high voltage DC (HVDC) system can include a generator configured to output alternating current (AC), a rectifier connected to the generator via AC phase lines, the rectifier configured to convert the AC to DC to output the DC to DC feeder lines, and a crowbar system. The crowbar system can include a switch module operatively connected to the AC phase lines to prevent AC from flowing to the rectifier in a cutoff state. The crowbar system can be configured to determine whether at least one cutoff condition exists. The at least one cutoff condition can be or include one or more of a DC overcurrent downstream of the rectifier, a DC overvoltage downstream of the rectifier, an AC overcurrent from the generator, or an arc fault. The crowbar system can be configured to control the switch module to the cutoff state if the at least one cutoff condition exists.

An isolated synchronous rectification type DC/DC converter, includes: a transformer including primary and secondary windings; a switching transistor connected to the primary winding; a synchronous rectifying transistor installed between the secondary winding and a ground line on the secondary side; a photocoupler including a light emitting device and a light receiving device; a feedback circuit driving the light emitting device such that an output voltage of the DC/DC converter approaches a target voltage; a primary side controller connected to the light receiving device and switching the switching transistor depending on feedback signal from the photocoupler; a synchronous rectification controller controlling the rectifying transistor; and a protection circuit including a temperature detection element, one end of the detection element connected to a drain of the rectifying transistor, the protection circuit configured to detect an overheated state of the rectifying transistor depending on a first signal generated by the temperature detection element.

An isolated synchronous rectification type DC/DC converter, includes: a transformer including primary and secondary windings; a switching transistor connected to the primary winding; a synchronous rectifying transistor installed between the secondary winding and a ground line on the secondary side; a photocoupler including a light emitting device and a light receiving device; a feedback circuit driving the light emitting device such that an output voltage of the DC/DC converter approaches a target voltage; a primary side controller connected to the light receiving device and switching the switching transistor depending on feedback signal from the photocoupler; a synchronous rectification controller controlling the rectifying transistor; and a protection circuit including a temperature detection element, one end of the detection element connected to a drain of the rectifying transistor, the protection circuit configured to detect an overheated state of the rectifying transistor depending on a first signal generated by the temperature detection element.