In general, according to one embodiment, a protection circuit includes first and second power lines, first and second controllers, a first transistor, and a detector. The first controller includes a first resistor element, a capacitor, first, second, and third inverters. The second controller includes third transistor. One end of the third transistor is coupled to the second power line. The other end of the third transistor is coupled to each of the output end of the first inverter and the input end of the second inverter.

In general, according to one embodiment, a protection circuit includes first and second power lines, first and second controllers, a first transistor, and a detector. The first controller includes a first resistor element, a capacitor, first, second, and third inverters. The second controller includes third transistor. One end of the third transistor is coupled to the second power line. The other end of the third transistor is coupled to each of the output end of the first inverter and the input end of the second inverter.

An electrical system forming part of a solar power plant is described. The electrical system includes a plurality of photovoltaic (PV) panels, a power converter, and a controller. In response to a detected electric arc on the DC side of the power converter, the controller is configured to enable a short circuit state of the power converter by controlling semiconductor switches of the power converter (e.g., turning on some or all of the semiconductor switches) to create a short circuit between DC input terminals of the power converter. The short circuit path though the power converter will extinguish the detected electric arc in the connected DC circuit.

A short-circuit protection apparatus includes a first detection branch, a second detection branch, and a controller. The first detection branch includes a first sampling resistor and a first sampling capacitor that is connected in parallel to the first sampling resistor. A difference between an absolute value of a second sampling voltage and an absolute value of a first sampling voltage is a first difference. The controller obtains a comparison result between an absolute value of a first sampling voltage at two terminals of the first sampling resistor and an absolute value of a second sampling voltage at two terminals of the second sampling resistor, and if a difference between the absolute value of the second sampling voltage and the absolute value of the first sampling voltage is a second difference and the second difference is less than the first difference, controls the target circuit to stop working.

A photovoltaic system, an inverter, and a direct current electric arc detection method. The system includes an inverter, a controller, and at least two converters. When detecting an electric arc, the controller controls an input current of the inverter to decrease to extinguish the arc. After the arc is extinguished, the controller controls an output voltage of at least one photovoltaic string to decrease to a first preset voltage, where the first preset voltage is less than an input voltage of the inverter when the electric arc is detected, or controls a maximum value of an output current of the at least one photovoltaic string to be a second preset current, where the second preset current is less than the input current of the inverter when the electric arc is detected. In the foregoing two recovery manners, no electric arc recurs.

Methods, systems, and devices for protecting a wireless power transfer system. One aspect features a sensor network for a wireless power transfer system. The sensor network includes a differential voltage sensing circuit and a current sensing circuit. The differential voltage sensing circuit is arranged within a wireless power transfer system to measure a rate of change of a voltage difference between portions of an impedance matching network and generate a first signal representing the rate of change of the voltage difference. The current sensing circuit is coupled to the differential voltage sensing circuit and configured to calculate, based on the first signal, a current through a resonator coil coupled to the wireless power transfer system.

Methods, systems, and devices for protecting a wireless power transfer system. One aspect features a sensor network for a wireless power transfer system. The sensor network includes a differential voltage sensing circuit and a current sensing circuit. The differential voltage sensing circuit is arranged within a wireless power transfer system to measure a rate of change of a voltage difference between portions of an impedance matching network and generate a first signal representing the rate of change of the voltage difference. The current sensing circuit is coupled to the differential voltage sensing circuit and configured to calculate, based on the first signal, a current through a resonator coil coupled to the wireless power transfer system.

A circuit for minimizing energy provided to a ground fault includes a source, a multiple switches, an output filter, and a controller. The switches include a first side pair of switches and a second side pair of switches configured to provide an output signal based on the source. The output filter includes one or more energy storage elements coupled to the first side pair of switches or the second side pair of switches. The controller is configured to receive a ground fault signal that indicates a fault has occurred and configured to generate a switch signal for the switches for a minimum energy state of the output filter and in response to the ground fault signal.

A solid-state fuse device includes a switch a gate driver connected to the switch and configured to transition the switch from a closed state to an open state when at least one of an overcurrent measurement exceeds a predetermined overcurrent threshold or a voltage drop across the switch exceeds a predetermined saturation voltage threshold.

A threshold detection system can be configured to monitor a location (e.g., a DC link) for overcurrent. The threshold detection system can be configured to generate a pulse width modulated signal with a duty cycle that is proportional to current through the DC link. The threshold detection system can be configured to determine whether the duty cycle exceeds a selected threshold.