A medium-voltage grid-connected photovoltaic inverter system includes: a photovoltaic inverter, a medium-voltage transformer, a medium-voltage switch, and an inverter grid-connected controller. A direct current input terminal of the photovoltaic inverter is connected to a direct current bus. A low-voltage side of the medium-voltage transformer is connected to an alternating current output terminal of the photovoltaic inverter. An input terminal of the medium-voltage switch is connected to a high-voltage side of the medium-voltage transformer, and an output terminal of the medium-voltage switch is configured to be connected to a medium-voltage grid. A current sensor is integrated in the medium-voltage switch to detect a grid-connected current of the photovoltaic inverter system and output a current detection signal.

An alternating current (AC) inverter includes a converter circuit configured to convert a direct current (DC) voltage to an AC voltage, and output terminals, the converter circuit being configured to output the AC voltage to the output terminals. The AC inverter further includes a signal terminal configured to receive a signal from outside of the AC inverter, and a control circuit configured to detect an abnormality related to the AC inverter, control the converter circuit to stop conversion of the DC voltage to the AC voltage in response to detection of the abnormality, and control the converter circuit to resume conversion of DC voltage to the AC voltage in response to reception of the signal on the signal terminal.

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.

Embodiments of this application provide a power conversion circuit, a power transmission system, and a photovoltaic device. The power conversion circuit includes: a first bridge arm, where the first bridge arm includes a first upper bridge arm and a first lower bridge arm; the first upper bridge arm includes a switching component connected between an input positive end and an output end; the first lower bridge arm includes a switching component connected between the output end and an input negative end; each of the switching components includes a switching transistor and a first diode anti-parallel connected to the switching transistor.

An apparatus for switching and/or protection of a load connected to said apparatus, said apparatus (1) comprising: a power switch (5) through which the connected load receives an electrical current; a sensor component (4) connected in series with said power switch (5) and adapted to generate directly an electrical voltage drop corresponding to a current rise speed of the electrical current flowing via the sensor component (4) and via the power switch (5) to said load; and a driver circuit (6) adapted to detect an occurring overcurrent depending on a voltage drop generated by said sensor component (4) with or without a voltage drop along the power switch (5) and to switch off said power switch (5) upon detection of an overcurrent within a switch-off period to protect said power switch (5) and said load.

The present invention relates to a drive control apparatus for an electric motor and a control method thereof. In the present invention, the generation of electric brake is suppressed while protecting a semiconductor relay from excessive surge voltage. The drive control apparatus is configured to include: a drive circuit for controlling the drive of the electric motor; a semiconductor relay arranged on a drive line between the drive circuit and the electric motor to cut off current supply from the drive circuit to the electric motor; and an active clamp circuit for turning on the semiconductor relay when a potential difference between the drive circuit side and the electric motor side of the semiconductor relay is greater than or equal to a predetermined value.

An inverter control device that controls a rotary electric machine drive device that includes an inverter with a plurality of switching elements, where the active short circuit control is executed in a high rotational speed region, and the shut-down control is executed in a low rotational speed region, which is on a low rotational speed side with respect to the high rotational speed region, in accordance with at least a rotational speed of the rotary electric machine.

In a three-level chopper apparatus, a protection switch circuit is controllable to change a current pathway through which an overvoltage is applied to a second capacitor or a first capacitor to a current pathway through which no overvoltage is applied to the second capacitor or the first capacitor.

A protection method in a distributed power system including of DC power sources and multiple power modules which include inputs coupled to the DC power sources. The power modules include outputs coupled in series with one or more other power modules to form a serial string. An inverter is coupled to the serial string. The inverter converts power input from the string and produces output power. When the inverter stops production of the output power, each of the power modules is shut down and thereby the power input to the inverter is ceased.

An air conditioner and a compressor protection circuit thereof are provided. When overcurrent occurs in a phase current of a compressor, an overcurrent level signal is output by a voltage comparison module, and is latched and output to an intelligent power module by a signal latching module, and the intelligent power module shuts off the output of the phase current according to the overcurrent level signal, so as to achieve the overcurrent protection of the compressor; and subsequently, a conventional level signal is output to the signal latching module by the voltage comparison module, the signal latching module keeps outputting the overcurrent level signal, and outputs the conventional level signal until a latching cancel signal output by a signal processing circuit is received, so that the intelligent power module starts the output of the phase current, thereby enabling the compressor to normally operate.