In one embodiment, an impedance matching network includes at least one electronically variable capacitor (EVC), each EVC comprising discrete capacitors having corresponding switches, the switches configured to switch in and out the discrete capacitors to alter a total capacitance of the EVC. Each switch includes a first terminal operably coupled to the corresponding discrete capacitor, a second terminal, and a switching circuit coupled between the first terminal and the second terminal, the switching circuit comprising a switching transistor. A tuning inductor is coupled parallel to the switching circuit. A value for the tuning inductor enables the tuning inductor to cancel a cumulative parasitic capacitance of the switching circuit.

A power semiconductor module having switching elements includes: a collector main terminal and a collector auxiliary terminal connected to a collector potential of the switching element; a gate auxiliary terminal connected to a gate potential of the switching element; and an emitter main terminal and an emitter auxiliary terminal connected to an emitter potential of the switching element. A power converter includes a voltage dividing circuit board that generates a divided voltage obtained by dividing a voltage between the collector auxiliary terminal and the emitter auxiliary terminal and transmits to a gate driving circuit. The voltage dividing circuit board is electrically connected to the collector auxiliary terminal and the emitter auxiliary terminal. A gate driving circuit changes a driving speed of the switching element according to the divided voltage.

In one embodiment, a parasitic capacitance compensation circuit for a switch is disclosed that includes a first inductor operably coupled between a first terminal and a second terminal, and a second inductor operably coupled between the first and second terminals and parallel to the first inductor. The second inductor is switched in when a peak voltage on the first and second terminals falls below a first voltage. The first inductance tunes out substantially all of a parasitic capacitance of the switch when the switch is OFF and the peak voltage is above the first voltage. The first and second inductances collectively tune out substantially all of the parasitic capacitance of the switch when the switch is OFF and the peak voltage is below the first voltage.

An optocoupler based control circuit and a method thereof are disclosed. The control circuit comprises a first control branch, which includes a first control signal input terminal configured to receive a first OFF function control signal; a first optocoupler, wherein a primary side of the first optocoupler is coupled to the first control signal input terminal, and an output of a secondary side of the first optocoupler is configured to control a first power supplied to a motor driving circuit; a first primary side on/off control circuit connected to the primary side of the first optocoupler, and configured to periodically turn on and off the coupling of the primary side to the first control signal input terminal; and a first secondary side filter circuit connected to the secondary side of the first optocoupler, and configured to filter the output of the secondary side, and configured as a low pass filter having a cutoff frequency lower than an on/off frequency of the primary side. The control circuit further comprises a diagnostic circuit configured to diagnose an operating state of the control circuit based on the output of the secondary side of the first optocoupler and the first power. The control circuit may be a Safe Torque Off (STO) circuit.

In one embodiment, a switching circuit includes a first switch coupled to a first switch terminal, the first switch comprising at least one gallium nitride high-electron mobility transistor (GaN HEMT); a second switch coupled in series with the first switch and a second switch terminal, the second switching comprising a GaN HEMT; and at least one power source configured to provide power to the first switch and the second switch; wherein the second switch is configured to drive the first switch ON and OFF.

The invention discloses a standby control circuit and a display device. The standby control circuit includes a standby module, at least one power board, and a transistor switch control module comprising at least one transistor switch whose number is equal to that of the at least one power board, each transistor switch is connected between one power board and a mains supply input terminal, the standby module is configured to generate a trigger signal and send the generated trigger signal to each transistor switch, and each transistor switch is configured to be turned on upon receipt of the trigger signal sent from the standby module so as to connect the power board connected thereto with the mains supply input terminal.

A power converter includes: a power converter main circuit that includes semiconductor switching elements; gate drive circuits driving the semiconductor switching elements, respectively; and one or a plurality of impedance element groups connected between at least one pair of the gate drive circuits. At least one of the gate drive circuits includes a detector that detects a voltage across the impedance element group, and changes the driving speed of the semiconductor switching elements in accordance with an output of the detector.

An optocoupler is placed in series between the field ground pin of digital input circuitry and the field ground of an industrial controller. A capacitor to field ground is provided for each digital input. A resistor is provided to the input pin of the digital input circuitry. To detect a broken wire a test pulse is provided to the optocoupler connected in the ground path. This test pulse isolates the digital input circuitry from field ground. As current is always being provided from the field when the wire is not broken, the capacitor connected between the input and ground charges. After the test pulse has completed, the output signal of the digital input circuitry is examined. If the level indicates the input is high, the wire is not broken. If, however, the output remains low indicating that the input is low, the wire has broken.

A solar photovoltaic module safety shutdown system includes a module-on switch coupled with a first circuit having a photovoltaic module and a System-Monitor device. The System-Monitor device couples to the module-on switch through a second circuit and to the photovoltaic module and an AC main panelboard through the first circuit. A module-off switch operatively couples with the photovoltaic module and the module-on switch. The System-Monitor device supplies a System-on signal to the module-on switch through the second circuit. The module-on switch disables the photovoltaic module by shorting it or disconnecting it from the first circuit in response to the System-On signal not being received by the module-on switch from the System-Monitor device. The module-off switch disables the photovoltaic module by shorting it in response to the System-On signal not being received by the module-on switch when the photovoltaic module is irradiated with light.

An isolation system and isolation device are disclosed. An illustrative isolation device is disclosed to include first circuitry having at least a first emitter and a first detector, second circuitry having at least a dual-purpose component, an isolation material configured to electrically isolate the first circuitry from the second circuitry, and switching circuitry adapted to connect the dual-purpose component to emit a first signal for detection by the first detector in a first configuration, and to receive a second signal from the first emitter in a second configuration.