A circuit and method for gradually reducing a coil current during a shutdown period is disclosed. The circuit and method include a controller that is configured in a control loop with a current sensor that measures the current in the coil and a transistor that can be controller to limit the current in the coil. The open-loop gain of the controller is determined by a resistance of a variable feedback resistor, and the resistance of the variable feedback resistor is reduced during the shutdown period as the coil current becomes small. The reduction of the resistance maintains a suitable phase margin by lowering the open loop gain of the circuit for low coil currents. Thus, during shutdown, the circuit provides control accuracy for high coil currents and control stability for low coil currents.

A high voltage switch comprising: a high voltage power supply providing power greater than about 5 kV; a control voltage power source; a plurality of switch modules arranged in series with respect to each other each of the plurality of switch modules configured to switch power from the high voltage power supply, and an output configured to output a pulsed output signal having a voltage greater than the rating of any switch of the plurality of switch modules, a pulse width less than 2 s, and at a pulse frequency greater than 10 kHz.

A circuit includes a transistor circuit including a first node, a second node, and a plurality of transistors coupled in parallel between the first node and the second node. The circuit further includes a drive circuit configured to switch on a first group of the plurality of transistors, the first group including a first subgroup and a second subgroup and each of the first subgroup and the second subgroup including one or more of the transistors. The drive circuit is further configured to switch off the first subgroup at the end of a first time period and switch off the second subgroup at a time instant before the end of the first time period.

An AC switching arrangement is provided with an energy transfer arrangement connected in parallel with a switching mechanism. The energy transfer arrangement comprises a capacitance arrangement and a diode arrangement. The switching mechanism normally closed in a first state, and on reception of a signal indicating the second state, the switching mechanism is arranged to open. When the switching mechanism is in the second state, the diode arrangement is arranged in each AC half cycle to enable energy (source energy, stored inductance energy, etc.) to transfer from the grid to the capacitance arrangement but to prevent energy transfer from the capacitance arrangement back to the grid.

A circuit and method for gradually reducing a coil current during a shutdown period is disclosed. The circuit and method include a controller that is configured in a control loop with a current sensor that measures the current in the coil and a transistor that can be controller to limit the current in the coil. The open-loop gain of the controller is determined by a resistance of a variable feedback resistor, and the resistance of the variable feedback resistor is reduced during the shutdown period as the coil current becomes small. The reduction of the resistance maintains a suitable phase margin by lowering the open loop gain of the circuit for low coil currents. Thus during shutdown, the circuit provides control accuracy for high coil currents and control stability for low coil currents.

A DC power switching assembly includes a plurality of series connected power switching units. Each power switching unit has a first terminal of the unit and a second terminal of the unit, the terminals having the same polarity. A power switching sub-unit is electrically coupled between the first terminal and the second terminal of the unit to control current flow between the first terminal and the second terminal. The sub-unit has at least one semiconductor device, a current limiter and a pair of series connected diodes in parallel with the current limiter. The series connected diodes and current limiter are connected to one terminal of the semiconductor device; and a capacitor is connected to the other terminal of the semiconductor device.

A DC power supply system has first and second DC power distribution bus sections and a DC power switching assembly has a plurality of series connected power switching units and a current limiter. Each power switching unit has a first and second power switching unit terminal and two symmetrical power switching sub-units to control current flow between. Each sub-unit is electrically connected on one side to one of the first and second power switching unit terminals and on the other side to the other sub-unit. The power switching sub-units each have a semiconductor device and in parallel with the semiconductor device, a series connected diode and capacitor. A first terminal of the assembly is electrically coupled to the first bus section and the second terminal is electrically coupled to the second bus section. The voltage at one side of the power switching assembly is greater than or equal to 1 kV.

An electric energy storage device which is connected to an electronic circuit is discharged by way of a first and a second electric conductor. A thyristor is provided for discharging the energy storage device. As a result of a fault occurring in the electronic circuit, a discharge current of the energy storage device begins to flow from the energy storage device to the electronic circuit via the first electric conductor and back to the energy storage device via the second electric conductor. The discharge current causes a magnetic field which changes over time to be generated about the first electric conductor and the second electric conductor. The magnetic field penetrates the semiconductor material of the thyristor. By virtue of the temporally varying magnetic field, a current is induced in the semiconductor material of the thyristor, and the thyristor is activated by the induced current.

A semiconductor device according to an embodiment is a semiconductor device including: a first diode having a first anode and a first cathode, the first anode for electrically connecting to one of a first electrode and a second electrode of a semiconductor element including the first electrode, the second electrode, and a gate electrode; a first capacitor having a first end electrically connected to the first cathode, and a first other end; a bias element having a first bias element end electrically connected to the first cathode and the first end, and a second bias element end for electrically connecting to a positive electrode of a direct-current power supply including the positive electrode and a negative electrode; a second diode having a second anode and a second cathode, the second anode electrically connected to the first other end; a second capacitor having a second end and a second other end, the second end electrically connected to the second cathode; a switch electrically connected in parallel to the second capacitor between the second end and the second other end; an analog-digital converter or sample-and-hold circuit electrically connected to the second cathode and the second end; and a third diode having a third anode and a third cathode, the third anode electrically connected to the second other end, and the third cathode electrically connected to the first other end and the second anode.

A device includes a first diode and a second diode connected in series between a first terminal and a second terminal of a switching element, wherein the switching element is a unidirectional device and an anode of the first diode is directly connected to an anode of the second diode, a third diode connected between the first terminal and the second terminal of the switching element and a switch connected in parallel with the first diode.