An inrush current suppression device is an inrush current suppression device that suppresses an inrush current flowing from a DC power supply through a mechanical switch, and includes: a first capacitor having one end connected to a positive terminal of the DC power supply through the mechanical switch; a semiconductor switching element connected to the other end of the first capacitor and a negative terminal of DC power supply between the other end of the first capacitor and the negative terminal of the DC power supply; a resistance element connected in parallel to the semiconductor switching element; and a control circuit for controlling the semiconductor switching element. The control circuit has a first output port, and controls ON time and OFF time of the semiconductor switching element by outputting a PWM signal from the first output port to the semiconductor switching element after the mechanical switch is closed.

A power conversion system includes: a power converter connected to an alternate-current power supply; a direct-current capacitor connected to a direct-current side of the power converter; a first alternate-current switch connected between the power converter and the alternate-current power supply; an inrush current suppressor connected in parallel to the first alternate-current switch, between the power converter and the alternate-current power supply, and including a charging resistance or a charging reactor; a second alternate-current switch connected in parallel to the first alternate-current switch and in series to the inrush current suppressor, between the power converter and the alternate-current power supply; and a control device configured to control the power converter so that the first alternate-current switch is open, the second alternate-current switch is closed, and a voltage applied to the direct-current capacitor reaches a voltage that is equal to or exceeds a preset voltage.

A power conversion device comprises: a DC link capacitor charged with a DC power supplied from a power supply part; a fuse part, for breaking a current which is output from or supplied to the power supply part and has a first breaking magnitude or greater; a relay part which comprises a first relay for connecting a positive terminal of the fuse part to a positive terminal of the DC link capacitor and a second relay for connecting a negative terminal of the fuse part to a negative terminal of the DC link capacitor; an initial charge part, for charging the DC link capacitor by using DC power supplied from the power supply part; and a power conversion part for converting the direct-current power supplied from the power supply part into AC power when the DC link capacitor has been charged and supplying the alternating-current power to a load terminal.

Techniques are described to slow the turn off of a pass transistor coupled to an inductive load and being controlled by a hot swap or switch controller in the event of a fault on the load side. Active circuitry can control the gate of the pass transistor, e.g., field-effect transistor (FET), as the inductive load de-energizes and a feedback loop can servo the gate voltage of the pass transistor in order to ensure that its source does not go below a reference voltage.

A soft starter includes a plurality of live phases, wherein a semiconductor switching element and an electromechanical switch parallel-connected thereto are arranged in each phase. In the soft starter, on a load-facing side of the semiconductor switching elements and of the electromechanical switches, the plurality of phases are connected in a circuit forming a star point. The star point circuit includes at least one passive component and is configured for detecting a reduced voltage drop in a defective state of a semiconductor switching element and/or of an electromechanical switch.

A system may include a relay device that includes armatures associated with phases of voltage signals. The system may also include relay coils, such that each relay coil may receive a respective voltage that magnetizes a respective relay coil, thereby causing the respective armature to move from a respective first position to a respective second position. The system may also include a control system that receive an indication that a fault condition is present, identify a first phase of the phases of voltage signals that is expected to be the next phase of the phases to cross zero, and send a signal to the relay device in response to identifying the first phase. The signal is configured to cause a first relay coil of the relay coils to energize or deenergize.

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.

A method for suppressing magnetizing inrush current of the transformer with flux linkage control includes connecting a small-capacity direct current/alternating current (DC/AC) converter with the secondary winding or auxiliary winding of transformer, detecting the primary side phase voltage before closing load, inducing the core flux linkage reference according to the relationship between the winding voltage and core flux linkage. The core flux linkage closed-loop PI control system is constructed to control the converter voltage in the synchronous coordinate, then the core flux linkage can track its reference with no static error, thus the sinusoidal flux linkage with 90-degree difference from the grid voltage can be pre-established in the core before no-load closing. By these methods, no matter when the main transformer closes, the core flux linkage is always in the steady state, and the magnetizing inrush current can be eliminated completely.

An apparatus includes a mechanical switch and a solid-state switch, such as a diamond switch or antiparallel-connected thyristor pair, coupled in series between an AC source and the load, such as a substation input transformer. The control circuit may be configured to connect the AC power source to the load by closing the mechanical switch and turning on the solid-state switch thereafter. The control circuit may be configured to interrupt a connection of the AC source to the load by turning off the solid-state switch and closing the mechanical switch thereafter. Operations of the switches may be coordinated with a fuse coupled in series with the solid-state switch to address different types of fault conditions.

(57) Abstract: A system and a method for limiting in-rush currents to a battery module (14) is provided. The system and the method include operating a power MOSFET (12) with a pulse-width-modulated, PWM gate voltage. The frequency and the duty cycle of the PWM gate voltage are iteratively selected such that the current through the battery module (12) does not exceed a current limit value (18), the battery module (14) being series connected with the MOSFET load path. In one embodiment, the frequency and the duty cycle of the PWM gate voltage are alternatively varied to gradually increase the current in the load path until a current limit value (18) is reached.