A switched-mode power supply has a rectifier device, a switching unit which is arranged downstream of the rectifier device, a transmission device which is arranged downstream of the switching unit and a filter device. In order to reduce the sensitivity of the switched-mode power supply to high-energy interferences, it is proposed that the filter device contains a current-compensated choke coil which is connected to a voltage limiter circuit in such a way that in the case of interference signals applied to the choke coil, a damping of the interference signals takes place by way of the voltage limiter circuit.

In accordance with an embodiment, a method for electrostatic discharge (ESD) protection includes: dividing a voltage between a plurality of circuit nodes using a voltage divider circuit to form a divided voltage; compensating a temperature dependency of the divided voltage to form a temperature compensated divided voltage; monitoring the voltage between the plurality of circuit nodes using a transient detection circuit to form a transient detection signal; and activating a clamp circuit coupled between the plurality of circuit nodes based on the temperature compensated divided voltage and based on the transient detection signal.

A fast-operating AC fault current limiter, to limit the fault current let through to downstream equipment during short circuit or low-impedance faults, comprises a series inductor to limit current rise time, a current sensor to sense the instantaneous current, a series AC semiconductor switch to interrupt current flow when it exceeds the maximum desired fault current, and a shunt AC semiconductor switch to catch inductor flyback voltage when the series semiconductor switch is opened. Each of the series and the shunt AC switches comprises two back-to-back MOSFETs. Inventive control of timing of the individual MOSFETs obviates the need for exact simultaneous timing of opening the series switch and closing the shunt switch, which is otherwise required to avoid short circuits.

In accordance with an embodiment, a method for electrostatic discharge (ESD) protection includes: dividing a voltage between a plurality of circuit nodes using a voltage divider circuit to form a divided voltage; compensating a temperature dependency of the divided voltage to form a temperature compensated divided voltage; monitoring the voltage between the plurality of circuit nodes using a transient detection circuit to form a transient detection signal; and activating a clamp circuit coupled between the plurality of circuit nodes based on the temperature compensated divided voltage and based on the transient detection signal.

A system for connecting first and second high voltage direct current (HVDC) sources in parallel to a bus includes one or more contactors connecting the first HVDC source to the bus. The system also includes a bus coupling circuit located between the second HVDC source and the bus that utilizes inductors to couple, in operation, couples the second HVDC source to the bus such that first and second HVDC sources are in parallel with the second positive output is connected to the positive rail and the second negative output connected to the negative rail. The inductors are first connected to the bus though auxiliary contactors and, after a predetermined time, main contactors are closed that provide a path around the inductors.

A power supply device includes a spike absorption circuit that suppresses an avalanche breakage of a current shutdown switch due to a kickback voltage that may appear in response to the cut-off of a load current. The current shutdown switch is connected to secondary batteries. The spike absorption circuit is a series circuit of a protection switch, formed of a semiconductor element, and a diode. The power supply device further includes: a small-signal switch that controls turn-on and turn-off of the protection switch; and a delay circuit that maintains the small-signal switch in an ON state over a setup time after a current shutdown timing of the current shutdown switch. The delay circuit maintains the small-signal switch in the ON state over the setup time (T), and the small-signal switch thereby causes the protection switch to the ON state. Then, the spike absorption circuit damps the kickback voltage.

An AC-AC power converter, such as a motor soft starter, includes an input connectable to an AC source with a disconnect switch, an output connectable to an AC load, and phase lines connecting the input and output to transmit power. In-line solid-state switching blocks are connected between line terminals and load terminals of the AC source and AC load, respectively, such that each phase line includes a solid-state switching block connected thereto. Free-wheeling solid-state switching blocks are connected to the load terminals at one end and together at a common connection at another end, such that each phase line includes a free-wheeling solid-state switching block connected thereto. Each of the in-line and free-wheeling solid-state switching blocks comprises a bi-directional switching block that selectively controls current and withstands voltage in both directions. The switching blocks also provide soft-starter functions, variable speed control, and integrated circuit breaker protection capability.

Certain aspects of the present disclosure provide a voltage transient detection circuit. The circuit generally includes a first switch having a first terminal coupled to an input signal source node, and a second switch having a first terminal coupled to the input signal source node. The apparatus includes a first shunt capacitive element coupled to a second terminal of the first switch, a second shunt capacitive element coupled to a second terminal of the second switch, a differential circuit having a first input coupled to the second terminal of the first switch, a second input coupled to the second terminal of the second switch, and an output coupled to an output node of the voltage transient detection circuit. For certain aspects, the apparatus also includes a first current source (selectively) coupled to the first shunt capacitive element and a second current source (selectively) coupled to the second shunt capacitive element.

A system for connecting first and second high voltage direct current (HVDC) sources in parallel to a bus includes one or more contactors connecting the first HVDC source to the bus. The system also includes a bus coupling circuit located between the second HVDC source and the bus that utilizes inductors to couple, in operation, couples the second HVDC source to the bus such that first and second HVDC sources are in parallel with the second positive output is connected to the positive rail and the second negative output connected to the negative rail. The inductors are first connected to the bus though auxiliary contactors and, after a predetermined time, main contactors are closed that provide a path around the inductors.

A measuring device is provided. The measuring device includes a sensor unit configured to detect a measurement signal, upstream measuring device electronics that include a signal processing circuit and an input interface, and a power limitation circuit arranged to limit the power supplied by the external power supply at the input interface.