A high reliability AC load switching circuit is disclosed. In some embodiments, the AC load switching circuit includes a high-speed switch connected between the load and the voltage source, a cutoff switch connected between the load and the voltage source in parallel with the high-speed switch, and a level detector connected to the voltage source and to a control input of the high-speed switch. The high-speed switch may be a solid-state switch, for example, a TRIAC or a bidirectional switch, and the cutoff switch may be an electromechanical switch, for example, a relay. In some embodiments a snubber is connected in parallel with a solid-state switch. In some embodiments a microcontroller is connected to an eletromechanical switch and the level detector. In some embodiments, both a first cutoff switch and a second cutoff switch are used.

Embodiments of the present invention provide a power supply module and a soft start method. The power supply module includes an input detection circuit configured to output a first notification signal to a trigger drive circuit when it is determined that the power supply module receives a power supply signal; the trigger drive circuit configured to, upon receipt of the first notification signal sent from the input detection circuit, wait for a predetermined duration without sending a drive signal to a current limiting circuit, and to send the driver signal to the current limiting circuit when the predetermined duration elapses; and the current limiting circuit configured to limit a current on a Direct Current (DC) bus of the power supply module when the drive signal is not received by the current limiting circuit, and not to limit the current on the DC bus upon receipt of the drive signal.

An apparatus may include a bus that electrically couples an electrical load to redundant power feeds. The apparatus may also include at least one capacitive component electrically coupled between first and second rails of the bus via both a conductive path and a resistive path that has substantially greater resistance than the conductive path. In addition, the apparatus may include a switching mechanism electrically coupled between the first and second rails of the bus that causes the capacitive component to charge through the conductive path until a threshold voltage on the first rail of the bus is reached. When the threshold voltage on the first rail of the bus is reached, the switching mechanism may close the conductive path and force the capacitive component to charge through the resistive path. Various other systems and methods are also disclosed.

A method and a device for supplying energy to a low-voltage load using an electronic power supply device. The method involves: a) setting the power supply device to be able to provide an output current to the low-voltage load up to a specified peak current value upon demand; b) monitoring the output current (I.sub.L) provided to the low-voltage load by the electronic power supply device to detect an increase of I.sub.L over a threshold (I.sub.N) which is lower than the peak current value, c) if an increase of I.sub.L to an increased output current value higher than I.sub.N is detected, detecting the increased I.sub.L value and ascertaining an output current pulse duration (t.sub.Pulse) based on the increased current value; d) providing I.sub.L at the level of the increased current value for the duration of the ascertained t.sub.Pulse; and e) providing the I.sub.L at the level of I.sub.N after t.sub.Pulse has expired.

A current command value in a period from a time when a relay switch is turned on until charging of an inverter capacitor is completed is set to a value smaller than a value corresponding to the smallest one of rated currents of components included in a circuit, and is set to a value smaller than a maximum current value in a safe operating area of a switching element.

A method includes energizing a transformer from a deenergized state by turning on a solid-state transfer switch to conductively couple a power source on a first side of the solid-state transfer switch and a transformer on a second side of the solid-state transfer switch, and evaluating an inrush current to the transformer from the power source. The method includes turning off the solid-state transfer switch to conductively decouple the power source and the transformer in response to the inrush current meeting a first criterion, determining a recoupling timing for the solid-state transfer switch, and turning on the solid-state transfer switch in response to the recoupling timing effective to complete energization of the transformer with the inrush current to the transformer being limited by the first criterion.

When using DC power supplies, turning off switches and unplugging from sockets can result in arc discharge, and when arc discharge occurs, heat is generated, which can cause damage to contacts, wiring of disconnection points to melt, and fires. In order to solve this problem, an object is to prevent inrush current when connecting a power supply, detect arc discharge generated when disconnecting direct current, and stop arc discharge over a short period of time. All of the loads that are connected to a DC power supply are equipped with a soft-start function that gradually and smoothly increases current so as to prevent current from flowing suddenly when connected to a power supply, and if a sudden drop in the power supply voltage is detected, an arc discharge is deemed to have occurred, and the flow of current from the power supply to the load is cut off immediately.

A control circuit is provided. The control circuit includes a load switch, and a controller configured to transfer a turn-on signal which is increased step by step to the load switch, and perform a soft start operation which turns on the load switch. In response to the load switch being turned on, the control circuit restricts an inrush current flowing in the load switch.

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.

Precharging systems and methods are presented for precharging a DC bus circuit in a power conversion system, in which precharging current is connected through a precharging resistance coupled between only a single AC input line and the DC bus circuit when the DC bus voltage is less than a non-zero threshold, and a controller individually activates controllable rectifier switching devices when the DC bus voltages greater than or equal to the threshold using DC gating or pulse width modulation to selectively provide a bypass path around the precharging resistance for normal load currents in the power conversion system.