Systems and methods of monitoring a power system power converter are provided herein. The system includes a plurality of parallel-coupled power converters comprising a power converter input and a power converter output, the power converter output configured to be coupled to a load, each power converter of the plurality of parallel-coupled power converters comprising a power converter controller. The power converter controller is configured to compare an output current of a corresponding power converter to a predetermined output current threshold, monitor the output current for a predetermined time duration when the output current is below the predetermined output current threshold, and shut down the corresponding power converter when the output current is below the predetermined output current threshold for the predetermined time duration.

A DC-DC converter (1) with low start-up power and voltage includes an inductor (3) connected to an input voltage source (2), a switch (11) connected to the inductor and controlled by a controller (10) and a diode (12) connected to a connection node of the inductor and the switch to provide an output voltage (Vout). The controller includes an oscillator and a monostable element, which are powered by the input voltage (Vin). The oscillator provides an oscillation signal (OSC) having a period T of a switching cycle of the switch. The monostable element (103) is controlled by the oscillation signal to determine a duration Tn of conduction of the switch, during which an increasing current (IL) flows through the inductor. The input impedance of the DC-DC converter increases, when the input voltage (Vin) drops below a first voltage threshold with a decreasing duty cycle d=Tn/T.

A power supply system for an electric arc furnace includes an AC input connectable to an electrical grid and an AC output for supplying at least one power electrode of the arc furnace. The power supply system further includes a converter circuit interconnected between the AC input and the AC output. The converter circuit includes at least one converter cell with a capacitor and semiconductor switches for series connecting the capacitor between a circuit input and a circuit output of the converter circuit.

A voltage compensation device according to an embodiment includes a controller including first and second coordinate transformation circuits, and first and second arithmetic parts. The first coordinate transformation circuit generates first and second outputs that are mutually-orthogonal by performing a rotating coordinate transformation of the normal-phase components of a three phase AC. The first arithmetic part calculates a system voltage based on a DC component of the first output and generates a first compensation amount corresponding to a compensation voltage set to compensate a shift of the system voltage from a preset target voltage. The second coordinate transformation circuit generates third and fourth outputs that are mutually-orthogonal by performing a rotating coordinate transformation of reverse-phase components of the three-phase AC. The second arithmetic part generates second compensation amount of a reverse-phase component of the system voltage based on DC components of the third and fourth outputs.

A dimmer is provided for controlling power to a load, the dimmer having a ground leakage power supply deriving power from a connection of the dimmer to ground. The power supply may be a switching-mode power supply that can be the sole or primary power supply to power operation of the dimmer, including operation of the controller.

A voltage-regulating phase-cut dimmable power supply includes an electromagnetic interference filter circuit, a rectifier circuit, a power conversion circuit, a transformer, a rectifier and filter circuit, a phase-cut dimming signal conversion circuit, a first optocoupler, a dimming signal conversion circuit, a voltage comparison control circuit, a second optocoupler, a pulse width modulation (PWM) control circuit, and a voltage sampling circuit. The electromagnetic interference filter circuit, the rectifier circuit, the power conversion circuit, the transformer and the rectifier and filter circuit are electrically connected in sequence. The phase-cut dimming signal conversion circuit, the first optocoupler, the dimming signal conversion circuit, the voltage comparison control circuit, the second optocoupler and the PWM control circuit are electrically connected in sequence to an output end of the electromagnetic interference filter circuit. The voltage sampling circuit is electrically connected to the voltage comparison control circuit and an output end of the rectifier and filter circuit.

A load control device for controlling the amount of power delivered from an AC power source to an electrical load is operable to conduct enough current through a thyristor of a connected dimmer switch to exceed rated latching and holding currents of the thyristor. The load control device comprises a controllable-load circuit operable to conduct a controllable-load current through the thyristor of the dimmer switch. The load control device disables the controllable-load circuit when the phase-control voltage received from the dimmer switch is a reverse phase-control waveform. When the phase-control voltage received from the dimmer switch is a forward phase-control waveform, the load control device is operable to decrease the magnitude of the controllable-load current so as to conduct only enough current as is required in order to exceed rated latching and holding currents of the thyristor.

Techniques for an electronic device to perform power-stealing techniques to harvest energy from a power-control circuit to power components of the electronic device. In some examples, the electronic device may be connected in the power-control circuit between a power supply and a relay that is selectively configured to activate a power load. According to the techniques described herein, the electronic device may include voltage-drop circuitry that is connected in the power-control circuit such that a voltage drop is produced across electrical components of the electronic device while the relay is in the activated, or triggered, state. In this way, the electronic device may perform power-stealing from the power-control circuit while the relay is maintained in the activated state.

A voltage-regulating phase-cut dimmable power supply includes an electromagnetic interference filter circuit, a rectifier circuit, a power conversion circuit, a transformer, a rectifier and filter circuit, a phase-cut dimming signal conversion circuit, a first optocoupler, a dimming signal conversion circuit, a voltage comparison control circuit, a second optocoupler, a pulse width modulation (PWM) control circuit, and a voltage sampling circuit. The electromagnetic interference filter circuit, the rectifier circuit, the power conversion circuit, the transformer and the rectifier and filter circuit are electrically connected in sequence. The phase-cut dimming signal conversion circuit, the first optocoupler, the dimming signal conversion circuit, the voltage comparison control circuit, the second optocoupler and the PWM control circuit are electrically connected in sequence to an output end of the electromagnetic interference filter circuit. The voltage sampling circuit is electrically connected to the voltage comparison control circuit and an output end of the rectifier and filter circuit.

An apparatus for controlling one or more switched high power loads (or heating elements). The apparatus including: one or more switched high power loads (or heating elements), each high power load being powered from a common alternating current power source, and wherein each load is independently switched using a switching signal for zero crossing switching to achieve a desired average power output; the switching signal is generated that comprises a repeated switching sequence; the switching sequence indicates a respective selecting activation for each of the switched high power load over a sequence of half or full cycles.