A transformer arrangement includes a first and a second arrangement side and a transformer with first windings coupled to the first arrangement side and with second windings having a first to a fourth tap. The transformer arrangement comprises a converter coupling the first, second and third tap to the second arrangement side, a first filter circuit coupling the first tap to the third tap and a second filter circuit coupling the third tap to the second tap.

A method and apparatus include a primary transformer coil, a secondary transformer coil, and a center tapped inductor coupled to the secondary transformer coil. A first switch may be in electrical communication with the center tapped inductor and may be configured to affect the first output voltage. A second switch may be in electrical communication with the center tapped inductor and may be configured to affect the second output voltage. In a particular example with an analog current (AC) output voltage, the two output voltages are out of phase to each other. In a direct current (DC) implementation, the transformer may be operated to output a positive and a negative output voltage. The apparatus may function as a resonant converter, or may operate in non-resonant mode. In one implementation, an H bridge may provide reactive power support. An inductor filter may be in electrical communication with the secondary transformer coil. Where desired, a diode bridge may be in electrical communication with the primary transformer coil.

A method and apparatus include a primary transformer coil, a secondary transformer coil, and a center tapped inductor coupled to the secondary transformer coil. A first switch may be in electrical communication with the center tapped inductor and may be configured to affect the first output voltage. A second switch may be in electrical communication with the center tapped inductor and may be configured to affect the second output voltage. In a particular example with an analog current (AC) output voltage, the two output voltages are out of phase to each other. In a direct current (DC) implementation, the transformer may be operated to output a positive and a negative output voltage. The apparatus may function as a resonant converter, or may operate in non-resonant mode. In one implementation, an H bridge may provide reactive power support. An inductor filter may be in electrical communication with the secondary transformer coil. Where desired, a diode bridge may be in electrical communication with the primary transformer coil.

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; a resonant circuit interconnected between the AC input and the AC output. The resonant circuit includes a controllable bypass switch for connecting and disconnecting a circuit input and a circuit output of the resonant circuit and a capacitor and a main inductor connected in parallel with the bypass switch.

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.

A switching device includes a number of line sections corresponding to a number of phases, each including a first and a second connection part, for connection to a connection phase of an electrical consumer. At least one controllable semiconductor switching element is provided per phase, wired between the first and second connection part. A bypass unit includes one controllable electromechanical switching element with a low on-resistance per phase. The controllable electromechanical switching element is wired, in parallel with the controllable semiconductor switching element of this phase, between the first and second connection part. The first and second connection part of a respective phase are arranged adjacently on one side of the power module in spatial proximity in a direction of extent. A contact bridge, assigned to a respective phase, runs in the direction of extent in order to electrically connect the first and second connection part in the switched-on state.

An electronic system sharing power of a doorbell includes a switch circuit and an electronic device. The first and second connection terminals of the switch circuit are respectively coupled to two doorbell contacts. The second and third connection terminals of the switch circuit are respectively coupled to two ends of a doorbell. Two power terminals of the electronic device are respectively coupled to two switch contacts. A function circuit of the electronic device is coupled between the two power terminals. In a normal mode, the first connection terminal is conducted to the second connection terminal inside the switch circuit, and the two power terminals are disconnected from each other by a doorbell actuating unit of the electronic device. In a ringing mode, the doorbell actuating unit short-circuits the two power terminals, and the first connection terminal is conducted to the third connection terminal inside the switch circuit.

A matrix converter system operating in current control mode is provided. The matrix converter includes a switching matrix coupled between a low voltage side and a high voltage side, wherein the matrix converter is coupled at its low voltage side to a generator for receiving an input power including an input current and transforming the input power into an output power at its high voltage side, wherein a load is coupled to the high voltage side. The control system includes a load observer and a model predictive controller (MPC). The load observer is configured to estimate a load current that flows to the load from the high voltage side of the matrix converter as a function of a switching state of the switching matrix, an output voltage output at the high voltage side of the matrix converter, and the input current. The MPC is configured to select the switching state of the switching matrix to meet one or more control objectives defined by minimization of a multi-objective function that tracks the output voltage and the input current using the estimated load current.

A thyristor or triac control circuit includes a first capacitive element that is series-connected with a first diode between a first terminal and a second terminal intended to be coupled to a gate of the thyristor or triac. A second capacitive element is coupled between the second terminal and a third terminal intended to be connected to a conduction terminal of the thyristor or triac on the gate side of the thyristor or triac. A second diode is coupled between the third terminal and a node of connection of the first capacitive element and first diode.

An electronic system sharing power of doorbell includes a switch circuit and an electronic device. The first and second connection terminals of the switch circuit are respectively coupled to two doorbell contacts. The second and third connection terminals of the switch circuit are respectively coupled to two ends of a doorbell. Two power terminals of the electronic device are respectively coupled to two switch contacts. A function circuit of the electronic device is coupled between the two power terminals. In a normal mode, the first connection terminal is conducted to the second connection terminal inside the switch circuit, and the two power terminals are disconnected to each other by a doorbell actuating unit of the electronic device. In a ringing mode, the doorbell actuating unit short-circuits the two power terminals, and the first connection terminal is conducted to the third connection terminal inside the switch circuit.