A symmetry control circuit for a trailing edge phase control dimmer circuit for controlling alternating current (AC) power to a load, the symmetry control circuit including: a bias signal generator circuit configured to monitor non-conduction periods of each half cycle of said AC power for an elapsed duration of the non-conduction periods, and generate a bias signal voltage based on the elapsed duration, whereby an amplitude of the bias signal voltage is proportional to the elapsed duration of the non-conduction periods; and a bias signal converter circuit configured to convert the bias signal voltage to a bias signal current, wherein the bias signal current is added to a reference current of a conduction period timing circuit configured to determine said conduction periods, and wherein the conduction period timing circuit is configured to alter one of the conduction periods immediately following one of the non-conduction periods based on the bias signal current when added to the reference current to compensate for a phase shift of a zero-crossing of said one of the non-conduction periods corresponding to an elapsed duration of said one of the non-conduction periods so as to restore symmetry of the non-conduction periods of each half cycle of AC power.

A transformer device and a control method for the transformer device are provided. The transformer device includes a transformer, an uplink cascade connection port, a downlink cascade connection port, and a controller. The controller is enabled when the transformer receives an input electric power, and the controller determines whether the uplink cascade connection port is connected to an uplink transformer device. When the uplink cascade connection port is connected to the uplink transformer device, the controller detects a downlink external transformer device connected to the downlink cascade connection port, reports a detection result to the uplink transformer device, and obtains a control signal from the uplink cascade connection port. The controller converts the input electric power into an output electric power according to the control signal and the transformer.

A load control device for controlling the power delivered from an AC power source to an electrical load includes a thyristor, a gate coupling circuit for conducting a gate current through a gate of the thyristor, and a control circuit for controlling the gate coupling circuit to conduct the gate current through a first current path to render the thyristor conductive at a firing time during a half cycle. The gate coupling circuit is able to conduct the gate current through the first current path again after the firing time, but the gate current is not able to be conducted through the gate from a transition time before the end of the half-cycle until approximately the end of the half-cycle. The load current is able to be conducted through a second current path to the electrical load after the transition time until approximately the end of the half-cycle.

Disclosed is an alternating current conversion circuit including an AC input end, an AC output end, an intelligent conversion circuit, a voltage sampling circuit and a master control circuit. The intelligent conversion circuit is configured to output a standard voltage inputted by the AC input end to the AC output end, and convert a non-standard voltage inputted by the AC input end into a standard voltage and output the standard voltage converted to the AC output end, under the control of the master control circuit. The voltage sampling circuit is configured to sample the voltage inputted by the AC input end and the voltage outputted by the intelligent conversion circuit. The invention provides an intelligent AC conversion, allowing the electronic devices which are designed for a single power grid to be adapted to various power grids.

The present disclosure relates to a control circuit of a triac or thyristor having its driving reference terminal connected to a first reference node and coupled to a voltage rectifier comprising at least a semiconductor device connected between the first reference node and a second reference node of the control circuit comprising: a first bipolar transistor; and a driving circuit of the first transistor referenced to the second reference node.

A static synchronous compensator device connected between a source and a load of a three-phase power system, comprising: a main feedback line configured to provide a main feedback signal from lines between the source and the load; a mixer configured to mix the main feedback signal with a balance function to generate a balanced signal; a signal controller configured to convert the balanced signal to a controlled signal; a gain circuit configured to multiply the controlled signal by 1 and to perform proportional gain and integral gain (P & I) processing on the controlled signal to generate an intermediate correction signal; and a pulse width modulator configured to apply a pulse width modulation pattern to modulate the voltage source inverter to generate an AC waveform that is applied to the lines between the source and the load.

A portable power converter includes a housing having a front surface and a rear surface, a socket disposed on the front surface and configured to conduct an input waveform, and a plug disposed on the rear surface and configured to conduct an output waveform. The power converter also includes a power conversion circuit disposed within the housing and coupled to the socket and the plug. The power conversion circuit includes a low power conversion circuit coupled to the socket and configured to transform the input waveform into a first waveform, a high power conversion circuit coupled to the socket and configured to transform the input waveform into a second waveform, and a switch circuit coupled to the low power conversion circuit and the high power conversion circuit. The switch circuit is configured to combine the first waveform and the second waveform to generate the output waveform.

A portable power converter includes a housing having a front surface and a rear surface, a socket disposed on the front surface and configured to conduct an input waveform, and a plug disposed on the rear surface and configured to conduct an output waveform. The power converter also includes a power conversion circuit disposed within the housing and coupled to the socket and the plug. The power conversion circuit includes a low power conversion circuit coupled to the socket and configured to transform the input waveform into a first waveform, a high power conversion circuit coupled to the socket and configured to transform the input waveform into a second waveform, and a switch circuit coupled to the low power conversion circuit and the high power conversion circuit. The switch circuit is configured to combine the first waveform and the second waveform to generate the output waveform.

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.

A load control device for controlling power delivered from an AC power source to an electrical load includes a thyristor, a first current path for conducting current through a gate terminal of the thyristor, and a control circuit for controlling the first current path to conduct a pulse of current through the gate terminal to render the thyristor conductive at a firing time during a present half cycle. The first current path is able to conduct at least one other pulse of current through the gate terminal between the firing time, and a second time that occurs before an end of the present half-cycle, but is prevented from conducting pulses of current between the second time and the end of the present half-cycle. The load control device includes a second current path for conducting current through the electrical load if the thyristor becomes and remains non-conductive during the present half-cycle.