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 power converter for heat tracing applications is disclosed. The power converter includes a controller configured to control an input switching stage. The power converter also includes an output filter, the output filter electrically coupled to the input switching stage. Further, the power converter includes a passive cooling element, the passive cooling element coupled to the power converter. The controller is configured to select a peak voltage and set a power converter output voltage based on at least one of the peak voltage and a power converter input voltage. The passive cooling element is configured to decrease a temperature of the power converter and to obviate the need for cooling with moving parts, making the system viable for hazardous areas in addition to non-hazardous areas. The input switching stage includes a plurality of transistors. The power converter output voltage and the power converter input voltage are both alternating current.

A load control device for controlling power delivered from an AC power source to an electrical load includes a thyristor, a gate coupling circuit for conducting current through a gate terminal of the thyristor, a controllable switching circuit coupled between first and second main terminals of the thyristor, and a control circuit for controlling the gate coupling circuit to conduct a pulse of current through the gate terminal to render the thyristor conductive at a firing time during a half cycle. The gate coupling circuit is able to conduct at least one other pulse of current through the gate terminal after the firing time until a transition time before an end of the half-cycle. The control circuit is configured to render the controllable switching circuit conductive to conduct current through the electrical load between approximately the transition time until approximately the end of the half-cycle.

An electronic system and method include a controller to actively control power transfer from a primary winding of a switching power converter to an auxiliary-winding of an auxiliary power supply. The switching power converter is controlled and configured such that during transfer of power to the auxiliary-winding, the switching power converter does not transfer charge to one or more secondary-windings of the switching power converter. Thus, the switching power converter isolates one or more secondary transformer winding currents from an auxiliary-winding current. By isolating the charge delivered to the one or more secondary-windings from charge delivered to the auxiliary-winding, the controller can accurately determine an amount of charge delivered to the secondary-windings and, thus, to a load.

In accordance with one or more embodiments, a monostable multivibrator that is communicatively coupled to a host device and an external analog-to-digital converter is provided. The monostable multivibrator receives a chip select signal from the host device. The monostable multivibrator also generates, in response to the chip select signal, a conversion start signal to the external analog-to-digital converter.

A Voltage Source Converter control system for active damping of a resonance oscillation in the VSC includes a regular Phase-Locked Loop 2, and a slow PLL 3. The control system is arranged such that an imaginary part of the AD is obtainable from the slow PLL. The slow PLL is configured for having a closed-loop bandwidth which is less than a frequency, in a synchronous dq frame, of the resonance oscillation to be dampened.

A transformer arrangement comprising a transformer having a primary side for receiving input voltage and current from a source and a secondary side for providing output voltage and current to a load. The transformer arrangement further comprises an AC-AC PE converter connected to a thyristor used for bypassing the AC-AC PE converter in case of a short-circuit fault in a terminal of the primary side and/or the secondary side. The transformer arrangement further comprises a thyristor-based AC-AC PE converter connected to a thyristor-tapped winding. The AC-AC PE converter is connected with the thyristor-tapped winding via the thyristor-based AC-AC PE converter. The thyristor-based AC-AC PE converter is connected to an impedance to protect the thyristor-tapped winding from short-circuit faults of the thyristor-based AC-AC PE converter.

A transformer arrangement comprising a transformer having a primary side for receiving input voltage and current from a source and a secondary side for providing output voltage and current to a load. The transformer arrangement further comprises an AC-AC PE converter connected to a thyristor used for bypassing the AC-AC PE converter in case of a short-circuit fault in a terminal of the primary side and/or the secondary side. The transformer arrangement further comprises a thyristor-based AC-AC PE converter connected to a thyristor-tapped winding. The AC-AC PE converter is connected with the thyristor-tapped winding via the thyristor-based AC-AC PE converter. The thyristor-based AC-AC PE converter is connected to an impedance to protect the thyristor-tapped winding from short-circuit faults of the thyristor-based AC-AC PE converter.

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.