An electronic transformer including a controller and a dimming control circuit. The controller is configured to control an output voltage. The dimming control circuit is configured to receive a user-input and output a control signal based on the user-input. The controller varies the output voltage based on the control signal. Wherein the output voltage is substantially the same regardless of an amplitude of an input voltage.

Control of a resonant power converter using switch paths during power-up is described herein. During power-up, a first switch path sinks current away from a resonant capacitor while a second switch path sources current to a high-side capacitor. In this way the high-side capacitor may predictably charge to sufficient bootstrap voltage for steady state operation. Additionally, a third switch path may control current to a low-side capacitor.

An integrated circuit for a power supply circuit including a transformer having a primary coil, a secondary coil, and an auxiliary coil, and a transistor configured to control a current flowing through the primary coil. The integrated circuit includes a first terminal receiving a power supply voltage corresponding to a voltage from the auxiliary coil; a second terminal receiving a feedback voltage corresponding to an output voltage; a third terminal receiving a voltage corresponding to a current flowing through the transistor when the transistor is on; a determination circuit determining whether a detection circuit configured to detect a voltage generated in the auxiliary coil is coupled between the third terminal and the auxiliary coil; and a switching control circuit controlling switching of the transistor based on the voltages at the second and third terminals and a determination result of the first determination circuit.

An energy harvesting circuit for harvesting energy from a medium voltage power line. The energy harvesting circuit includes an input capacitor electrically coupled to the power line and storing power therefrom, and a flyback converter including a primary coil and a secondary coil. The harvesting circuit further includes a switching circuit electrically coupled in series with the primary coil and being operable to electrically connect and disconnect the input capacitor to and from the primary coil, where the switching circuit includes an input voltage regulation feedback circuit for regulating an input voltage provided to the switching circuit from the input capacitor. The harvesting circuit also includes an output capacitor electrically coupled to the secondary coil and the actuator, where the output capacitor is charged by the secondary coil when the switching circuit is closed to provide power to an actuator to close a vacuum interrupter.

An auxiliary power supply device for an inverter with a plurality of power modules connected in parallel is disclosed. The auxiliary power supply device includes: a plurality of soft-start circuits, each coupled to a DC port of a corresponding power module; a plurality of distributed auxiliary power supplies, each having an input terminal coupled to the DC port of the corresponding power module; and a centralized auxiliary power supply having an input terminal coupled to an AC side of the inverter, and an output terminal coupled to a DC side of the inverter. By replacing auxiliary power supplies on the AC sides of all power modules with the centralized auxiliary power supply and omitting soft-start circuits on the AC sides of all power modules, the present invention improves system performance in cost, volume, loss, and electromagnetic compatibility.

Disclosed herein is a power supply apparatus for a sub-module controller of a Modular Multilevel Converter (MMC), which supplies driving power to the sub-module controller of an MMC connected to a High Voltage Direct Current (HVDC) system. The power supply apparatus includes a bridge circuit unit including N (N≧2, integer) energy storage units for storing a DC voltage in series-connected sub-modules in the MMC and multiple power semiconductor devices connected in parallel with the N energy storage units in a form of a bridge; and a DC/DC converter for converting a voltage output from output terminals formed between both ends of n (1≦n<N) series-connected energy storage units, among the N energy storage units, into a low voltage and supplying the low voltage to the sub-module controller.

Disclosed herein is a power control apparatus for sub-modules in an MMC, which controls stable supply of power to sub-modules in MMC connected to an HVDC system and a STATCOM. The power control apparatus includes at least one first resistor connected between P and N buses of MMC; a second resistor connected in series with the first resistor; a switch connected in series with the second resistor; a third resistor connected in parallel with the second resistor and the switch which are connected in series; a Zener diode connected in parallel with the third resistor; and a DC/DC converter connected between both ends of the Zener diode and configured to convert voltage across both ends of the Zener diode into low voltage, and supply the low voltage to the sub-modules, wherein a magnitude of current flowing through the Zener diode is controlled depending on ON/OFF switching of the switch.

A power harvesting circuit, a rectifier circuit and a capacitor. The rectifier circuit includes a diode circuit and a diode voltage reduction circuit. The diode circuit passes a current when a received RF signal has a first polarity and to substantially blocks the current when the received RF signal has a second polarity. The diode voltage reduction circuit is operably coupled to reduce a voltage drop of the diode circuit. The capacitor is operably coupled to convert the rectified signal into a DC supply voltage.

A power harvesting circuit a p-channel circuit, an n-channel circuit, an AC capacitance circuit, and an output capacitance circuit. The p-channel circuit includes a first diode element and a first start-up current circuit operably coupled to increase start-up current of the first diode element. The n-channel circuit includes a second diode element and a second start-up current circuit operably coupled to increase start-up current of the second diode element. The AC coupling capacitance circuit is coupled to the p-channel circuit and the n-channel circuit. The output capacitance circuit is coupled to the p-channel circuit and the n-channel circuit.

A drive circuit includes a first driver to control on/off of an upper arm, a second driver to control on/off of a lower arm, a first switching device including a first terminal connected with a power supply for the first driver, a second terminal connected with a power supply for the second driver and a control terminal, a booster circuit to turn on the first switching device by boosting a control signal which is at a high level when the lower arm is in an on state, a second switching device to cause continuity between the control terminal and the booster circuit when the control signal is at the high level, and first switch unit to short-circuit the control terminal and the terminal for grounding when the control signal is at the low level.