An the LED driving circuit, for driving an the LED load, includes: a bridge rectifier for rectifying an AC input voltage into a DC voltage; a serial capacitor voltage divider coupled to the bridge rectifier, including a plurality of serial capacitors; a half-bridge switch, coupled to the serial capacitor voltage divider; and a controller coupled to the half-bridge switch, for determining whether the DC voltage is higher than a threshold value and for controlling the half-bridge switch in a full-voltage mode or a half-voltage mode. In the full-voltage mode, the plurality of serial capacitors of the serial capacitor voltage divider synchronously supply power to the LED load. In the half-voltage mode, the plurality of serial capacitors of the serial capacitor voltage divider alternatively supply power to the LED load.

Disclosed herein is a AC direct LED driving apparatus. The light emitting diode (LED) driving apparatus includes: a rectifier configured to receive and rectify an alternating current (AC) voltage; an LED configured to emit light based on a rectified voltage received from the rectifier; a capacitor connected to a first terminal of the LED, and configured to drive the LED while alternating between charging and discharging sections according to a preset cycle; a first current driver connected to a second terminal of the LED and configured to control a path of current flowing in the LED and the capacitor based on different input voltage levels; a second current driver configured to control charging and discharging of the capacitor; and a first diode connected onto a current path of the capacitor and the second current driver, and configured to form a discharging path for driving the LED based on a charged voltage of the capacitor.

A wireless power receiver circuit and method for use in a wireless power transfer system are provided for providing a constant current and voltage to an electrical load, such as a chemical cell device. A wireless power receiver circuit include a first comparator circuit and a second comparator circuit configured to receive output signals output from the DC load circuit, compare the received output signal with a preselected reference voltage signal, and output first and second sub-control signals, respectively. A logical gate may generate a control signal based on a comparison of the first sub-control signal and the second sub-control signal, and feed the control signal back to a resonator circuit to control a state of an electrically-controllable switch.

A power conversion circuit includes an inductive switching power converter and a capacitive switching power converter. The inductive switching power converter switches an inductor to converter a DC power to a first power. The capacitive switching power converter switches a conversion capacitor to convert the first power to a charging power for charging a battery. The inductive switching power converter and the capacitive switching power converter flexibly operate in and dynamically switch between a regulation mode, a bypass mode or a combination thereof according to a parameter of the DC power.

A power conversion device includes a converter circuit, an inverter circuit including a switching element, a first capacitor, a buffer circuit, and a current supply circuit. The converter circuit converts a first alternating current into a direct current, and outputs the direct current to a pair of wires. The inverter circuit converts the direct current into a second alternating current by a switching operation of the switching element, and supplies the second alternating current to drive coils of a motor so that a drive shaft is rotationally driven. The first capacitor and the buffer circuit are connected between the pair of wires. The buffer circuit includes a second capacitor and a regulator connected in series. The current supply circuit supplies a current to support coils using energy stored in the second capacitor so that a load of the drive shaft is supported in a non contact manner.

A circuit includes a capacitor-drop power supply including a series combination of a resistor and a first capacitor. The capacitor-drop power supply includes an output and is adapted to be coupled to a light source. The circuit also includes a second capacitor, a switch, and an active clamp circuit. The second capacitor couples to the output of the capacitor-drop power supply. The switch couples in parallel with the series combination of the resistor and the first capacitor. The switch is configured to cause the light source to illuminate. The active clamp circuit couples to the capacitor-drop power supply. The active clamp circuit has an output coupled to the capacitor-drop power supply. The active clamp circuit is configured to cause current to continuously flow through at least one of the switch or the series combination of resistor and first capacitor regardless of a magnitude of the voltage across the second capacitor.

A convenient electronic circuit in which a switch is able to be switched through electric power obtained using weak radio waves is provided. An electronic circuit includes: a switch configured to switch a connection state between a power supply configured to output DC electric power and a load; a first antenna capable of receiving radio waves; a second antenna capable of receiving radio waves; a first power conversion circuit configured to convert electric power received by the first antenna into DC electric power and output the converted DC electric power from a first DC power output terminal; a second power conversion circuit configured to convert electric power received by the second antenna into DC electric power and output the converted DC electric power from a second DC power output terminal; and a control circuit configured to switch a connection state of the switch when a difference between electric power input from a first input terminal and electric power input from a second input terminal is larger than a predetermined value.

A power interrupter device includes a solid-state bidirectional switch and control circuitry to control the solid-state bidirectional switch. The bidirectional switch is connected between input and output terminals of the power interrupter device. The control circuitry includes driver circuitry and fault detection circuitry. The driver circuitry generates a regulated direct current (DC) voltage using current drawn from an input power source applied to the input terminal and applies the regulated DC voltage to a control input of the bidirectional switch. The fault detection circuitry is configured to sense a level of load current flowing in an electrical path between the input and output terminals, to detect an occurrence of a fault condition based on the sensed load current level, and to short the control input of the bidirectional switch to place the bidirectional switch in a switched-off state, in response to detecting the occurrence of a fault condition.

An apparatus including direct-current (DC)-alternating-current (AC) inverter circuitry, first and second circuits, and output circuitry. The DC-AC inverter circuitry inverts a DC input signal corresponding to an input voltage to an AC signal. The first circuit and second circuits respectively include inductive isolation circuits driven in response to power from the at least one AC signal, and rectifier circuits that responds to the inductive isolation circuits by outputting first and second rectified signals, where at least one of the first and second rectifier circuits characterized as being limited by a voltage breakdown rating. The output circuitry provides a DC output voltage signal and to cascade a plurality of signals, including the first and second rectified signals, to provide a voltage source that is dependent on the first and second rectified signals and greater than voltage breakdown rating.

A frequency converter includes a rectifier on an input side and a support capacitor downstream of the rectifier. Input-side phases of the rectifier feed the backup capacitor via multiple half-bridges of the rectifier. The half-bridges have active switching elements and the rectifier is designed as a recovery rectifier, The input-side phases are connected to grid-side phases of a multiphase supply grid via an upstream circuit. Each grid-side phase is connected to one of the input-side phases within the upstream circuit via a respective phase capacitor. A control facility controls the active switching elements when a first charge state of the support capacitor is reached and input-side phase voltages are applied to the input-side phases via the active switching elements. Voltages running in the opposite direction to the grid-side phase voltages are applied to the grid-side phases to which the input-side phases are connected via the phase capacitors.