An audio driver circuit includes a modulator circuit configured to receive an audio input signal and produce a first modulated digital pulse signal. The first modulated digital pulse signal has a magnitude that switches between a supply power voltage and a supply ground voltage. The audio driver circuit also includes a switched driver circuit coupled to the modulator circuit to receive the first modulated digital pulse signal and configured to provide a second modulated digital pulse signal for driving an MOS (metal oxide semiconductor) output transistor. The second modulated digital pulse signal has a same timing pattern as the first modulated digital pulse signal and has a magnitude that tracks linearly with the magnitude of the audio input signal.

An audio driver circuit includes a modulator circuit configured to receive an audio input signal and produce a first modulated digital pulse signal. The first modulated digital pulse signal has a magnitude that switches between a supply power voltage and a supply ground voltage. The audio driver circuit also includes a switched driver circuit coupled to the modulator circuit to receive the first modulated digital pulse signal and configured to provide a second modulated digital pulse signal for driving an MOS (metal oxide semiconductor) output transistor. The second modulated digital pulse signal has a same timing pattern as the first modulated digital pulse signal and has a magnitude that tracks linearly with the magnitude of the audio input signal.

A power supply circuit configured to generate an output voltage from a predetermined AC voltage. The power supply circuit includes a rectifier circuit rectifying the predetermined AC voltage, an inductor receiving a rectified voltage from the rectifier circuit, a transistor controlling an inductor current flowing through the inductor, and an integrated circuit configured to drive the transistor based on the inductor current and the output voltage. The integrated circuit includes a comparison circuit configured to compare a current value of the inductor current and a predetermined current value, and a timer circuit configured to receive a comparison result indicating that the current value is smaller than the predetermined current value, and output a signal indicating that the AC voltage is interrupted, when the current value has been smaller than the predetermined current value for a predetermined time period.

A load controller includes a control device, a switching device, an arc suppression circuit, and a control section. The control device is provided on an electric power supply path between first and second terminals coupled to an alternating-current electric power source, and controls electric power supply to a load provided on the electric power supply path. The switching device is provided on the electric power supply path and is to be in an open state or a closed state. The arc suppression circuit is to suppress discharge at the switching device. The arc suppression circuit is to be set to an enabled state or a limited state. The control section controls operation of the control device, the switching device, and the arc suppression circuit. The control section varies the arc suppression circuit from the limited state to the enabled state after bringing the switching device into the closed state.

A load control device for controlling power delivered from an alternating-current power source to an electrical load may comprise a controllably conductive device, a control circuit, and an overcurrent protection circuit that is configured to be disabled when the controllably conductive device is non-conductive. The control circuit may be configured to control the controllably conductive device to be non-conductive at the beginning of each half-cycle of the AC power source and to render the controllably conductive device conductive at a firing time during each half-cycle (e.g., using a forward phase-control dimming technique). The overcurrent protection circuit may be configured to render the controllably conductive device non-conductive in the event of an overcurrent condition in the controllably conductive device. The overcurrent protection circuit may be disabled when the controllably conductive device is non-conductive and enabled after the firing time when the controllably conductive device is rendered conductive during each half-cycle.

An air conditioning system includes a compressor including a motor, a condenser, and an evaporator; a drive including converter and an inverter, the converter and the inverter including power switching devices; a temperature sensor configured to sense a temperature in at least one of the converter and the inverter; a controller configured to communicate with the temperature sensor, the controller configured to provide a control signal to the inverter, the controller configured to execute: monitor the temperature; compare the temperature to a threshold; when the temperature exceeds the threshold, executing an operation to reduce a switching frequency of the power switching devices in the inverter.

A converter station, for a bipole power transmission scheme, includes a first voltage source converter and a second source converter. Each converters have a first terminal as transmission conduit and a second terminal as a return conduit. The second terminal of the return conduit of the first converter is electrically connected to the first terminal of the transmission conduit of the second converter as being a same terminal. Both voltage source converters also includes at least one converter limb which extends between the first and second terminals of each converters. The or each converter limb includes first and second limb portions that are separated by a corresponding first and second AC terminal which is for connection to a respective phase of a first or second AC network.

A converter station, for a bipole power transmission scheme, includes a first voltage source converter and a second source converter. Each converters have a first terminal as transmission conduit and a second terminal as a return conduit. The second terminal of the return conduit of the first converter is electrically connected to the first terminal of the transmission conduit of the second converter as being a same terminal. Both voltage source converters also includes at least one converter limb which extends between the first and second terminals of each converters. The or each converter limb includes first and second limb portions that are separated by a corresponding first and second AC terminal which is for connection to a respective phase of a first or second AC network.

A totem-pole single-phase PFC converter which controls low frequency-side node voltage to which an inductor is not connected into a linear shape within two poles of an AC power supply at a timing where a polarity of an input to the AC power supply is reversed.

An alternating current to direct current conversion circuit includes N first power converters instead of a boost circuit including a power switch with a high withstand voltage. The N first power converters each have an input end and theses input ends are connected in series, to perform power factor correction. Therefore, the alternating current to direct current conversion circuit includes no power switch with a high withstand voltage, so that the alternating current to direct current conversion circuit has a small volume, low switching loss, less energy loss, and good heat dissipation, thereby increasing power density.