130results about How to "Reduce switching loss" patented technology

A power factor correction method and apparatus which use Pulse Frequency Modulation (PFM) to control an AC / DC converter is disclosed. The average current drawn by the AC / DC converter is compared with a reference sinusoidal signal and the error is used to determine the switching frequency. The switching frequency varies with the sinusoidal reference signal such that the converter emulates a resistive load. By using PFM control, EMI is spread over a range rather than concentrated at a few frequencies. Since the switching frequency decreases with the loading of the converter, the switching loss decreases with the loading as well. Thus, the need of meeting efficiency standards, e.g. the 80 PLUS and Energy Star, can be fulfill without extra circuitry.

The invention relates to a constant-current circuit with the characteristics of voltage compensation and zero potential switching. The constant-current circuit is a single-switch inverse magnetic converter, and comprises a control circuit, a detection resistor, a transformer, a partial voltage compensation circuit and a primary side power switch, wherein the control circuit acquires the primary side current information of the transformer by using the detection resistor, and can acquire a compensation signal from an input voltage by using the partial voltage compensation circuit, and control the threshold voltage of the primary side power switch according to the compensation signal, so that the peak voltage of the primary side current can be fixed at a reference voltage due to the compensating action of the compensation signal, and the output current of the constant-current circuit is kept in a constant state. The constant-current circuit provided by the invention has the advantages that under the conditions of not using a secondary constant-current detection circuit and a feedback circuit, all necessary information can be obtained at the primary side only by using cheap electronic components and very simplified circuit layouts, and a constant output current can be generated in a wide-area input voltage state.

Exemplary embodiments of the present invention disclose a unidirectional heterojunction transistor including a channel layer made of a first nitride-based semiconductor having a first energy bandgap, a barrier layer made of a second nitride-based semiconductor having a second energy bandgap different from the first energy bandgap, the barrier layer including a recess, a drain electrode disposed on a first region of the barrier layer, and a recessed-drain Schottky electrode disposed in the recess of the barrier layer, the recessed-drain Schottky electrode contacting the drain electrode.

The invention is suitable for the field of power supply, and provides a switch direct-current boosted circuit, a boosted device and an LED illuminating system. The switch direct-current boosted circuit comprises an inductor L1, an inductor L2, a diode D, a capacitor C, a resistor R1, a resistor R2, a MOS tube Q and a switch control unit. Due to the addition of the new inductor in the switch direct-current boosted circuit, the problems of large switch loss, small amplitude of voltage rise and the like in the prior art are solved, so that the switch direct-current boosted circuit improves the work efficiency and the amplitude of output voltage rise.

The invention discloses a production method of a groove-type power semiconductor with a low grid charge and a structure thereof. The production method is characterized by comprising the following steps of: providing a first conductive type semiconductor substrate and forming a first conductive epitaxial layer and a second conductive type body area on the first conductive type semiconductor substrate; and forming a plurality of grooves; forming a first insulating layer on the second conductive type body area and on the lateral surface of each groove; forming a polysilicon side wall on the sidewall of each groove and exposing one part of the bottom surface of the groove; filling a dielectric structure into each groove; filling polysilicon above the dielectric structure of each groove; forming a metallic silicide on the polysilicon, wherein the metallic silicide is a first phase composition; and converting the metallic silicide from the first phase composition into a second phase composition. The invention can improve the switching speed and achieve the effect of reducing the switching loss.

The invention relates to a device for reducing standby power consumption of a display device, the display device comprises a power supply system which is used for controlling power transmission through a power changeover switch of a power supply controller, and an image zooming device which is used for receiving power supply voltage from the power supply system, and the device is characterized in that the device comprises a power supply monitoring circuit and an optical coupler, wherein the power supply monitoring device is used for monitoring the power supply voltage under the control of a mode signal during the standby mode, and accordingly producing a control signal; the optical coupler is connected with the power supply monitoring circuit and used for converting the control signal to an enable signal, and sending the enable signal to the power supply controller so as to enable or close the power supply controller. The device and the method for reducing the standby power consumption of the display device have the advantages of reducing changeover loss, reducing the power consumption and maintaining that the power supply voltage is sufficient to lead the image zooming device to operate normally.

The invention relates to the technical field of chemical gas separation and liquefaction, and provides a helium ultralow-temperature purification and liquefaction system. The system comprises a purification unit, a liquefaction unit, a pre-cooling unit and a cold transfer unit, wherein the liquefaction unit communicates with the purification unit through a gas supplementing channel, and the cold transfer unit is connected between the purification unit and the liquefaction unit; the purification unit comprises a raw material helium inlet pipe, a first purification heat exchanger first flow channel, a low-temperature adsorber, a second purification heat exchanger first flow channel, an ultralow-temperature adsorber, a second purification heat exchanger second flow channel, a first purification heat exchanger second flow channel and a high-purity helium outlet pipe which are sequentially connected through pipelines; and a working temperature interval of the low-temperature adsorber is a liquid nitrogen temperature zone, and a working temperature interval of the ultralow-temperature adsorber is 25-40K. According to the invention, through two-stage adsorption of the low-temperature adsorber and the ultralow-temperature adsorber of the purification unit, different impurities in raw material helium are respectively purified in different temperature zones, so that the helium switching loss in a purification process is reduced, and the helium extraction rate is improved.

The invention discloses a control circuit used for controlling a switching type voltage stabilizer in a buck-boost converter. The switching type voltage stabilizer comprises a first switch, a second switch, a third switch and a fourth switch. The control circuit comprises an error detector, a triangular wave generator, a comparator, an oscillator and a control signal generator. The error detector is used for generating error signals corresponding to output voltage of the switching type voltage stabilizer. The triangular wave generator is used for generating triangular wave signals. The comparator is used for comparing the error signals with the triangular wave signals to generate comparison signals. The oscillator is used for generating oscillation signals. The control signal generator is used for controlling operation of the first switch, the second switch, the third switch and the fourth switch according to the comparison signals, the oscillation signals and time-impulse signals and used for enabling the switching type voltage stabilizer to be switched between a boosting mold and a voltage reduction mode and not to be operated in a buck-boost mode. The control circuit can prevent the switching type voltage stabilizer from entering the buck-boost mode, therefore, at most two switches of the switching type voltage stabilizer can be switched at the same time, and switching loss of the buck-boost converter can be effectively reduced.