67results about How to "Adjust duty cycle" patented technology

The invention discloses an optical clock extractor, which belongs to the technical field of optical communication and solves the problems that in the prior art, the optical clock extractor is complex and the extractable clock range thereof is limited. The optical clock extractor comprises a one-dimensional magnetic photonic crystal optical fiber coupler module and an adjustable off-set magnetic field unit for providing an applied magnetic field for the one-dimensional magnetic photonic crystal optical fiber coupler module, wherein the one-dimensional magnetic photonic crystal optical fiber coupler module comprises a collimating lens, a polarizer, a one-dimensional magnetic photonic crystal and a self-focusing lens. The invention also provides a method for performing optical clock extraction by using the extractor, which can achieve the adjustment of the spacing between transmission harmonic peaks to finally realize the optical clock extraction and process optical clock signals into the required forms. The optical clock extractor and the method not only achieve the optical clock extraction, but also can inhibit the jitter of the optical clock signals in the transmission process, and have the characteristics of simple realization, low cost, convenient operation, and automatic recognition of optical signal clocks.

The invention discloses a high-power dimming electrodeless lamp. The high-power dimming electrodeless lamp comprises an anti-electromagnetic interference filter, a bridge rectifier module, an active power factor corrector, a half-bridge inverter oscillatory circuit, a power output device, a starting controller, a high-frequency coupler, a dimming circuit and an HB0809 integrated circuit, wherein the half-bridge inverter oscillatory circuit is used for converting a direct current voltage into a high-frequency alternating voltage; the power output device is used for supplying output power to the half-bridge inverter oscillatory circuit when the half-bridge inverter oscillatory circuit works; the starting controller is used for controlling the turning on and turning off of the electrodeless lamp; the high-frequency coupler is used for coupling electric energy of the active power factor corrector and the power output device to the lamp tube of the electrodeless lamp; the dimming circuit is connected with an externally connected dimming control circuit; when the externally connected dimming control circuit supplies a 0 to 10-volt direct current (VDC) dimming control voltage signal to the dimming circuit, the dimming circuit works and then converts the alternating voltage into a 18-volt direct voltage; and the HB0809 integrated circuit is connected to the half-bridge inverter oscillatory circuit and used for controlling the alternately turning on and turning off of a first metal oxide semiconductor (MOS) tube and a second MOS tube in the half-bridge inverter oscillatory circuit to set working frequency, ignition time and ignition frequency. By a dimming electrodeless lamp circuit, a dimming function of the high-power electrodeless lamp can be realized.

The invention relates to a voltage stability control circuit of a wireless power supply system. The voltage stability control circuit is electrically connected with the output end of a wireless receiving end and comprises a filter circuit, a BUCK voltage reduction circuit and a BOOST voltage boosting circuit, the BUCK voltage reduction circuit and the BOOST voltage boosting circuit are connected in a series mode, and voltage stability control is conducted on the input voltage VIN by controlling the BUCK voltage reduction circuit to work in the through mode and controlling the BOOST voltage boosting circuit to work in the voltage boosting mode; or voltage stability control is conducted on the input voltage VIN by controlling the BUCK voltage reduction circuit to work in the voltage reduction mode and controlling the BOOST voltage boosting circuit to work in the through mode, meanwhile, a power supply circuit self-starting circuit is arranged, at the moment of powering up, the self-starting circuit is started and supplies power to a drive circuit, after the voltage value of an output end CY2 gets stabilized, the output end CY2 supplies power to the drive circuit, it is guaranteed that a stable power source is provided for the drive circuit, and stability of system operation is guaranteed.

The invention provides a fade-in or fade-out LED lamp programmable controller, which comprises an AC-DC conversion part, a PWM control part, a fade-in or fade-out LED lamp programmable control unit, a digital display part and a power output part. The fade-in or fade-out LED lamp programmable controller has the beneficial effects that through the fade-in or fade-out LED lamp programmable controller, an LED lamp gradually brightens from dark when turned on, and gradually darkens from light when turned off; human vision can gradually adapt to a light illumination change; the discomfort is reduced; and the comfort and the safety are improved. The fade-in or fade-out LED lamp programmable controller has the beneficial effects that after the fade-in or fade-out LED lamp programmable controller is used, the impact to a lamp tube caused by an initial current is reduced; and the service lifetime of the LED lamp tube is prolonged. The working principle of the fade-in or fade-out LED lamp programmable controller is that an AC is converted into a DC through the AC-DC conversion part 1, and the duty ratio of the power output part is adjusted through the PWM control part 2, so that the target of outputting a stable voltage is achieved.

The invention relates to an intelligent dimming device and method of an LED (light-emitting diode). The device comprises a power module, a reduction voltage circuit, a control module, a dimming drive module, a communication module, a light strength collecting module, a voltage collecting circuit and an LED lamp string; the power module is respectively in one-way connection with the reduction voltage circuit and the dimming drive module; the output end of the reduction voltage circuit is respectively connected with power inlet ends of the control module, the communication module and the light strength collecting module; the anode end of the LED lamp string is connected with the power module; the cathode end is connected with the dimming drive module, and the voltage collecting circuit is connected with the dimming drive module. The intelligent dimming device has the advantages that two dimming modes of automatic dimming and manual dimming can be achieved; the advantage of energy conservation of the LED is played to a greater extent; the dimming drive module utilizes a constant-current driver; the LED driver is in a work state all the time in a dimming process; the impact current born by the LED lamp string is small; improvement of the service life of the LED is facilitated, and the applicability is strong.

The invention provides an EPS power system based on dual processors. The EPS power system based on the dual processors comprises an input switch, an output switch, a charger, a storage battery pack, a storage battery pack monitoring module, an inverter, a bypass static switch, an inverting static switch and the DSP and further comprises a signal sampling and conditioning module and a monitoring module, wherein the monitoring module comprises the Loongson processor, a wireless communication module and a human-computer interaction module, the signal sampling and conditioning module is used for acquiring and processing measurement parameters and sending the parameters to the DSP, the storage battery pack monitoring module is used for monitoring the operating state of the storage battery pack and sending monitored parameters to the DSP, the DSP sends the measurement parameters and the monitored parameters to the Loongson processor, and the Loongson processor displays the measurement parameters and the monitored parameters through the human-computer interaction module and sends the measurement parameters and the monitored parameters to a remote terminal through the wireless communication module. Human-computer interaction and network monitoring of the EPS power system are established through the Loongson processor made in China, various kinds of information is acquired, displayed, stored and monitored when the system operates, it is guaranteed that all the parts of the system work orderly, and reliability of the system can be tested conveniently.

The invention provides a display device including a backlight module, a driving circuit of the backlight module, and a driving circuit of a light source; the backlight module has at least one backlight unit; the driving circuit of the backlight module contains a memorizer, an arithmetic unit and an output unit, wherein the arithmetic unit receives a display signal and make the black frame insertion operation to the display signal according to a default table of a panel to output an inserted black signal; the output unit receives and selectively outputs an enabling signal or an unable signal according to the inserted black signal; the driving circuit of the light source outputs a brightens control signal to into the backlight unit according to the enabling signal and the unable signal. The invention directly control an LED to be enable or to be unable according to the brightness of the display signal of the display device, which can not only save cost of the display device, but can adjust the working period of the display device as well.

The present invention discloses a high-speed pulse output duty ratio automatic regulation method based on a CPLD (Complex Programmable Logic Device). The method concretely comprises the following steps of: S1: depositing a high-speed pulse output duty ratio emitted by a high-speed pulse output EBRSRAM block in the CPLD into a plurality of frequency and duty ratio registers so understand the emitted high-speed pulse output duty ratio; and S2: allowing the high-speed pulse output EBRSRAM block to emit high-speed pulse and act to an MOS tube output module, wherein the output high-speed pulse frequency duty ratio is output according to a preset value to directly control the output of the MOS tube output module. The high-speed pulse output duty ratio automatic regulation methods output frequency values and duty ratio values read in the high-speed pulse output EBRSRAM block registers through a frequency and duty ratio state machine and compares the frequency values and duty ratio values readin the high-speed pulse output EBRSRAM block registers through the frequency and duty ratio state machine with frequency values and duty ratio values of the registers in the high-speed pulse output feedback EBRSRAM block so as to achieve automatic regulation of the high-speed pulse duty ratio of the PLC (Programmable Logic Controller) controller, reduce the deviation of the output high-speed pulse duty ratio and a preset value and ensure the high-speed pulse output of the PLC.

An annular oscillation circuit comprises a current mirror image circuit unit, an oscillation circuit unit, a switch shaping circuit unit and an inverter, wherein the current mirror image circuit unit is coupled to the oscillation circuit unit and provides image current to the oscillation circuit unit and the switch shaping circuit unit, and the oscillation circuit unit, of which the input end is coupled with the current mirror image circuit unit, comprises N annular oscillation subunits connected end to end, wherein N is an odd number and no smaller than three. The load capacitor of at least one oscillation subunit is an adjustable capacitance module. The switch shaping circuit unit is coupled to the output terminal of the oscillation circuit unit and switches on / off according to the output voltage of the oscillation circuit unit to shape the output voltage waveform of the oscillation circuit unit. The inverter is coupled to the output terminal of the switch shaping circuit unit. The annular oscillation circuit can output clock signals with high duty ratio.

The invention belongs to the field of LED lamps and discloses an LED lamp with a dimming function. An output end of a PWM signal generation circuit is connected to a G end of a field effect transistorQ1, a D end of the field effect transistor Q1 is connected to a power supply Vcc, an S end of the field effect transistor Q1 is reversely connected with a voltage stabilizing diode D1, and another end of the voltage stabilizing diode D1 is grounded. The voltage stabilizing diode D1 is also connected in series with an inductor L and a capacitor C1. An output end of the inductor L is connected withan LED light-emitting element which is formed by connecting a plurality of light-emitting diodes in series, another end of the light-emitting element is connected to a D end of a field effect transistor Q2, a G end of the field effect transistor Q2 is connected to an input pin of a single-chip microcomputer, an S end of the field effect transistor Q2 is connected to the ground through a resistorR1, and the single-chip microcomputer is connected with the Bluetooth module. According to the LED lamp, a Buck conversion topology circuit constant-current driving mode is adopted by a driving powersupply circuit, the circuit structure is simple, the voltage stabilization effect is efficient, the parallel connection of a plurality of groups of light-emitting elements can be realized, the expansion is carried out according to needs, and the application range is wide.

The invention relates to an LED pulsed light hair removal instrument. The LED pulsed light hair removal instrument comprises an LED light source module, a sensor module, an interaction module and a pulse control module, wherein the LED light source module is used for generating pulsed light, and light parameters of the pulsed light are obtained through calculation based on thermal relaxation of multiple cells of hair follicles and peripheral tissues of the hair follicles; the sensor module is used for acquiring working data; the interaction module is used for receiving a control command; and the pulse control module is used for controlling the LED light source module to work according to the working data and the control command. The hair removal instrument is small in size, stable in workand good in treatment effect.

The invention discloses a high-voltage linear constant current PWM (Pulse Width Modulation) photoelectric isolation receiving end, comprising a dimming control module, a filter rectifier module and a high-voltage linear constant current module, wherein the dimming control module is connected with the high-voltage linear constant current module via a dimming signal end, one end of the filter rectifier module is connected with the alternating-current mains supply, the other end of the filter rectifier module is connected with the high-voltage linear constant current module, and the high-voltage linear constant current module is connected with at least one group of LEDs (Light Emitting Diodes) connected in parallel and a circuit thereof. According to the high-voltage linear constant current PWM photoelectric isolation receiving end, two ends of the dimming control module isolated by a photo-coupler U1 avoid direct electrical connection, so that interference caused by electrical connection between an internal high-voltage control circuit and an external low-voltage circuit is effectively prevented, and static electricity can also be prevented. In addition, the duty cycle of the output end can be changed by adjusting the input end, and the magnitude of the output current can be adjusted, so that the purpose of adjusting the power of the load LEDs is fulfilled.

The invention discloses an inductive non-metallic ultrasonic emitting system, belongs to the technical field of non-metallic ultrasonic energy converter driving systems, and aims at providing an ultrasonic probe driving circuit without high-voltage power supply. The parameters of the ultrasonic probe driving circuit are convenient to adjust. The emitting system includes an ultrasonic emitting circuit and a square wave generator adjustable in duty ratio, the square wave generator adjustable in duty ratio includes an integrated chip, a first resistor, a second resistor, a sliding resistor, a first capacitor, a second capacitor, a first diode as a switch element and a second diode. The emitting system does not need to be provided with a direct-current high-voltage power supply, the safety hazard is eliminated, the size of the emitting circuit and the design cost are reduced, and the development cycle is shortened.

The invention discloses a stereoscopic vision measurement method, system and equipment for a large-size moving object and a storage medium, and belongs to the field of optical measurement. The method comprises: calibration is performed to obtain internal parameters, external parameters and distortion factors of the camera; synchronous light debugging is carried out to realize time reference unification of the measurement subsystem; the calibration unification of the space reference of the measurement subsystem is realized, and a reference coordinate system and a conversion relation from the measurement subsystem to the reference coordinate system are determined; synchronous triggering of the measurement subsystems is realized; a pair of images obtained by the left camera and the right camera at the same moment are processed to obtain a plurality of pairs of corresponding images with only coding targets; and the measurement of the three-dimensional coordinates of the corresponding target points in the corresponding measurement subsystems is completed, the three-dimensional coordinates are converted into the reference coordinate system and transmitted to the reference coordinate system, and the stereoscopic vision measurement of the large-size moving object is completed. The problems that an existing binocular stereoscopic vision measurement system is limited by the size of a camera view field, the measurement speed is low, and only static images can be measured are solved.

The invention relates to a pulse semiconductor laser lighting system as well as a lighting device used in a low-brightness area. The pulse semiconductor laser lighting system comprises a laser drivingcircuit, a pulse semiconductor laser and a laser spot homogenizer; the output end of the laser driving circuit is connected with the pulse semiconductor laser; the laser spot homogenizer is arrangedin front of light beams emitted by the pulse semiconductor laser; and the light beams emitted by the pulse semiconductor layer penetrate through the laser spot homogenizer. According to the laser lighting system, the system efficiency is improved, the system power consumption is reduced and high-power laser lighting application becomes possible.

The invention discloses a clock generator based on a phase-locked loop, which comprises a crystal oscillator, a phase-locked loop circuit, a clock adjusting module and a doubling circuit output module, wherein the clock adjusting module is used for receiving a first multi-path clock signal output by the phase-locked loop circuit, respectively adjusts the frequency and the phase of each first multi-path clock signal according to the preset frequency and phase of a target clock signal, and outputs multiple second multi-path clock signals respectively corresponding to all of the first multi-pathclock signals; the doubling circuit output module is used for receiving and merging the second multi-path clock signals output by the clock adjusting module, and outputs the target clock signal with the preset frequency and phase. The invention also discloses a corresponding clock generating method. The clock generator based on a phase-locked loop and the clock generating method can conveniently and flexibly adjust the frequency and the phase of the output target clock signal, and greatly broaden the band width which can be realized.

The invention relates to a singe-end-to-dual-end duty-ratio-adjustable circuit which comprises a first differential pair transistor M1, a second differential pair transistor M2 and a reverse proportion transistor M3. A grid electrode of the first differential pair transistor M1 is connected with an input signal, a drain electrode of the first differential pair transistor M1 is connected with a grid electrode of the second differential pair transistor M2 through a blocking capacitor C1, a drain electrode of the second differential pair transistor M2 and the drain electrode of the first differential pair transistor M1 are adopted as differential output ends, and a source electrode of the first differential pair transistor M1 and a source electrode of the second differential pair transistor M2 are both connected with a current source. A grid electrode of the inverse proportion transistor M3 is connected with a supply voltage, a drain electrode of the inverse proportion transistor M3 is connected with the grid electrode of the second differential pair transistor M2, and a source electrode of the inverse proportion transistor M3 is connected with the middle point of a bleeder circuit formed by the an R1 and an R2. Through the singe-end-to-dual-end duty-ratio-adjustable circuit, differential output and duty ratio adjustment can be achieved at the same time, and the structure is simple. The value of the R1 and the value of the R2 are set, and the duty ratio of an output waveform can be adjusted to 50 percent.

The invention discloses a high-voltage wide-range input method of a push-pull isolation type power source on the basis of SG2525. With respect to the characteristic that a photovoltaic component is high in direct-current output voltage generally ranging from 200VDC to 1000VDC and ultrawide in input range, the high-voltage wide-range input method includes steps of converting high voltage of 200VDC to 1000VDC into low voltage of 5V to -5V, and customizing a DC / DC (direct current) power source. The high-voltage wide-range input method further comprises a push-pull isolation type power source, 15V voltage output, + / -15V voltage output, magnetic core selection and selection of transformer turns. The high-voltage wide-range input method is high in input voltage, wide in range and low in cost, by the aid of over-voltage and over-current protection and mutual isolation of output of transformers, interference resistance is high, load is stable and maintenance is facilitated.

The invention provides a Lamb wave resonator with a POI structure and a manufacturing method of the Lamb wave resonator. The resonator includes at least one reflective layer including a high acousticvelocity substrate and a low acoustic velocity dielectric layer on the substrate, a piezoelectric layer bonded together with the dielectric layer on a side opposite the substrate, and an electrode onthe piezoelectric layer. The manufacturing method comprises the steps of providing a piezoelectric layer, and forming an IDT electrode on the piezoelectric layer; providing a substrate, and depositinga dielectric layer on the substrate; and performing low-temperature bonding on the dielectric layer and the piezoelectric layer. According to the invention, a Lamb wave S0 mode is excited, a high-frequency, high-bandwidth and low-insertion-loss Lamb wave resonator is realized, and the design requirements of high frequency, high electromechanical coupling coefficient, high Q value, low TCF value,no stray and the like are met at the same time.

The invention provides an LED driving power supply and a control method thereof, a lamp and a computer readable storage medium. The control method comprises the steps of acquiring and storing settingparameters, wherein the setting parameters comprise a preset current value and a preset voltage value, outputting a first control instruction according to the set parameters, and obtaining an actual current value and an actual voltage value, comparing the actual current value with a preset current value, comparing the actual voltage value with a preset voltage value, and outputting a second control instruction according to a comparison result if the actual current value is inconsistent with the preset current value and / or the actual voltage value is inconsistent with the preset voltage value until the actual current value is consistent with the preset current value and the actual voltage value is consistent with the preset voltage value. The invention further provides an LED driving powersupply, a lamp and a computer readable storage medium which apply the control method. According to the control method of the LED driving power supply, current parameters and voltage parameters meetingthe use requirements of the LED load can be provided for the LED load.

An electronic cut-in unit for operating a fluorescent lamp comprises a half-bridge inverter (Q1,Q2), a voltage divider (R1,R2) in parallel to the inverter input with the lamp (L) between the inverter output and the divider. The touch ratio of the inverter can be altered so that a direct current can be passed to the lamp at a desired level. An independent claim is also included for an operating process for the above unit.

The invention relates to a constant-current control method for an LED driving input-output low-voltage difference, including an LED lamp, a switching power supply driving control chip U1, an MOS turn-on time limiting module, and a current detection comparator, wherein the switching power supply driving control chip U1 detects a current by a CS, the MOS turn-on time limiting module is provided witha TON limiting circuit, the current detection comparator controls the turning off of an MOS Q1 by detecting the current in real time and by the output stage of an error amplifier EA, the switching power supply can fix the turn-on time of the MOS Q1 when the input and output voltages are close to each other, the error amplifier EA can also adjust the turn-off time of the MOS or adjust the duty cycle of MOS Q1 to achieve a constant current. The constant-current control method effectively solves an increase in current flowing through a lamp bead or the flicking of the lamp bead when an output lamp voltage drop and an input voltage drop are close to each other.

The invention provides an anti-oscillation voltage regulating circuit and a wireless charging system. The anti-oscillation voltage regulating circuit comprises a processing chip, wherein the processing chip is used for sampling input current and input voltage of a rectifying circuit and outputting a corresponding PWM signal so as to adjust the duty ratio of output voltage; or the processing chip is used for acquiring sampling current between a second end of a first capacitor and a second output end of the rectifying circuit and outputting the corresponding PWM signal so as to adjust the duty ratio of the output voltage when a switch tube corresponding to a first control end and a second control end of the processing chip is switched off; or the processing chip is used for sampling the input current of the rectifying circuit and outputting the corresponding PWM signal so as to adjust the duty ratio of the output voltage when the switch tube corresponding to the first control end and thesecond control end of the processing chip is switched off. According to the anti-oscillation voltage regulating circuit, the generation of the current oscillation phenomenon in the voltage regulationprocess is avoided by the above mode.

The invention provides a precise temperature control circuit of an anti-irradiation infrared detector refrigeration motor. The precise temperature control circuit comprises a temperature control sampling circuit, a temperature control circuit and a PWM generation circuit. The temperature control sampling circuit comprises a negative feedback constant current source circuit loaded to two ends of a temperature measuring diode in an infrared detector; two ends of the temperature measuring diode outputs voltage signals; the temperature control circuit comprises a difference amplification circuit, a reference voltage setting circuit, an isolation circuit and an error amplification circuit; input ends of the difference amplification circuit are connected to two ends of the temperature measuring diode, and the difference amplification circuit is used for extracting differential mode signals, changing with the temperature, of the temperature measuring diode; the reference voltage setting circuit comprises four voltage division resistors serially connected to a power supply; an input end of the error amplification circuit is connected with an output end of the difference amplification circuit, and the other output end is connected with a reference voltage through the isolation circuit, and the output end of the error amplification circuit outputs a comparison amplification level; and the PWM generation circuit comprises a comparison circuit and a triangular wave generation circuit.

The invention relates to an ECT-based dual-array sensor system with an adjustable duty ratio. The system comprises a shielding cover, a plurality of differential electrodes, a plurality of measuring electrodes and an adjustable bracket; the plurality of the measuring electrodes are mounted on the outer side of the outer circumferential surface of a pipeline through adjustable supports in an annular shape at intervals; the plurality of the differential electrodes are mounted on the outer sides of the plurality of the measuring electrodes through adjustable supports; each differential electrodecorresponds to one measuring electrode in position, and the measuring electrodes and the differential electrodes are concentrically arranged; the differential electrodes and the measuring electrodes are sequentially connected with external data acquisition system and imaging system through wires; and the shielding cover is arranged on the outer sides of the differential electrodes. By adding the differential electrodes, the precision can be greatly improved when an effective capacitance value is measured, and can be intuitively reflected from an imaging effect. The application of the ECT system is very wide, so that in a few industrial applications, the differential electrodes are easier to mount than isolated electrodes, the effect of denoising is achieved, and the effect is better than that of the isolated electrodes.

A display device and a drive method thereof are disclosed. The display device includes a display, a driver, a memory, and a controller. The display includes a display panel and a backlight unit with aplurality of light-emitting elements to display an image. The driver is electrically connected to the display to transmit a backlight control signal to the backlight unit. The memory stores a plurality of adjustment instructions, and each adjustment instruction includes a drive frequency and a control parameter. The controller is electrically connected to the display, the driver, and the memory.The controller is configured to determine a drive frequency and a control parameter corresponding to the drive frequency in the memory according to a frequency adjustment signal, and then adjust the backlight control signal according to the control parameter, to change a duty cycle of the backlight control signal, so that a refresh rate of the backlight unit meets a requirement of a user.

The invention provides an intelligent dimming device, which comprises: a voice recognition module for recognizing voice dimming instruction; a light sensor for illumination intensity in an environment; a dimming circuit for adjusting current output to at least one LED lamp so as to adjust the brightness of the at least one LED lamp; and an automatic control module for adjusting the duty ratio of aswitching tube in the dimming circuit according to a voice dimming instruction and / or according to the illumination intensity so as to enable the dimming circuit to adjust the current output to the at least one LED lamp. According to the intelligent dimming device, the duty ratio of the dimming circuit can be controlled and adjusted through voice, so that the working mode of the LED lamp is changed, and different light effects are displayed.

The invention discloses a wide-range excitation power generation and automatic double-charging switched reluctance generator converter system, which is composed of two storage batteries, ten switch tubes, nine diodes, five capacitors, a three-phase winding and two transformers. The two storage batteries and three switch tubes form an excitation power supply with excitation output voltage adjustable in a high-medium-low wide range, and the adaptability and the power generation capacity of the system are greatly improved. By directly depending on a simple converter loop of each phase winding andunder the aid of the excitation power supply, the problem about adjustment of the output power generation voltage in a large range is solved, and a subsequent boosting link is omitted during high-voltage output. Automatic isolated charging of the two non-common-ground storage batteries in the excitation power supply is realized only by adopting one switch tube, the sustainability and reliabilityof the system are improved, and the structure and control are simplified. The system is suitable for being applied to switched reluctance generator systems of various power inputs and various output loads.

The invention is suitable for the technical field of power electronics, and provides a harmonic compensation method and device for a PFC circuit and a terminal device, and the method comprises the steps: obtaining the current load rate of a target PFC circuit; determining a target compensation signal corresponding to the target PFC circuit under the current load rate based on the corresponding relationship between the load rate and the compensation signal, the target compensation signal being used for compensating the current harmonic of the main control signal under the current load rate; superposing the target compensation signal and a main control signal of a target PFC circuit to obtain a target control signal; generating a PWM control signal according to the target control signal; andcontrolling the target PFC circuit according to the PWM control signal. The original master control signal is compensated through the target compensation signal, so that the duty ratio of the PWM control signal is adjusted, the harmonic input of the circuit is reduced, the calculated amount is small and simple, the chip resource overhead is reduced, and the control stability is ensured.

The invention relates to a flyback switching power supply and a control circuit thereof. The control circuit comprises a pulse modulation controller which is used for outputting the PWM to drive a switch tube to be switched on and off. The comparison port of the pulse modulation controller is connected with the output end of an adjustment control module. The adjustment control module comprises a controllable precise voltage-stabilization source. The sampling end of the controllable precise voltage-stabilization source is used for being connected with an output voltage signal. The control circuit further comprises an overload protection module. The overload protection module comprises a first comparator. The non-inverting input end of the first comparator is used for being connected with anoutput current signal, and the inverting input end of the first comparator is connected with a first reference value. The output end of the first comparator is connected with the sampling end of thecontrollable precise voltage-stabilization source. According to the invention, the output voltage is controlled according to the change of the output voltage and the change of the overload current signal, so that the reliability is high. The dynamic response speed is increased, so that the switching frequency is accurately controlled. The duty ratio is adjusted.