131 results about "Filter capacitor" patented technology

The utility model relates to a MOS tube circuit, especially a kind of wide voltage input protection circuit for the voltage lifting of MOS tube, comprising: power input end, for receiving input voltage in wide voltage range;Filtering capacitor C1 is connected with the power input end;Floating ground circuit, including voltage stabilizing diode D1 and voltage dividing resistor R1, the cathode of voltage stabilizing diode D1 is connected with the power input end, the anode of voltage stabilizing diode D1 is connected with filtering capacitor C1 and voltage dividing resistor R1, the anode of voltage stabilizing diode D1 is as floating ground GND_D, voltage dividing resistor R1 is connected with base circuit GND, to make the anode of voltage stabilizing diode as the reference ground of PMOS tube gate control signal.The utility model provides a kind of wide voltage input protection circuit for the voltage lifting of MOS tube through floating ground circuit, significantly improves MOS tube circuit power adaptability and operating reliability.

This application discloses an automatic calibration circuit and method for mismatch compensation current of a phase-locked loop (PLL) charge pump, relating to the field of integrated circuit technology. The calibration circuit includes: a frequency and phase detector, a charge pump, an XOR module, a filter capacitor, a digital-to-analog converter (DAC) module, and a digital logic state machine. The first output terminal of the frequency and phase detector is connected to the first input terminal of the charge pump and the first input terminal of the XOR module, respectively. The second output terminal of the frequency and phase detector is connected to the second input terminal of the charge pump and the second input terminal of the XOR module, respectively. The output terminal of the XOR module is connected to the first terminal of the filter capacitor and the input terminal of the DAC module, and the second terminal of the filter capacitor is grounded. The output terminal of the DAC module is connected to the input terminal of the digital logic state machine, and the output terminal of the digital logic state machine is connected to the third input terminal of the charge pump. The output terminal of the charge pump is used to connect to the input terminal of the low-pass filter in the PLL. This application can compensate for the mismatch current of the charge pump in real time.

The utility model discloses a bus safety window opening alarm, including main control circuit, detection module, alarm module and power module, and main control circuit adopts special alarm chip ATW51H. Detection module is connected through JP1, JP2 interface, and is connected in parallel 16V / 0.1muF filter capacitor C2 to filter out the spurious echo, the drive circuit of alarm module is two stage series connection structure, is composed of triode Q3, triode Q2 and transformer T1, can enhance the driving capacity and protect the element, and power module contains triode Q1, switch S1 and LED pilot lamp D1, realizes the power supply management and control and state indication. Special alarm chip pin connection is reasonable, and the stability is promoted with the cooperation of auxiliary resistance. The alarm aims at improving the accuracy of safety window opening state detection, driving reliability and operating stability, realizes real -time monitoring and reliable alarm.

This invention provides a switching power supply, an AC-DC circuit, an input voltage detection circuit, and a method. The first end of the secondary coil of a transformer is connected to the anode of a rectifier diode, and the cathode of the rectifier diode is connected to the positive terminal of a filter capacitor. The second end of the secondary coil of the transformer, the negative terminal of the filter capacitor, and the positive terminal of the sampling capacitor are all grounded. The cathode of the diode is connected to the first end of the secondary coil of the transformer, and the anode is connected to the negative terminal of the sampling capacitor. The negative terminal of the sampling capacitor is grounded sequentially through a third sampling resistor and a second sampling resistor. The common terminal of the third and second sampling resistors is connected to a voltage detection terminal and, through a first sampling resistor, to a reference voltage input terminal. A reference voltage is input to the reference voltage input terminal. The control unit detects the voltage at the voltage detection terminal and calculates the magnitude of the input AC voltage based on the relationship between the AC voltage and the voltage at the voltage detection terminal.

This application relates to the field of air conditioning technology, and more particularly to an outdoor unit. The outdoor unit of this application has a cooling channel constructed within the motor housing of the compressor, and a mounting cavity is formed by providing a mounting shell on the motor housing. The inverter includes a first part and a second part. The first part is arranged within the mounting cavity, and heat dissipation is achieved using the cooling channel and the thermal conductivity of the motor housing. The second part is arranged independently of the motor housing. The first part includes an inverter module and a filter capacitor. The inverter module generates a significant amount of heat and is in contact with the motor housing, ensuring effective heat dissipation for the inverter module and improving its heat dissipation efficiency, thus preventing the temperature of the filter capacitor from being affected by insufficient heat dissipation from the inverter module. The filter capacitor generates less heat and is located on the side of the inverter module away from the motor housing. The remaining cooling capacity after heat exchange with the inverter module via the refrigerant channel is used to dissipate heat from the filter capacitor, ensuring its service life and reducing maintenance frequency.

The application discloses a low ripple charge pump circuit with adjustable output, wherein the negative plate of a first pump capacitor is connected to the output terminal of an operational amplifier and the ground through a third switch and a fourth switch respectively, and the positive plate is connected to the power supply and the output terminal through a first switch and a second switch respectively; the negative plate of a second pump capacitor is connected to the output terminal of the operational amplifier and the ground through a seventh switch and an eighth switch respectively, and the positive plate is connected to the power supply and the output terminal through a fifth switch and a sixth switch respectively; the positive plate of a filter capacitor is connected to the output terminal, and the negative plate is grounded; a first feedback resistor and a second feedback resistor are connected in series between the output terminal and the ground; the inverting input terminal of the operational amplifier is connected to the feedback voltage between the first feedback resistor and the second feedback resistor, and the non-inverting input terminal is connected to the reference voltage. The application has adjustable output voltage, and the output ripple is far smaller than that of a conventional charge pump.

This application belongs to the field of wireless charging technology, specifically relating to a constant current and constant voltage wireless charging system and method based on a three-coil loosely coupled transformer, including an inverter circuit, a primary-side compensation circuit, a resonant circuit, a secondary-side compensation circuit, a rectifier circuit, and a filter capacitor; the resonant circuit has an anti-parallel coil structure, with the third coil located on the secondary side and a single coil on the primary side; its advantages are high misalignment tolerance, load-independent output, and high efficiency.

The utility model provides a kind of sensor reference power supply of automobile air conditioner, automobile air conditioner and car, and this sensor reference power supply includes: the positive input pin of operational amplifier is connected with the one end of first resistance, and the other end of first resistance is connected with 5V power supply, the one end of first filter capacitor respectively;The negative input pin of operational amplifier is connected with the one end of second resistance, and the other end of second resistance is connected with the cathode of diode;The positive side power supply pin of operational amplifier is connected with 12V power supply, the one end of second filter capacitor respectively;The output pin of operational amplifier is connected with the one end of third resistance, and the other end of third resistance is connected with the anode of diode, the cathode of diode is connected with the other end of second resistance, the one end of inductance, the other end of inductance is connected with the one end of third filter capacitor.The utility model's scheme can effectively reduce material cost under the premise of not reducing reference power supply precision and reliability, increase market competitiveness for enterprise.

The application discloses a photovoltaic panel parallel fault detection circuit and method, which is electrically connected with N photovoltaic panels, and comprises N plug-in parts electrically connected with the N photovoltaic panels, wherein the plug-in parts comprise a first port and a second port, the first port is electrically connected with the photovoltaic panel, and N is an integer greater than or equal to 2; a first line connected with a first pin of the second port of the plug-in part and a second line connected with another pin of the second port of the plug-in part; the other end of the first line and the second line is electrically connected with a transformer; and an analog load and a filter capacitor are connected in parallel between the first line and the second line. The beneficial effects are as follows: by arranging independent detection circuits and control switches in the loop of each photovoltaic panel, the detection blind area caused by parallel voltage clamping is overcome, open circuit, reverse connection and leakage current faults of specific photovoltaic panels can be accurately identified and located, and the accuracy and timeliness of system fault diagnosis are improved.

This invention discloses a BUCK circuit with precisely adjustable current and its adjustment method. The circuit includes a time loop control circuit and a BUCK constant current circuit. The input terminal of the time loop control circuit is connected to the output terminal of the BUCK constant current circuit to obtain the output current Iout of the BUCK constant current circuit. The output terminal of the time loop control circuit is connected to the input terminal of the BUCK constant current circuit to adjust the output current Iout of the BUCK constant current circuit. The time loop control circuit includes a sampling circuit I0, a comparator I1, a control calculation module I2, and an AND gate I3. The BUCK constant current circuit includes a driver circuit I4, an NMOS transistor Q0, a freewheeling diode D0, an energy storage inductor L0, a current sensing resistor R0, a filter capacitor C0, a light-emitting diode D1, and a power supply. The adjustment method includes: obtaining the sampling voltage Vsns and calculating the output current Iout; if the output current Iout is adjusted to a high current adjustment, it enters the analog adjustment mode; otherwise, it enters the mixed analog-digital adjustment mode. The output current of the BUCK circuit can be precisely adjusted.

This invention relates to a circuit board for an ozone generator with frequency tracking functionality. The circuit board includes a frequency tracking circuit comprising an RC oscillation unit, an LC resonant unit, a current sampling unit, a comparison control unit, a voltage divider bias unit, and a frequency limiting protection unit. The LC resonant unit includes a resonant inductor T1 and a resonant capacitor C1, used to drive the ozone sensor. The current sampling unit includes a sampling resistor R8 connected in series in the LC resonant circuit, used to acquire the circuit current signal. The comparison control unit includes a comparator U1, a transistor Q1, a rectifier diode D2, and a filter capacitor C3. The voltage signal from the sampling resistor R8 is rectified by D2 and filtered by C3 before being input to the inverting input of U1. The voltage divider bias unit includes resistors R3 and R6. The RC oscillation unit is connected to the transistor Q1. This invention can adapt to capacitance changes during ozone sensor power-on and operation, automatically tracking the frequency and achieving resonance, while ensuring stable output power, extending device lifespan, and improving ozone generation efficiency and overall reliability.

This invention relates to power electronic conversion technology, aiming to provide a three-port single-stage bidirectional DC-AC converter with photovoltaic, energy storage, and charging capabilities, and its control method. It includes a public grid interface unit and two DC port power units connected to different DC sources. The former includes a grid-side full-bridge circuit, a power frequency polarity reversal circuit, and a filter circuit, with the output terminal on the public grid side led out from the power frequency polarity reversal circuit. The latter includes an input filter capacitor, a full-bridge circuit, and a high-frequency transformer. The input filter capacitor is connected in parallel across the DC source and the full-bridge circuit, and the output midpoint of the full-bridge circuit is connected to the primary winding of the high-frequency transformer. The secondary windings of the high-frequency transformers in the two DC port power units are connected in parallel, and their common connection point is connected to the midpoint of the bridge arm of the grid-side full-bridge circuit. This invention completely eliminates the intermediate high-voltage DC bus and large-capacity electrolytic capacitor, structurally improving power density and long-term reliability; it can flexibly support various complex operating modes.

The application discloses a three-phase series voltage balance control method of a novel AC / DC converter, which is applied to a modular multilevel converter, the converter comprising three single-phase power units in series connection, a transformer and a DC filter, each single-phase power unit being composed of a cascade module chain and a commutation bridge, the cascade module chain comprising a plurality of power sub-modules in series connection, and each sub-module containing a sub-module capacitor; the method comprises the following steps: detecting the average voltage of three-phase sub-modules in real time, triggering the voltage balance control when detecting the imbalance, controlling the output voltage of the cascade module chain to contain harmonic voltage, the frequency of the harmonic voltage being equal to the series resonance frequency of the DC valve side filter inductance and the DC filter capacitor, adjusting the phase of three-phase harmonic voltage, so that the harmonic voltage of the phase with lower voltage and the harmonic current act on the sub-modules to charge the sub-modules, and the harmonic voltage of the phase with higher voltage acts on the sub-modules to discharge the sub-modules, thereby realizing voltage balance, and the control is exited when the three-phase voltage is balanced and the three-phase harmonic voltage is all zero; and the application can realize the consistency of the average voltage of three-phase sub-module capacitors.

This utility model discloses a power supply circuit for a rail transit lighting system, wherein the anode of the anti-reverse diode D2 is connected to the DC power input terminal V. in The cathode is connected in series with fuse F1, then splits into two paths. The first path connects to the input pin VIN of the high-voltage linear regulator U1, and the second path is grounded through rectifier diode D1 and then connected in parallel with input filter capacitor C2. The input pin VIN of U1 is connected to the positive terminal of C2, the output pin OUT of U1 is grounded through the output filter capacitor C1, and the adjustment pin ADJ of U1 is grounded through resistor R6. The base of transistor Q2 is grounded through resistor R6, and the base is also connected to the output pin OUT of U1 through resistor R2. The collector is connected to the input pin VIN of U1, and the emitter of Q2 is directly connected to the power output terminal V. out Simultaneously, the adjustment pin ADJ of U1 is connected via resistor R4. Through the above method, the power supply circuit for the rail transit lighting system of this utility model adopts the TL783CKCSE3 high-voltage linear regulator, which supports wide voltage input and high voltage differential drop, effectively coping with fluctuations in the rail transit power grid and ensuring stable operation of the lighting system.

This application provides a method, system, device, and medium for designing output filter parameters for a frequency converter, relating to the field of frequency converter filtering technology. The method includes: obtaining target parameters of the frequency converter; determining a first resonant frequency constraint condition for the output filter in the frequency converter based on the rated fundamental frequency and pulse width modulation switching frequency; determining the total control delay based on the pulse width modulation switching frequency, and determining a second resonant frequency constraint condition for the output filter based on the total control delay and the controller parameters of the frequency converter, thereby determining the resonant frequency range of the output filter; determining the range of filter capacitor parameters for the output filter based on the rated voltage, rated current, and rated fundamental frequency; and determining the target resonant frequency, target filter capacitor parameters, and target filter inductance parameters for the output filter based on the resonant frequency range, the filter capacitor parameter range, and the motor stator inductance. This application can effectively suppress the resonance of the frequency converter output filter and effectively avoid the risk of instability.

This invention discloses a wireless charging system and method for achieving constant current and constant voltage output based on variable topology. The system includes a transmitting section and a receiving section; the transmitting section includes a DC power supply U. D The system consists of a composite high-frequency inverter H, resonant circuit 1, and resonant circuit 2; the receiving section includes resonant circuit 3, rectifier D, and filter capacitor C. F and battery load R B The method includes: after charging is initiated, both Q2 and Q4 are turned on, while Q1 and Q3 operate alternately with a 50% duty cycle, and the system uses a three-coil structure to charge the battery at a constant current. When the load voltage rises to a preset voltage, Q1 turns on, Q2 turns off, and Q3 and Q4 operate alternately with a 50% duty cycle, and the system uses a two-coil structure to charge the battery at a constant voltage. When the battery is fully charged, the system automatically cuts off the inverter's power output and stops charging. Compared to existing similar technologies, this invention requires no additional AC switch or frequency switching control; it has a simple structure, low cost, and convenient control.

The application discloses a direct current source device and a direct current adjusting method, relates to the field of direct current tests, and comprises an isolation transformer, a rectifier bridge, a filter capacitor, a digital potentiometer, a voltage gear switching switch, a first current-limiting resistor, a second current-limiting resistor, a collection module and a control module, the collection module is used for collecting current values and voltage values, the control module is connected with the collection module, the digital potentiometer and the voltage gear switching switch respectively, an input end of the isolation transformer is connected with an alternating current source, and an output end of the isolation transformer is connected with the rectifier bridge; the rectifier bridge is connected in parallel with the filter capacitor, and then connected in series with the digital potentiometer; an output end of the digital potentiometer is connected with a common end of the voltage gear switching switch; a first movable end of the voltage gear switching switch is connected with the first current-limiting resistor, and a second movable end of the voltage gear switching switch is connected with the second current-limiting resistor; the other end of the first current-limiting resistor and the other end of the second current-limiting resistor are both connected with a positive electrode as a second load. The application realizes automatic voltage switching, meets different requirements and improves compatibility.

The application discloses a current mode staggered control converter and a control chip, wherein the converter comprises a VIN input power supply with a voltage of 20V-100V, forward transformers T1 and T2, two output paths formed by the transformers and subsequent devices, a capacitor C0 as a VCC pin filter capacitor, a resistor R3 as an RT pin resistor connected to the ground and used for controlling the frequency of an oscillator, capacitors C1 and C2 as COMP1 and COMP2 pin capacitors connected to the ground and used for adjusting loop stability, capacitors C3 and C4 as SS1 and SS2 pin capacitors connected to the ground and used for realizing soft start of the system, N3 and N4 as natural synchronous rectifier devices in the forward converter, the first output channel and the second output channel adopting the same structure, an auxiliary winding La providing power supply for an IC control chip VCC through a diode D1, and an output capacitor Cout1 as an output capacitor of the first channel. The whole system is driven and controlled by only one control chip, and the power density is improved, the volume of the scheme is reduced, the cost of the scheme is lowered, and the system performance is not sacrificed.

The utility model relates to power supply circuit technical field discloses a kind of drive high P power supply circuit, including conversion chip U1, the constant-current output loop compensation end of conversion chip U1 is connected with chip reference ground terminal and the one end of sampling resistance respectively by first capacitor CS1, the other end of sampling resistance is connected with the current sampling input end of the conversion chip U1, the current sampling input end of conversion chip U1 is connected with the cathode of first freewheeling diode D1, the anode of first freewheeling diode D1 is connected with input power negative pole, the chip power supply end of conversion chip U1 is connected with chip reference ground terminal by charge filter capacitor CS2, the chip power supply end of conversion chip U1 is connected with the auxiliary circuit for power supply compensation, sampling resistance is connected with the anode of load by auxiliary circuit, the demagnetization detection end of conversion chip U1 is connected with the voltage dividing resistance for detecting the demagnetization time of the auxiliary circuit;The utility model effectively improves conversion efficiency, and effectively reduces improvement cost.

This invention relates to the technical field of integrated circuit manufacturing, specifically to a composite heat dissipation and filtering integrated device for power PCBs, comprising a heat dissipation platform one, multiple plungers, a thermally conductive microcapsule layer, a thermal pusher strip, a heat dissipation platform two, a metal thermally conductive block, and a linkage mechanism; the heat dissipation platform one is mounted on the upper surface of the power device, and the heat dissipation platform one has multiple mounting holes with bottom openings; by setting up an array of plungers and thermal pusher strips, the thermal expansion effect is used to achieve adaptive balance of the heat dissipation clamping force of the power device, eliminating local hot spots; the pressure-triggered microcapsule rupture mechanism releases thermally conductive grease as needed, dynamically compensating for contact thermal resistance; the metal thermally conductive block and linkage mechanism convert the plunger displacement into synchronous clamping force on the filter capacitor, effectively suppressing the failure of the filter capacitor due to microcracks caused by PCB bending or vibration, realizing coordinated adaptive adjustment of heat dissipation and filtering, and significantly improving the long-term reliability of the power PCB under harsh operating conditions.

The present invention provides an electrical discharge machining (EDM) pulse power supply and machining method based on a three-level Cuk circuit, comprising: a three-level Cuk main power circuit, a DC voltage source, an FPGA control circuit, and a drive circuit. The three-level Cuk main power circuit is used to connect the EDM gap to achieve discharge machining. The DC voltage source outputs an adjustable DC voltage to power the three-level Cuk main power circuit. The FPGA control circuit generates a PWM signal that enters the drive circuit. The drive circuit processes the PWM signal to generate a drive signal to control the on / off state of the switching transistors in the three-level Cuk main power circuit. This invention effectively increases the switching frequency of the system, significantly reduces voltage and current ripple, and lowers the selection requirements for switching transistors, filter inductors, and output filter capacitors. Simultaneously, it can meet the requirements of high and low voltage composite output for EDM pulse power supplies, efficiently and reliably fulfilling the requirements for EDM pulse power supplies.

This utility model discloses a power conversion circuit and system. The circuit includes an upper bridge arm, a lower bridge arm, and a bridge arm connecting piece. The input terminal of the upper bridge arm is connected to the positive terminal of the bus. The output terminal of the upper bridge arm is connected to the bridge arm connecting piece via an output piece. The bridge arm connecting piece is connected to the input terminal of the lower bridge arm via an input piece. The output terminal of the lower bridge arm is connected to the negative terminal of the bus. An energy storage filter capacitor is connected between the positive and negative terminals of the bus. The positive and negative terminals of the bus are arranged opposite to each other. This utility model reduces the loop area formed by the positive and negative terminals of the bus, effectively reducing external electromagnetic radiation, thereby improving stability and power density.

The application discloses a full N type GaN HEMT half-bridge driving circuit and relates to the field of GaN HEMT driving circuits.The full N type GaN HEMT half-bridge driving circuit comprises a biasing stage circuit and a driving stage circuit.The biasing stage circuit comprises a filter capacitor C1 and pull-up tubes M1, M3, M6, a resistor R3 and a resistor R5 connected with a power supply; and a bootstrap capacitor C2 and pull-down tubes M4 and M7 connected with the driving stage circuit.The driving stage circuit comprises a bootstrap diode D1 and a pull-up tube M9 connected with the power supply; a bootstrap capacitor C3 and a pull-up tube M9 and a pull-down tube M connected with an output end. 10 The application improves the output load capacity by using the bootstrap boosting method, and realizes the full N enhancement type GaN HEMT half-bridge driving circuit to drive the GaN HEMT device.

The utility model relates to a kind of optical fiber receiving circuit module for one turns many under magnetic field environment, including two-way optical fiber plug input to output end, filter capacitor C1, filter capacitor C2, pull-up resistor R1, pull-up resistor R2, signal reverser, multi-or non gate output circuit and TTL level output circuit;The utility model relates to the technical field of optical fiber receiving circuit, the optical fiber receiving circuit module for one turns many under magnetic field environment, realizes two-way optical fiber signal result logic truth table to determine output, is converted into serial communication, with scalability simultaneously, after accumulation can realize one-to-many optical fiber communication, ensure normal communication under magnetic field environment, reduce cost, without separate optical fiber converter, scalable one-to-many, realize the design of multiple optical fiber module conversion serial port, can be realized stable in high magnetic field environment, communication without influence, for receiving instruction reduces the circuit design of redundancy, maximum degree improves stability and reduces cost.

The utility model discloses a low -power feedback switching power supply relates to the field of electronic circuit. Including input module, control module, voltage transformation module, feedback module and output module. Input module contains lightning protection temperature control and filter rectifier circuit, realizes the lightning protection, filter and rectification to external power supply, control module integration starts, the feedback of original side, overcurrent monitoring and switching circuit, is the control core of power supply, voltage transformation module passes through transformer and peak current absorption circuit, realizes the safe transformation of voltage, feedback module utilizes the combination of photocoupler and voltage stabilizer, real -time acquisition output voltage and feedback to control module, output module adopts synchronous rectifier circuit, and cooperates filter capacitor and common mode inductance, realizes high -efficient rectification and filter. The utility model discloses through synchronous rectification technology reduction conduction loss, combines the adaptive feedback system fast adjustment duty cycle, and the power efficiency and output voltage stability are improved significantly, have high reliability, low loss, response speed fast and so on advantage.

The utility model relates to a protection structure based on a fuse and a filter capacitor. The protection structure comprises a base plate, the fuse, the filter capacitor, a PDU wire harness, a common mode inductor, a copper bar positive electrode, a copper bar negative electrode and a connecting sheet. One end of the PDU wire harness is respectively connected with the connecting sheet and the negative electrode of the copper bar, the other end of the PDU wire harness passes through the common mode inductor (4), and the positive electrode of the copper bar, the negative electrode of the copper bar and the connecting sheet are all arranged on the bottom plate. According to the utility model, the fuse and the filter capacitor are organically combined together, so that the fuse can effectively suppress electromagnetic interference and improve the overall performance of the motor controller while realizing circuit protection, a traditional fuse can only cut off a circuit when current is overloaded, while the product has accurate overcurrent protection capability and can effectively prevent electromagnetic interference when the current is overloaded. And the problem of electromagnetic interference can be effectively solved.

This application discloses a charging pile and its control method, relating to the field of DC charging technology. The charging pile includes a three-phase parallel resonant converter, a controller, and a relay control circuit. The three-phase parallel resonant converter is connected to both the controller and the relay control circuit. The three-phase parallel resonant converter includes three independent and structurally identical conversion units. Each conversion unit includes an input rectifier bridge, a resonant circuit, an isolation transformer, and a rectifier circuit connected in sequence. The resonant circuit includes a choke coil, a switching transistor, a shunt capacitor, a resonant capacitor, and a resonant coil. The rectifier circuit includes a rectifier capacitor, a diode, a filter capacitor, a first filter coil, and a second filter coil. The controller is used for: soft-start control of the output voltage and output current during the startup phase, and control of the series and parallel connection state of the relay control circuit; and for performing input-side and output-side regulation and drive wave generation control during the operation phase. This application has the advantages of high power density, small size, and simple control.

The utility model relates to flyback power supply technical field especially relates to an improve flyback power supply harmonic's circuit, including input rectifier subcircuit, transformer, output subcircuit, control subcircuit and feedback subcircuit, has increased diode D2, diode D3, capacitor C3, diode D1 and the diode D4 and inductance L2 with low loss characteristics on the basis of the bridge rectifier filter capacitor of traditional flyback power supply circuit, and then composed a harmonic suppression circuit, will input current THD drop to below 10%, and compared with traditional PFC scheme, efficiency only drops about 0.5%, the whole flyback power supply circuit does not need to use bulky capacitor or inductance, the volume of circuit whole reduces, effectively reduced the circuit manufacturing and assembly cost.