Auxiliary power supply device based on flyback converter

Abstract

The utility model discloses an auxiliary power supply device based on a flyback converter, and relates to the technical field of auxiliary power supplies. The auxiliary power supply device provided by the utility model adopts a direct-current bus to supply power, and combines the design of the first starting circuit, the flyback chip, the peripheral circuit, the VCC circuit and the switching tube driving circuit, so that an alternating-current rectifying circuit, a power factor correction circuit and a repeated alternating-current power taking circuit are reduced, the circuit design is simplified, the circuit cost is reduced, the starting time is shortened, and the working efficiency is improved. And the technical index of starting in one second is reached.

Description

Technical Field

[0001] This utility model relates to the field of auxiliary power supply technology, specifically to an auxiliary power supply device based on a flyback converter. Background Technology

[0002] As a key facility for ensuring flight safety, airport navigation lighting systems require dimmers to be equipped with highly reliable auxiliary power supplies.

[0003] The auxiliary power supply of the dimmer in the existing navigation light system adopts the AC power supply mode, that is, the AC power is directly taken from the input of the dimmer. This power supply method has the following problems in practical applications: (1) Insufficient voltage adaptability: The dimmers commonly used in airports are generally divided into 220V models and 380V models. For the 380V model, since it adopts a three-phase four-wire system (A / B / C / N) power supply, if the auxiliary power supply adopts a single-phase power supply mode, it is easy to cause power interruption due to the loss of a certain phase. In order to ensure reliability, multiple power supply ports need to be set up, which significantly increases the system complexity and wiring cost; (2) Degraded power quality: In the AC power supply mode, the switching power supply circuit of the auxiliary power supply will generate input current harmonics, which will reduce the power factor at the input end. An additional PFC correction circuit needs to be configured to reduce the impact, which increases the circuit design and cost; (3) Limited start-up performance: The PFC correction circuit will increase the start-up time of the auxiliary power supply, thereby affecting the one-second start-up technical indicator of the dimmer.

[0004] In summary, the use of AC power supply in the existing technology leads to complex power supply circuit design, and the PFC device introduced to solve harmonic problems creates a design contradiction with the requirement for fast start-up. Utility Model Content

[0005] This invention provides an auxiliary power supply device based on a flyback converter, which solves the problems of complex power supply circuits and insufficient one-second start-up performance in AC power supply mode.

[0006] This utility model is achieved through the following technical solution:

[0007] This utility model provides an auxiliary power supply device based on a flyback converter, comprising:

[0008] transformer;

[0009] The primary circuit module is connected to the primary winding of the transformer;

[0010] The secondary circuit module is connected to the secondary winding of the transformer;

[0011] The primary-side circuit module includes an input filter circuit, an input capacitor, a first-start circuit, a VCC circuit, a flyback chip and peripheral circuits, and a switching transistor drive circuit. The input capacitor is connected to the DC bus via the input filter circuit to obtain DC power. The input capacitor, the primary winding of the transformer, and the switching transistor drive circuit form a power supply loop to provide DC voltage to the primary winding when the switching transistor drive circuit is turned on. The first-start circuit connects the input capacitor and the VCC circuit. The VCC circuit, the flyback chip and peripheral circuits, and the switching transistor drive circuit form a control loop to control the on-time of the switching transistor drive circuit.

[0012] The secondary circuit module includes an output circuit and a feedback circuit. The output circuit is connected to the secondary winding and obtains an auxiliary voltage source through the interaction between the secondary winding and the primary winding to output an auxiliary voltage to the load. The feedback circuit is connected to the output circuit and is used to obtain the output circuit signal and feed it back to the flyback chip and peripheral circuits to stabilize the output auxiliary voltage.

[0013] The auxiliary power supply device of this utility model draws power from the DC bus and regulates the output voltage through a transformer, avoiding the problem of voltage incompatibility between different models under AC power supply. Single-port power supply is compatible with the entire series of models. At the same time, the use of DC bus power supply reduces the harmonic interference of the auxiliary power supply to the AC mains power, thus reducing the AC rectification circuit, power factor correction circuit, and redundant AC power drawing circuit, making the circuit structure simpler. Through the flyback circuit design, the startup time of the auxiliary power supply is greatly reduced in the dimmer startup time, allowing the dimmer system to enter chip control faster, thereby achieving the technical specification of 1-second startup.

[0014] In some embodiments, the auxiliary power supply device further includes a port protection circuit disposed between the DC bus and the input filter circuit for protecting downstream circuits.

[0015] In some embodiments, the input filtering circuit includes a common-mode inductor L3, capacitors C16 and C17, wherein the common-mode inductor L3 includes an iron core and a first coil and a second coil wound on the iron core;

[0016] The first end of the first coil is connected to the positive terminal of the DC bus, the second end of the first coil is connected to one end of capacitor C16, the other end of capacitor C16 is connected to one end of capacitor C17 and protective ground, and the other end of capacitor C17 is connected to analog ground.

[0017] The first end of the second coil is connected to the negative terminal of the DC bus, and the second end of the second coil is connected to the other end of capacitor C17 and analog ground.

[0018] In some embodiments, the auxiliary power supply device further includes an RCD snubber circuit, which includes a resistor R18, a capacitor C10, and a diode D1.

[0019] One end of resistor R18 is connected to the first end of the primary winding, and the other end of resistor R18 is connected to the cathode of diode D1.

[0020] One end of capacitor C10 is connected to the first end of the primary winding, and the other end of capacitor C10 is connected to the cathode of diode D1. The anode of diode D1 is connected to the second end of the primary winding.

[0021] In some embodiments, the first startup circuit includes transistor Q2, MOSFET Q3, Zener diode D7, resistor R15, and resistor R16;

[0022] One end of resistor R15 is connected to the positive terminal of input capacitor C18, and the other end of resistor R15 is connected to the collector of transistor Q2, the cathode of Zener diode D7, and the gate of MOSFET Q3.

[0023] One end of resistor R16 is connected to the positive terminal of input capacitor C18, and the other end of resistor R16 is connected to the source of MOSFET Q3. The drain of MOSFET Q3 is connected to the start pin VCC of flyback chip U1.

[0024] The base of transistor Q2 is connected to the reference pin VREF of flyback chip U1, and the emitter of transistor Q2 is connected to the anode of Zener diode D7 and analog ground.

[0025] In some embodiments, the VCC circuit includes transistor Q1, diode D3, Zener diode D5, resistor R8, electrolytic capacitor C21, electrolytic capacitor C22, surface mount capacitor C1, and surface mount capacitor C2.

[0026] The base of transistor Q1 is connected to the cathode of Zener diode D5 and one end of resistor R8. The collector of transistor Q1 is connected to the other end of resistor R8, the cathode of diode D3, the positive terminal of electrolytic capacitor C22 and one end of surface mount capacitor C1. The emitter of transistor Q1 is connected to the start pin VCC of flyback chip U1, the positive terminal of electrolytic capacitor C21 and one end of surface mount capacitor C2.

[0027] The anode of diode D3 is connected to the first end of the auxiliary winding of the transformer. The second end of the auxiliary winding is connected to the negative terminal of electrolytic capacitor C21, the negative terminal of electrolytic capacitor C22, the other end of surface mount capacitor C1, the other end of surface mount capacitor C2, the anode of Zener diode D5, and analog ground.

[0028] In some embodiments, the switching transistor driving circuit includes a MOSFET Q4, a diode D2, and resistors R2, R6, R7, and R21;

[0029] The source of MOSFET Q4 is connected to the second terminal of the primary winding;

[0030] The drain of MOSFET Q4 is connected to the current sensing pin ISNS of flyback chip U1, and is also connected in series with resistor R21 to analog ground;

[0031] The gate of MOSFET Q4 is connected to the anode of diode D2, one end of resistor R7, and one end of resistor R2. The cathode of diode D2 and the other end of resistor R7 are connected in series with resistor R6 and then connected to the drive output pin OUT of flyback chip U1. The other end of resistor R2 is connected to analog ground.

[0032] In some embodiments, the flyback chip and peripheral circuitry include a flyback chip U1, a diode D4, and resistors R1, R3, R5 and surface mount capacitors C3, C4, C5, C11, C13.

[0033] The start-up pin VCC of the flyback chip U1 is connected in series with the surface-mount capacitor C5 and then connected to analog ground;

[0034] The ground pin GND of the flyback chip U1 is connected in series with the surface-mount capacitor C4 and then connected to the reference pin VREF.

[0035] The compensation pin COMP of the flyback chip U1 is connected in series with two diodes D4 and then connected to the reference pin VREF. The middle connection point of the two diodes D4 is connected in series with a surface-mount capacitor C3 and then connected to the analog ground. A resistor R1 is also connected in series between the surface-mount capacitor C3 and the reference pin VREF.

[0036] The oscillation pin RT / CT of the flyback chip U1 is connected to ground after being connected in series with a surface-mount capacitor C13. The oscillation pin is also connected to the reference pin VREF after being connected in series with a resistor R6.

[0037] The current sensing pin ISNS of the flyback chip U1 is connected to the drain of the MOSFET Q4 after being connected in series with resistor R3. The current sensing pin is also connected in series with surface-mount capacitor C11 and then to analog ground.

[0038] In some embodiments, the output circuit includes a secondary rectifier circuit and a π-type filter circuit, used to rectify and filter the output voltage of the secondary winding before outputting it.

[0039] In some embodiments, the feedback loop circuit includes resistors R17, R20, R4, R22, and R19, surface mount capacitors C12, C6, and C14, optocoupler U3, and voltage regulator chip U2.

[0040] One end of resistor R17 and one end of resistor R20 are respectively connected to the two ends of the filter inductor L2 in the π-type filter circuit;

[0041] The other end of resistor R7 is connected to the anode of the LED of optocoupler U3 and one end of resistor R4. The other end of resistor R4 is connected to the cathode of LED, one end of surface mount capacitor C12, one end of resistor R12 and the output pin of voltage regulator chip U2.

[0042] The other end of resistor R20 is connected to the other end of surface mount capacitor C12, one end of surface mount capacitor C8, the ground pin of voltage regulator chip U2, and resistor R19. The other end of surface mount capacitor C8 is connected to the other end of resistor R22, and the other end of resistor R19 is connected to the input pin of voltage regulator chip U2 and grounded.

[0043] The collector of the phototransistor in optocoupler U3 is connected to one end of the surface-mount capacitor C14 and the compensation pin COMP of the flyback chip, while the emitter of the phototransistor is connected to the other end of the surface-mount capacitor C14 and analog ground.

[0044] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0045] By adopting DC bus power supply combined with wide-range voltage input, the auxiliary power supply startup time is greatly reduced in the dimmer startup time, allowing the dimmer system to enter chip control more quickly and achieving 1-second startup of the dimmer.

[0046] It reduces AC rectifier circuits, power factor correction circuits, and redundant AC power supply circuits, thus lowering circuit costs. At the same time, high reliability reduces equipment failure and maintenance costs, thereby lowering the overall application cost.

[0047] By using DC bus power supply, harmonic interference from auxiliary power supply to AC mains power is reduced;

[0048] The circuit uses high-voltage MOSFETs, which reduces primary-side current and switching losses compared to a flyback power supply of the same power, thus improving efficiency. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the exemplary embodiments of this utility model, the drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this utility model and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0050] Figure 1 A schematic diagram of an auxiliary power supply device based on a flyback converter according to an embodiment of the present invention is shown.

[0051] Figure 2A circuit schematic diagram of a primary-side circuit module according to an embodiment of the present invention is shown;

[0052] Figure 3 The diagram shows a circuit schematic of a secondary circuit module according to an embodiment of the present invention. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are only used to explain this utility model and are not intended to limit this utility model.

[0054] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims, and accompanying drawings of this utility model are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to other steps or units inherent in the device.

[0055] The terminology used in the various embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of this application pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of this application.

[0056] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to implement the present invention. In other embodiments, well-known structures, circuits, materials, or methods are not specifically described in order to avoid obscuring the present invention.

[0057] This invention provides an auxiliary power supply device based on a flyback converter. By using DC bus power supply combined with a wide-range voltage input, the startup time of the auxiliary power supply is greatly reduced during the dimmer startup time. It also features a simple circuit structure and high power supply efficiency, thereby reducing circuit costs.

[0058] Please see Figures 1-3 As shown, Figure 1 This is a circuit module schematic diagram of the auxiliary power supply device based on a flyback converter according to this utility model. Figure 2 , Figure 3 The circuit diagrams for the primary circuit module and the secondary circuit module, respectively, are shown below. The auxiliary power supply device based on the flyback converter in this embodiment is applied to a dimmer, but can also be applied to other devices. The auxiliary power supply device includes: a transformer T1, a primary circuit module 100 connected to the primary winding of the transformer, and a secondary circuit module 200 connected to the secondary winding of the transformer.

[0059] The primary circuit module 100 includes an input filter circuit 101, an input capacitor 102, a first-start circuit 103, a VCC circuit 104, a flyback chip and peripheral circuits 105, and a switching transistor drive circuit 106. Specifically, the input filter circuit 101 is connected to the DC bus, and its function is to reduce switching noise pollution to the power grid and protect the circuit from transient interference from the power grid. The input capacitor 102 is connected to the rear end of the input filter circuit 101. The positive terminal of the input capacitor 102 is connected to one end of the primary winding of the transformer T1, and the negative terminal of the input capacitor 102 is grounded. The function of the input capacitor is to store and transfer energy. In the power supply auxiliary device, the input is powered by the bus of the power section, passes through the input filter circuit, enters the input capacitor, provides power to the transformer T1, and is then transmitted to the secondary circuit module 200 through the transformer T1 to provide low-voltage power to the dimmer system.

[0060] In the primary circuit module 100, the input capacitor 102, the primary winding of the transformer, and the switching transistor drive circuit 105 form a power supply loop, while the VCC circuit, the flyback chip and its peripheral circuits, and the switching transistor drive circuit form a control loop. The switching transistor drive circuit is turned on or off under the control of the flyback chip and its peripheral circuits. When the switching transistor drive circuit 104 is on, the primary winding is energized, and the energizer is transmitted to the secondary circuit module 200 through the secondary winding.

[0061] The initial startup circuit 103 is connected to the positive terminal of the input capacitor 102 and the input terminal of the VCC circuit 104. When the initial startup circuit is turned on, the VCC circuit is turned on, the flyback chip and peripheral circuits are powered on, and the conduction time of the switching transistor drive circuit 105 is controlled. When the switching transistor drive circuit is turned on, the transformer stores energy. When the switching transistor drive circuit is turned off, the magnetic field energy is coupled to the secondary winding through the transformer, and the on / off control provides a continuous output voltage to the secondary circuit module 200.

[0062] The secondary circuit module 200 includes an output circuit and a feedback circuit. The output circuit is connected to the secondary winding of transformer T1, and obtains a stable auxiliary voltage source through the mutual inductance between the secondary and primary windings, thereby outputting an auxiliary voltage to the load. The feedback circuit is connected to the output circuit and is used to obtain the output circuit signal from the output circuit and feed it back to the flyback chip and peripheral circuits to adjust the control signals output by the flyback chip and peripheral circuits, thereby achieving a stable auxiliary voltage output.

[0063] In some embodiments, the auxiliary power supply device further includes a port protection circuit 107. The port protection circuit 107 is disposed between the DC bus and the input filter circuit 101 to suppress inrush current and protect downstream circuits.

[0064] See Figure 2 As shown, the port protection circuit 107 consists of resistor R10 and NTC resistor R12 connected to the positive terminal BUS+ and negative terminal BUS- of the DC bus, respectively. The DC bus output is input to the filter circuit 101 through resistor R10 and NTC resistor R12.

[0065] In some implementations, the input filter circuit 101 includes a common-mode inductor L3, capacitors C16 and C17.

[0066] The common-mode inductor L3 includes an iron core and a first coil and a second coil wound on the iron core. The first end of the first coil is connected to the positive terminal BUS+ of the DC bus, and the second end of the first coil is connected to one end of capacitor C16. The other end of capacitor C16 is connected to one end of capacitor C17 and protective ground PGND. The other end of capacitor C17 is connected to analog ground AGND. The first end of the second coil is connected to the negative terminal BUS- of the DC bus, and the second end of the second coil is connected to the other end of capacitor C17 and analog ground AGND.

[0067] Filtering circuits can reduce the pollution of the power grid by switching noise, while protecting the circuit from transient interference from the power grid.

[0068] In some embodiments, the auxiliary power supply device also includes an RCD snubber circuit 108. When the switching transistor drive circuit 105 is turned off, the leakage inductance energy is dissipated by the RCD snubber circuit, preventing voltage spikes from damaging the switching transistor.

[0069] The RCD snubber circuit 108 includes a resistor R18, a capacitor C10, and a diode D1. One end of the resistor R18 is connected to the first end of the primary winding of the transformer, and the other end of the resistor R18 is connected to the cathode of the diode D1. One end of the capacitor C10 is connected to the first end of the primary winding, and the other end of the capacitor C10 is connected to the cathode of the diode D1. The anode of the diode D1 is connected to the second end of the primary winding.

[0070] In some implementations, the first startup circuit 103 includes a transistor Q2, a MOSFET Q3, a Zener diode D7, a resistor R15, and a resistor R16.

[0071] One end of resistor R15 is connected to the positive terminal of input capacitor C18, and the other end of resistor R15 is connected to the collector of transistor Q2, the cathode of Zener diode D7, and the gate of MOSFET Q3.

[0072] One end of resistor R16 is connected to the positive terminal of input capacitor C18, and the other end of resistor R16 is connected to the source of MOSFET Q3. The drain of MOSFET Q3 is connected to the start pin VCC of flyback chip U1.

[0073] The base of transistor Q2 is connected to the reference pin VREF of flyback chip U1, and the emitter of transistor Q2 is connected to the anode of Zener diode D7 and analog ground AGND.

[0074] The initial startup circuit only operates briefly in the initial stage, providing the initial startup voltage to the flyback chip when the power supply is first turned on. Subsequently, the VCC circuit generates a stable VCC voltage to power the flyback chip, shortening the startup time.

[0075] In some implementations, the VCC circuit 104 includes a transistor Q1, a diode D3, a Zener diode D5, a resistor R8, an electrolytic capacitor C21, an electrolytic capacitor C22, a surface mount capacitor C1, and a surface mount capacitor C2.

[0076] The base of transistor Q1 is connected to the cathode of Zener diode D5 and one end of resistor R8. The collector of transistor Q1 is connected to the other end of resistor R8, the cathode of diode D3, the positive terminal of electrolytic capacitor C22, and one end of surface-mount capacitor C1. The emitter of transistor Q1 is connected to the start-up pin VCC of flyback chip U1, the positive terminal of electrolytic capacitor C21, and one end of surface-mount capacitor C2.

[0077] The anode of diode D3 is connected to the first end of the auxiliary winding of the transformer. The second end of the auxiliary winding is connected to the negative terminal of electrolytic capacitor C21, the negative terminal of electrolytic capacitor C22, the other end of surface mount capacitor C1, the other end of surface mount capacitor C2, the anode of Zener diode D5, and analog ground AGND.

[0078] After the first startup circuit is turned on, MOSFET Q3 is turned on, and the voltage is limited by Zener diode D7, briefly supplying power to the VCC pin of flyback chip U1. The flyback circuit starts to work, and the VCC circuit is powered by the auxiliary winding of the transformer, providing continuous power to the VCC pin of flyback chip U1.

[0079] In some embodiments, the switching transistor drive circuit 105 includes a MOSFET Q4, a diode D2, and resistors R2, R6, R7, and R21. The source of the MOSFET Q4 is connected to the second terminal of the primary winding; the drain of the MOSFET Q4 is connected to the current detection pin ISNS of the flyback chip U1, and is also connected in series with resistor R21 to analog ground AGND; the gate of the MOSFET Q4 is connected to the anode of the diode D2, one end of resistor R7, and one end of resistor R2; the cathode of the diode D2 and the other end of resistor R7 are connected in series with resistor R6 and then connected to the drive output pin OUT of the flyback chip U1; the other end of resistor R2 is connected to analog ground AGND.

[0080] The flyback chip U1 and its peripheral circuitry control the switching frequency and duty cycle of the MOSFET Q4, thereby regulating the energy transfer process from the primary side to the secondary side. The switching transistor driver circuit drives the switching action of the MOSFET Q4 to ensure efficient power conversion.

[0081] In some embodiments, the flyback chip and peripheral circuit 106 includes a flyback chip U1 and its peripheral circuit, the peripheral circuit including the flyback chip U1, diode D4, and resistors R1, R3, R5 and surface mount capacitors C3, C4, C5, C11, C13.

[0082] The start-up pin VCC of the flyback chip U1 is connected in series with the surface-mount capacitor C5 and then connected to analog ground.

[0083] The ground pin GND of the flyback chip U1 is connected in series with a surface-mount capacitor C4 and then connected to the reference pin VREF.

[0084] The compensation pin COMP of the flyback chip U1 is connected in series with two diodes D4 and then connected to the reference pin VREF. The midpoint of the connection between the two diodes D4 is connected in series with a surface-mount capacitor C3 and then connected to analog ground. A resistor R1 is also connected in series between the surface-mount capacitor C3 and the reference pin VREF.

[0085] The oscillation pin RT / CT of the flyback chip U1 is connected to ground via a surface-mount capacitor C13 in series, and the oscillation pin is also connected to the reference pin VREF via a resistor R6 in series.

[0086] The current sensing pin ISNS of the flyback chip U1 is connected to the drain of the MOSFET Q4 after being connected in series with resistor R3. The current sensing pin is also connected in series with surface-mount capacitor C11 and then connected to analog ground AGND.

[0087] In some implementations, the output circuit includes a secondary rectifier circuit 201 and a π-type filter circuit 202. The secondary rectifier circuit 201 is used to rectify the output voltage of the secondary winding and output it, and the π-type filter circuit 202 is used to filter the rectified output voltage and output it.

[0088] like Figure 3 As shown, the secondary rectifier circuit 201 consists of resistor R9, diode FD6, surface mount capacitor C7, and capacitor C15. The π-type filter circuit 202 includes electrolytic capacitors C15 and C20, surface mount capacitors C9 and C8, inductor L2, resistor R11, and common mode inductor L1. Transformer T1 and surface mount capacitor C23 form a transformer circuit.

[0089] In some implementations, the feedback loop circuit 203 includes resistors R17, R20, R4, R22, and R19, surface mount capacitors C12, C6, and C14, optocoupler U3, and voltage regulator chip U2.

[0090] One end of resistor R17 and one end of resistor R20 are respectively connected to the two ends of the filter inductor L2 of the π-type filter circuit.

[0091] The other end of resistor R7 is connected to the anode of the LED of optocoupler U3 and one end of resistor R4. The other end of resistor R4 is connected to the cathode of LED, one end of surface mount capacitor C12, one end of resistor R12 and the output pin of voltage regulator chip U2.

[0092] The other end of resistor R20 is connected to the other end of surface mount capacitor C12, one end of surface mount capacitor C8, the ground pin of voltage regulator chip U2, and one end of resistor R19. The other end of surface mount capacitor C8 is connected to the other end of resistor R22, and the other end of resistor R19 is connected to the input pin of voltage regulator chip U2 and grounded.

[0093] The collector of the phototransistor in optocoupler U3 is connected to one end of the surface-mount capacitor C14 and the compensation pin COMP of the flyback chip, while the emitter of the phototransistor is connected to the other end of the surface-mount capacitor C14 and the analog ground AGND.

[0094] The feedback loop circuit monitors the output voltage and transmits the feedback signal to the flyback chip U1 through the optocoupler U3. The flyback chip U1 adjusts the switching frequency and duty cycle of the control MOSFET Q4 to maintain a stable output voltage.

[0095] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. An auxiliary power supply device based on a flyback converter, characterized in that, include: transformer; The primary circuit module is connected to the primary winding of the transformer; The secondary circuit module is connected to the secondary winding of the transformer; The primary-side circuit module includes an input filter circuit, an input capacitor, a first-start circuit, a VCC circuit, a flyback chip and peripheral circuits, and a switching transistor drive circuit. The input capacitor is connected to the DC bus via the input filter circuit to obtain DC power. The input capacitor, the primary winding of the transformer, and the switching transistor drive circuit form a power supply loop to provide DC voltage to the primary winding when the switching transistor drive circuit is turned on. The first-start circuit connects the input capacitor and the VCC circuit. The VCC circuit, the flyback chip and peripheral circuits, and the switching transistor drive circuit form a control loop to control the on-time of the switching transistor drive circuit. The secondary circuit module includes an output circuit and a feedback circuit. The output circuit is connected to the secondary winding and obtains an auxiliary voltage source through the interaction between the secondary winding and the primary winding to output an auxiliary voltage to the load. The feedback circuit is connected to the output circuit and is used to obtain the output circuit signal and feed it back to the flyback chip and peripheral circuits to stabilize the output auxiliary voltage.

2. The auxiliary power supply device based on a flyback converter according to claim 1, characterized in that, The auxiliary power supply device also includes a port protection circuit, which is disposed between the DC bus and the input filter circuit to protect the downstream circuit.

3. The auxiliary power supply device based on a flyback converter according to claim 1 or 2, characterized in that, The input filter circuit includes a common-mode inductor L3, capacitors C16 and C17, and the common-mode inductor L3 includes an iron core and a first coil and a second coil wound on the iron core. The first end of the first coil is connected to the positive terminal of the DC bus, the second end of the first coil is connected to one end of capacitor C16, the other end of capacitor C16 is connected to one end of capacitor C17 and protective ground, and the other end of capacitor C17 is connected to analog ground. The first end of the second coil is connected to the negative terminal of the DC bus, and the second end of the second coil is connected to the other end of capacitor C17 and analog ground.

4. The auxiliary power supply device based on a flyback converter according to claim 1, characterized in that, The auxiliary power supply device also includes an RCD absorption circuit, which includes a resistor R18, a capacitor C10, and a diode D1. One end of resistor R18 is connected to the first end of the primary winding, and the other end of resistor R18 is connected to the cathode of diode D1. One end of capacitor C10 is connected to the first end of the primary winding, and the other end of capacitor C10 is connected to the cathode of diode D1. The anode of diode D1 is connected to the second end of the primary winding.

5. The auxiliary power supply device based on a flyback converter according to claim 1, characterized in that, The first startup circuit includes transistor Q2, MOSFET Q3, Zener diode D7, resistor R15, and resistor R16; One end of resistor R15 is connected to the positive terminal of input capacitor C18, and the other end of resistor R15 is connected to the collector of transistor Q2, the cathode of Zener diode D7, and the gate of MOSFET Q3. One end of resistor R16 is connected to the positive terminal of input capacitor C18, and the other end of resistor R16 is connected to the source of MOSFET Q3. The drain of MOSFET Q3 is connected to the start pin VCC of flyback chip U1. The base of transistor Q2 is connected to the reference pin VREF of flyback chip U1, and the emitter of transistor Q2 is connected to the anode of Zener diode D7 and analog ground.

6. The auxiliary power supply device based on a flyback converter according to claim 1, characterized in that, The VCC circuit includes transistor Q1, diode D3, Zener diode D5, resistor R8, electrolytic capacitor C21, electrolytic capacitor C22, surface mount capacitor C1, and surface mount capacitor C2. The base of transistor Q1 is connected to the cathode of Zener diode D5 and one end of resistor R8. The collector of transistor Q1 is connected to the other end of resistor R8, the cathode of diode D3, the positive terminal of electrolytic capacitor C22 and one end of surface mount capacitor C1. The emitter of transistor Q1 is connected to the start pin VCC of flyback chip U1, the positive terminal of electrolytic capacitor C21 and one end of surface mount capacitor C2. The anode of diode D3 is connected to the first end of the auxiliary winding of the transformer. The second end of the auxiliary winding is connected to the negative terminal of electrolytic capacitor C21, the negative terminal of electrolytic capacitor C22, the other end of surface mount capacitor C1, the other end of surface mount capacitor C2, the anode of Zener diode D5, and analog ground.

7. The auxiliary power supply device based on a flyback converter according to claim 1, characterized in that, The switching transistor drive circuit includes a MOSFET Q4, a diode D2, and resistors R2, R6, R7, and R21. The source of MOSFET Q4 is connected to the second terminal of the primary winding; The drain of MOSFET Q4 is connected to the current sensing pin ISNS of flyback chip U1, and is also connected in series with resistor R21 to analog ground; The gate of MOSFET Q4 is connected to the anode of diode D2, one end of resistor R7, and one end of resistor R2. The cathode of diode D2 and the other end of resistor R7 are connected in series with resistor R6 and then connected to the drive output pin OUT of flyback chip U1. The other end of resistor R2 is connected to analog ground.

8. The auxiliary power supply device based on a flyback converter according to claim 7, characterized in that, The flyback chip and peripheral circuitry include flyback chip U1, diode D4, resistors R1, R3, R5, and surface mount capacitors C3, C4, C5, C11, and C13. The start-up pin VCC of the flyback chip U1 is connected in series with the surface-mount capacitor C5 and then connected to analog ground; The ground pin GND of the flyback chip U1 is connected in series with the surface-mount capacitor C4 and then connected to the reference pin VREF. The compensation pin COMP of the flyback chip U1 is connected in series with two diodes D4 and then connected to the reference pin VREF. The middle connection point of the two diodes D4 is connected in series with a surface-mount capacitor C3 and then connected to the analog ground. A resistor R1 is also connected in series between the surface-mount capacitor C3 and the reference pin VREF. The oscillation pin RT / CT of the flyback chip U1 is connected to ground after being connected in series with a surface-mount capacitor C13. The oscillation pin is also connected to the reference pin VREF after being connected in series with a resistor R6. The current sensing pin ISNS of the flyback chip U1 is connected to the drain of the MOSFET Q4 after being connected in series with resistor R3. The current sensing pin is also connected in series with surface-mount capacitor C11 and then to analog ground.

9. The auxiliary power supply device based on a flyback converter according to claim 1, characterized in that, The output circuit includes a secondary rectifier circuit and a π-type filter circuit, which are used to rectify and filter the output voltage of the secondary winding before outputting it.

10. The auxiliary power supply device based on a flyback converter according to claim 9, characterized in that, The feedback loop circuit includes resistors R17, R20, R4, R22, and R19, surface mount capacitors C12, C6, and C14, optocoupler U3, and voltage regulator chip U2. One end of resistor R17 and one end of resistor R20 are respectively connected to the two ends of the filter inductor L2 in the π-type filter circuit; The other end of resistor R7 is connected to the anode of the LED of optocoupler U3 and one end of resistor R4. The other end of resistor R4 is connected to the cathode of LED, one end of surface mount capacitor C12, one end of resistor R12 and the output pin of voltage regulator chip U2. The other end of resistor R20 is connected to the other end of surface mount capacitor C12, one end of surface mount capacitor C8, the ground pin of voltage regulator chip U2, and resistor R19. The other end of surface mount capacitor C8 is connected to the other end of resistor R22, and the other end of resistor R19 is connected to the input pin of voltage regulator chip U2 and grounded. The collector of the phototransistor in optocoupler U3 is connected to one end of the surface-mount capacitor C14 and the compensation pin COMP of the flyback chip, while the emitter of the phototransistor is connected to the other end of the surface-mount capacitor C14 and analog ground.

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