Flyback switching power supply

Abstract

The application provides a flyback switching power supply, comprising a transformer T1, a first control module, a second control module and a capacitor combination module; the transformer T1 comprises a primary winding and a first secondary winding coupled with the primary winding, the primary winding receives an input voltage, and the primary winding is connected with the first control module; the first secondary winding is connected with an input end of the second control module; an output end of the second control module is connected with the capacitor combination module and a load respectively; the capacitor combination module comprises a solid-state capacitor C1 and a plurality of patch capacitors connected in parallel with the solid-state capacitor C1; a positive electrode of the solid-state capacitor C1 is connected with an output end of the second control module, a load and one end of the plurality of patch capacitors; a negative electrode of the solid-state capacitor C1 and the other end of the plurality of patch capacitors are grounded. The application can share the current on the solid-state capacitor through the patch capacitors, reduce the loss generated by the ESR of the solid-state capacitor, and improve the power supply efficiency.

Description

Technical Field

[0001] This application relates to the field of switching power supply technology, and in particular to a flyback switching power supply. Background Technology

[0002] With the continuous development of power supply technology, miniaturization has become a future trend, and compact structural design has become an inevitable choice. However, while this compact design brings advantages, it also brings many severe challenges to power supply efficiency optimization.

[0003] In related technologies, in order to adapt to miniaturization, the output capacitor is compressed in size, and its equivalent series resistance (ESR) increases. During the continuous charging and discharging of high-frequency current, the ESR of the output capacitor will generate losses, and the losses are proportional to the square of the current. In applications that require rapid charging and discharging, the reduction in power efficiency caused by this loss cannot be ignored. Summary of the Invention

[0004] This application provides a flyback switching power supply that reduces the losses caused by the equivalent series resistance (ESR) of the solid capacitor by distributing the current on the solid capacitor through a surface-mount capacitor, thereby improving power supply efficiency.

[0005] This application provides a flyback switching power supply, including a transformer T1, a first control module, a second control module, and a capacitor combination module; the transformer T1 includes a primary winding and a first secondary winding coupled to the primary winding, the primary winding receives an input voltage and is connected to the first control module, the first secondary winding is connected to the input terminal of the second control module, and the output terminal of the second control module is connected to the capacitor combination module and a load respectively; The capacitor combination module includes a solid capacitor C1 and multiple surface-mount capacitors connected in parallel with the solid capacitor C1. The positive terminal of the solid capacitor C1 is connected to the output terminal of the second control module, the load, and one end of the multiple surface-mount capacitors. The negative terminal of the solid capacitor C1 and the other end of the multiple surface-mount capacitors are grounded.

[0006] In some embodiments, the second control module includes a field-effect transistor Q1, a control chip U1, a resistor R1, and a capacitor C2; The field-effect transistor Q1 includes an input terminal, an output terminal, and a control terminal. The control chip U1 includes pin 1 (DRV), pin 2 (GND), pin 3 (VDD), pin 4 (VIN), pin 5 (SRC), and pin 6 (SW). The primary winding of the transformer T1 includes pins 1 and 2. The input terminal of the field-effect transistor Q1 is connected to pin 1 of the primary winding of the transformer T1, one end of the capacitor C2, pin 2 (GND) and pin 5 (SRC) of the control chip U1. The other end of the capacitor C2 is connected to pin 3 (VDD) of the control chip U1. Pin 6 (SW) of the control chip U1 is connected to one end of the resistor R1. The control terminal of the field-effect transistor Q1 is connected to pin 1 (DRV) of the control chip U1. Pin 4 (VIN) of the control chip U1 is connected to the DC power supply. The output terminal of the field-effect transistor Q1 is connected to the other end of the resistor R1, the load, the positive terminal of the solid capacitor C1 in the capacitor combination module, and one end of the multiple surface-mount capacitors in the capacitor combination module.

[0007] In some embodiments, the transformer T1 further includes a second winding coupled to the primary coil, and the second control module further includes a diode D1 and a capacitor C3; The secondary winding of the transformer T1 includes pin 3 and pin 4; The anode of diode D1 is connected to pin 3 of the secondary winding of transformer T1, and the cathode of diode D1 is connected to one end of capacitor C3 and pin VIN of control chip U1. The other end of capacitor C3 is connected to the input terminal of field-effect transistor Q1, pin 1 of the primary winding of transformer T1, pin 4 of the secondary winding of transformer T1, one end of capacitor C2, pin GND of control chip U1, and pin SRC of control chip U1.

[0008] In some embodiments, the field-effect transistor Q1 includes pins 1, 2, 3, 4, 5, 6, 7, and 8; wherein, The first, second, and third pins of the field-effect transistor Q1 are connected to serve as the input terminals of the field-effect transistor Q1. Pin 4 of the field-effect transistor Q1 serves as the control terminal of the field-effect transistor Q1; Pins 5, 6, 7 and 8 of the field-effect transistor Q1 are connected to serve as the output terminals of the field-effect transistor Q1.

[0009] In some embodiments, the flyback switching power supply further includes an input processing module. The input terminal of the input processing module is connected to the mains power. The input processing module is used to convert the mains power into DC power through rectification and filtering and output it. The input processing module is connected to the primary winding to provide an input voltage to the primary winding.

[0010] In some embodiments, the primary winding of the transformer T1 includes a fifth pin, and the input processing module includes a rectifier circuit and a filter circuit; the input terminal of the rectifier circuit is connected to the mains power, the rectifier circuit converts the mains power into direct current and outputs it, and the filter circuit includes a capacitor C4 and a capacitor C5, one end of the capacitor C4 is connected to the output terminal of the rectifier circuit, one end of the capacitor C5 is connected to the fifth pin of the primary winding of the transformer T1, and the other ends of the capacitor C4 and the other ends of the capacitor C5 are grounded.

[0011] In some embodiments, the primary winding of the transformer T1 includes a sixth pin, the first control module includes a field-effect transistor Q2, the field-effect transistor Q2 includes an input terminal, an output terminal and a control terminal, the input terminal of the field-effect transistor Q2 is connected to the sixth pin of the primary winding of the transformer T1, and the output terminal of the field-effect transistor Q2 is grounded; The control terminal of the field-effect transistor Q2 is connected to a PWM wave generating circuit. The PWM wave generating circuit is used to provide a PWM wave to the control terminal of the field-effect transistor Q2 to control the conduction and cutoff of the field-effect transistor Q2.

[0012] In some embodiments, the rectifier filter module further includes an RCD absorption circuit, the input terminal of which is connected to the output terminal of the filter circuit, and the output terminal of which is connected to the fifth pin of the primary winding of the transformer T1 and the input terminal of the field-effect transistor Q2.

[0013] In some embodiments, the RCD absorption circuit includes a capacitor C6, resistors R2, R3, R4, R5, and a diode D2; wherein one end of the capacitor C6 is connected to the output terminal of the filter circuit and one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R3, the other end of the capacitor C6 is connected to the other end of the resistor R3, one end of the resistor R4, one end of the resistor R5, the other end of the resistor R4 is connected to the other end of the resistor R5, and the cathode of the diode D2; the anode of the diode D2 is connected to the fifth pin of the primary winding of the transformer T1 and the input terminal of the field-effect transistor Q2.

[0014] In some embodiments, the field-effect transistor Q2 is an NMOS transistor, which includes a drain, a gate, and a source; wherein the drain of the NMOS transistor serves as the input terminal of the field-effect transistor Q2; the gate of the NMOS transistor serves as the control terminal of the field-effect transistor Q2; and the source of the NMOS transistor serves as the output terminal of the field-effect transistor Q2.

[0015] The flyback switching power supply of this application embodiment sets a solid capacitor C1 connected in parallel with multiple surface-mount capacitors in the capacitor combination module. This allows the capacitor combination module to respond more quickly to current changes in fast charging and discharging scenarios by utilizing the high-frequency characteristics of the surface-mount capacitors. This optimizes the charging and discharging sequence, reduces the voltage loss of the solid capacitor C1, and utilizes the low ESR of the surface-mount capacitors to help the solid capacitor C1 share the output current, reducing the output current loss of the switching power supply and thus improving power efficiency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a flyback switching power supply according to an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the structure of a flyback switching power supply according to another embodiment of this application.

[0019] Figure 3 A circuit diagram of a flyback switching power supply, which is an exemplary embodiment of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0021] This application provides a flyback switching power supply that reduces the losses caused by the equivalent series resistance (ESR) of the solid capacitor by distributing the current on the solid capacitor through a surface-mount capacitor, thereby improving power supply efficiency.

[0022] refer to Figure 1 , Figure 1 This is a schematic diagram of a flyback switching power supply according to an embodiment of this application. The flyback switching power supply includes a transformer T1, a first control module, a second control module, and a capacitor combination module. Wherein: Transformer T1 includes a primary winding and a first secondary winding coupled to the primary winding. The primary winding receives an input voltage, which is a DC voltage. The primary winding is connected to the first control module, and the first secondary winding is connected to the input terminal of the second control module. The output terminal of the second control module is connected to the capacitor combination module and the load, respectively.

[0023] The capacitor module includes a solid-state capacitor C1 and multiple surface-mount capacitors connected in parallel with it. The positive terminal of the solid-state capacitor C1 is connected to the output terminal of the second control module, the load, and one end of the multiple surface-mount capacitors. The negative terminal of the solid-state capacitor C1 and the other end of the multiple surface-mount capacitors are grounded. In practical applications, the number of surface-mount capacitors is set according to the power supply or other design requirements, and there are usually two or more.

[0024] When the flyback switching power supply of this embodiment is working, when the first control module is turned on, the first control module controls the primary winding of transformer T1 to be energized. Transformer T1 converts electrical energy into magnetic energy and stores it in the magnetic core of transformer T1. At this time, because the primary winding of transformer T1 has opposite polarity (flyback characteristic), the second control module is turned off, so that the second control module disconnects the connection between the primary winding of transformer T1 and the load. The primary winding of transformer T1 cannot supply power to the load, and the load is powered by the capacitor combination module. When the first control module is turned off, the energy stored in the magnetic core of transformer T1 is released through the primary winding, so that the second control module is turned on, transferring energy to the load, and at the same time transferring energy to the capacitor combination module to charge the capacitor combination module so that when the first control module is turned on again, it can supply power to the load through the capacitor combination module.

[0025] It should be noted that the first control module and the second control module have the same switching frequency, and the second control module is turned off when the first control module is turned on, and the second control module is turned on when the first control module is turned off.

[0026] It should also be noted that during the process of the flyback switching power supply supplying power to the load, the switching transistors are turned on and off at a high frequency. That is, in the flyback switching power supply of this application embodiment, both the first control module and the second control module are turned on and off quickly. Therefore, when charging the capacitor combination module, the high-frequency characteristics and low ESR of the surface-mount capacitors are utilized to enable the surface-mount capacitors to respond to current changes more quickly. After the surface-mount capacitors complete energy storage, the solid-state capacitor C1 will be charged. Similarly, when the capacitor combination module supplies power to the load, the surface-mount capacitors discharge before the solid-state capacitor C1.

[0027] The flyback switching power supply of this application embodiment sets a solid capacitor C1 connected in parallel with multiple surface-mount capacitors in the capacitor combination module. This allows the capacitor combination module to respond more quickly to current changes in fast charging and discharging scenarios by utilizing the high-frequency characteristics of the surface-mount capacitors. This optimizes the charging and discharging sequence, reduces the voltage loss of the solid capacitor C1, and utilizes the low ESR of the surface-mount capacitors to help the solid capacitor C1 share the output current, reducing the output current loss of the switching power supply and thus improving power efficiency.

[0028] refer to Figure 3 , Figure 3 A circuit diagram of a flyback switching power supply, which is an exemplary embodiment of this application.

[0029] In some embodiments, the second control module includes a field-effect transistor Q1, a control chip U1, a resistor R1, and a capacitor C2. The field-effect transistor Q1 includes an input terminal, an output terminal, and a control terminal. The control chip U1 includes pin 1 (DRV), pin 2 (GND), pin 3 (VDD), pin 4 (VIN), pin 5 (SRC), and pin 6 (SW). The primary winding of the transformer T1 includes pin 1 and pin 2. The input terminal of the field-effect transistor Q1 is connected to pin 1 of the primary winding of transformer T1, one end of capacitor C2, pin 2 (GND) and pin 5 (SRC) of control chip U1. The other end of capacitor C2 is connected to pin 3 (VDD) of control chip U1. Pin 6 (SW) of control chip U1 is connected to one end of resistor R1. The control terminal of the field-effect transistor Q1 is connected to pin 1 (DRV) of control chip U1. Pin 4 (VIN) of control chip U1 is connected to the DC power supply. The output terminal of the field-effect transistor Q1 is connected to the other end of resistor R1, the load, the positive terminal of solid capacitor C1 in the capacitor combination module, and one end of multiple surface-mount capacitors in the capacitor combination module.

[0030] Further, in one specific embodiment, the field-effect transistor Q1 includes pins 1, 2, 3, 4, 5, 6, 7, and 8. Pins 1, 2, and 3 of the field-effect transistor Q1 are connected to serve as the input terminal of Q1; pin 4 of Q1 serves as the control terminal; and pins 5, 6, 7, and 8 of Q1 are connected to serve as the output terminal.

[0031] Preferably, the control chip U1 is model NV9701SC01.

[0032] It should be noted that the input terminals of the field-effect transistor Q1 include pins 1, 2, and 3 connected together, and the output terminals of the field-effect transistor Q1 include pins 5, 6, 7, and 8 connected together. This is because when the field-effect transistor Q1 is turned on, the current passing through its input and output terminals is relatively large. Therefore, multiple pins are provided at both the input and output terminals of the field-effect transistor Q1 to better dissipate heat.

[0033] It should also be noted that pin 1, DRV, of control chip U1 is used to control the on or off state of MOSFET Q1; the voltage of the DC power supply connected to pin 4, VIN, of control chip U1 is set according to the voltage specified or recommended in its technical manual; pin 5, SRC, of ​​control chip U1 is used to measure the voltage at the input terminal of MOSFET Q1, and pin 6, SW, of control chip U1 is used to measure the voltage at the output terminal of MOSFET Q1. Control chip U1 detects the voltage difference between the input and output terminals of MOSFET Q1 through pins 5, SRC, and 6, and controls the on or off state of MOSFET Q1 through pin 1, DRV; capacitor C2 and resistor R1 are peripheral components of control chip U1.

[0034] When the flyback switching power supply of this embodiment is working, when the first control module is turned on, the first control module controls the primary winding of transformer T1 to be energized. Transformer T1 converts electrical energy into magnetic energy and stores it in the magnetic core of transformer T1. At this time, because the primary winding of transformer T1 has opposite polarity (flyback characteristic), pins 5 (SRC) and 6 (SW) of control chip U1 detect that the voltage difference between the input and output terminals of MOSFET Q1 does not meet the set conduction conditions. Therefore, pin 1 (DRV) of control chip U1 controls MOSFET Q1 to be turned off, so that the primary winding of transformer T1 is not connected to the load. Because the connection between the two is broken by the field-effect transistor Q1, the primary winding of transformer T1 cannot supply power to the load, and the load is powered by the capacitor combination module. When the first control module is turned off, the energy stored in the core of transformer T1 is released through the primary winding. Pins 5 (SRC) and 6 (SW) of control chip U1 detect that the voltage difference between the input and output terminals of field-effect transistor Q1 meets the set conduction conditions. Therefore, pin 1 (DRV) of control chip U1 controls the field-effect transistor Q1 to conduct, and the energy stored in the core of transformer T1 is released through the primary winding and transferred to the load and capacitor combination module through field-effect transistor Q1.

[0035] In some embodiments, reference Figure 3The transformer T1 also includes a secondary winding coupled to the primary coil, and the second control module also includes a diode D1 and a capacitor C3. The secondary winding of the transformer T1 includes a third pin and a fourth pin. The anode of the diode D1 is connected to the third pin of the secondary winding of the transformer T1, and the cathode of the diode D1 is connected to one end of the capacitor C3 and the fourth pin VIN of the control chip U1. The other end of the capacitor C3 is connected to the input terminal of the field-effect transistor Q1, the first pin of the primary winding of the transformer T1, the fourth pin of the secondary winding of the transformer T1, one end of the capacitor C2, the second pin GND of the control chip U1, and the fifth pin SRC of the control chip U1.

[0036] It should be noted that an output circuit is formed by the secondary winding of transformer T1, diode D1, and capacitor C3 to power the control chip U1. That is, a separate winding of transformer T1 is used to power the control chip U1, and the control chip U1 does not need to be connected to an additional DC power supply.

[0037] refer to Figure 2 , Figure 2 This is a schematic diagram of the structure of a flyback switching power supply according to another embodiment of this application.

[0038] In some embodiments, the flyback switching power supply further includes an input processing module. The input terminal of the input processing module is connected to the mains power, such as 220V AC power. The input processing module is used to convert the mains power into DC power through rectification and filtering and output it. The input processing module is connected to the primary winding to provide input voltage to the primary winding.

[0039] Furthermore, in one specific embodiment, reference is made to... Figure 3 The primary winding of the transformer T1 includes a fifth pin. The input processing module includes a rectifier circuit and a filter circuit. The input terminal of the rectifier circuit is connected to the mains power, and the rectifier circuit converts the mains power into DC power and outputs it. The filter circuit includes capacitors C4 and C5. One end of capacitor C4 is connected to the output terminal of the rectifier circuit, one end of capacitor C5 is connected to the fifth pin of the primary winding of the transformer T1, and the other ends of capacitors C4 and C5 are grounded.

[0040] It should be noted that any rectifier circuit that rectifies mains power into DC power in the prior art can be used as the rectifier circuit in the embodiments of this application, including but not limited to bridge rectifier circuits.

[0041] It is understandable that capacitors C4 and C5 are used to reduce ripple in the DC output of the rectifier circuit and smooth the DC voltage.

[0042] Optionally, both capacitors C4 and C5 are solid-state capacitors.

[0043] In some embodiments, reference Figure 3 The primary winding of transformer T1 includes pin 6. The first control module includes a field-effect transistor Q2. The field-effect transistor Q2 includes an input terminal, an output terminal, and a control terminal. The input terminal of the field-effect transistor Q2 is connected to pin 6 of the primary winding of transformer T1, and the output terminal of the field-effect transistor Q2 is grounded. The control terminal of the field-effect transistor Q2 is connected to a PWM wave generating circuit. The PWM wave generating circuit is used to provide a PWM wave to the control terminal of the field-effect transistor Q2 to control the conduction and cutoff of the field-effect transistor Q2.

[0044] It should be noted that any circuit capable of generating PWM waves in the prior art can be used as the PWM wave generating circuit in the embodiments of this application, and will not be described in detail here.

[0045] When the flyback switching power supply of this embodiment is working, the input processing module rectifies and filters the mains power into DC power. When the PWM wave generated by the PWM wave generator circuit controls the MOSFET Q2 to conduct, the primary winding of transformer T1 is energized. Transformer T1 converts electrical energy into magnetic energy and stores it in the core of transformer T1. At this time, because the primary winding of transformer T1 has opposite polarity (flyback characteristic), the second control module is turned off, causing the second control module to disconnect the connection between the primary winding of transformer T1 and the load. The primary winding of transformer T1 cannot supply power to the load, and the load is powered by the capacitor combination module. When the PWM wave generated by the PWM wave generator circuit controls the MOSFET Q2 to turn off, the energy stored in the core of transformer T1 is released through the primary winding, causing the second control module to conduct and transfer energy to the load. At the same time, the energy is transferred to the capacitor combination module to charge the capacitor combination module so that when the MOSFET Q2 is turned on again by the PWM wave, the capacitor combination module can supply power to the load.

[0046] In other embodiments, reference is made to... Figure 3 The first control module includes a field-effect transistor Q2 and a PWM wave generation circuit, and the second control module includes a field-effect transistor Q1, a control chip U1, a resistor R1, and a capacitor C2. The configuration and connection relationship of the first control module is consistent with that of the first control module in the above embodiments, and the configuration and connection relationship of the second control module is also consistent with that of the second control module in the above embodiments. Please refer to the description in the above embodiments; further details will not be repeated here.

[0047] In this embodiment of the flyback switching power supply, the input processing module rectifies and filters the mains power to convert it into DC power. When the PWM wave generated by the PWM wave generator circuit controls the MOSFET Q2 to conduct, the primary winding of transformer T1 is energized. Transformer T1 converts electrical energy into magnetic energy and stores it in the core of transformer T1. At this time, because the primary winding of transformer T1 has opposite polarity (flyback characteristic), pins 5 (SRC) and 6 (SW) of control chip U1 detect that the voltage difference between the input and output terminals of MOSFET Q1 does not meet the set conduction conditions. Therefore, pin 1 (DRV) of control chip U1 controls MOSFET Q1 to turn off, causing the connection between the primary winding of transformer T1 and the load to be interrupted by MOSFET Q2. When transformer T1 is disconnected, its primary winding cannot supply power to the load, and the load is powered by the capacitor module. When the PWM wave generated by the PWM wave generator circuit controls the MOSFET Q2 to turn off, the energy stored in the core of transformer T1 is released through the primary winding. Pins 5 (SRC) and 6 (SW) of control chip U1 detect that the voltage difference between the input and output terminals of MOSFET Q1 meets the set conduction conditions. Therefore, pin 1 (DRV) of control chip U1 controls MOSFET Q1 to turn on, and the energy stored in the core of transformer T1 is released through the primary winding and transferred to the load and capacitor module through MOSFET Q1, so that when the PWM wave controls MOSFET Q2 to turn on next time, the capacitor module can supply power to the load.

[0048] In some embodiments, reference Figure 3 The rectifier and filter module also includes an RCD snubber circuit. The input of the RCD snubber circuit is connected to the output of the filter circuit. The output of the RCD snubber circuit is connected to pin 5 of the primary winding of transformer T1 and the input of field-effect transistor Q2.

[0049] Further, in a specific embodiment, the RCD absorption circuit includes a capacitor C6, resistors R2, R3, R4, R5, and a diode D2; wherein, one end of capacitor C6 is connected to the output terminal of the filter circuit and one end of resistor R2, the other end of resistor R2 is connected to one end of resistor R3, the other end of capacitor C6 is connected to the other end of resistor R3, one end of resistor R4, one end of resistor R5, the other end of resistor R4 is connected to the other end of resistor R5, and the cathode of diode D2, and the anode of diode D2 is connected to the fifth pin of the primary winding of transformer T1 and the input terminal of field-effect transistor Q2.

[0050] Understandably, the RCD snubber circuit is used to suppress voltage spikes caused by the leakage inductance of transformer T1, protect MOSFET Q2 from overvoltage damage, optimize the switching waveform, reduce electromagnetic interference (EMI), and improve power supply reliability. In some embodiments, the field-effect transistor Q2 is an NMOS transistor, which includes a drain, a gate, and a source; wherein, the drain of the NMOS transistor serves as the input terminal of the field-effect transistor Q2; the gate of the NMOS transistor serves as the control terminal of the field-effect transistor Q2; and the source of the NMOS transistor serves as the output terminal of the field-effect transistor Q2.

[0051] It is understandable that when the PWM wave is high, the control MOSFET Q2 is turned on; when the PWM wave is low, the control MOSFET Q2 is turned off.

[0052] In the description of this application, it should be understood that terms such as "first" and "second" are used only to distinguish similar objects and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Unless otherwise stated, "a plurality of" means two or more.

[0053] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand this application. At the same time, those skilled in the art will find that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A flyback switching power supply, characterized in that, The system includes a transformer T1, a first control module, a second control module, and a capacitor combination module. The transformer T1 includes a primary winding and a first secondary winding coupled to the primary winding. The primary winding receives an input voltage and is connected to the first control module. The first secondary winding is connected to the input terminal of the second control module. The output terminal of the second control module is connected to the capacitor combination module and the load, respectively. The capacitor combination module includes a solid capacitor C1 and multiple surface-mount capacitors connected in parallel with the solid capacitor C1. The positive terminal of the solid capacitor C1 is connected to the output terminal of the second control module, the load, and one end of the multiple surface-mount capacitors. The negative terminal of the solid capacitor C1 and the other end of the multiple surface-mount capacitors are grounded.

2. The flyback switching power supply according to claim 1, characterized in that, The second control module includes a field-effect transistor Q1, a control chip U1, a resistor R1, and a capacitor C2; The field-effect transistor Q1 includes an input terminal, an output terminal, and a control terminal. The control chip U1 includes pin 1 (DRV), pin 2 (GND), pin 3 (VDD), pin 4 (VIN), pin 5 (SRC), and pin 6 (SW). The primary winding of the transformer T1 includes pins 1 and 2. The input terminal of the field-effect transistor Q1 is connected to pin 1 of the primary winding of the transformer T1, one end of the capacitor C2, pin 2 (GND) and pin 5 (SRC) of the control chip U1. The other end of the capacitor C2 is connected to pin 3 (VDD) of the control chip U1. Pin 6 (SW) of the control chip U1 is connected to one end of the resistor R1. The control terminal of the field-effect transistor Q1 is connected to pin 1 (DRV) of the control chip U1. Pin 4 (VIN) of the control chip U1 is connected to the DC power supply. The output terminal of the field-effect transistor Q1 is connected to the other end of the resistor R1, the load, the positive terminal of the solid capacitor C1 in the capacitor combination module, and one end of the multiple surface-mount capacitors in the capacitor combination module.

3. The flyback switching power supply according to claim 2, characterized in that, The transformer T1 also includes a second winding coupled to the primary coil, and the second control module also includes a diode D1 and a capacitor C3; The secondary winding of the transformer T1 includes pin 3 and pin 4; The anode of diode D1 is connected to pin 3 of the secondary winding of transformer T1, and the cathode of diode D1 is connected to one end of capacitor C3 and pin VIN of control chip U1. The other end of capacitor C3 is connected to the input terminal of field-effect transistor Q1, pin 1 of the primary winding of transformer T1, pin 4 of the secondary winding of transformer T1, one end of capacitor C2, pin GND of control chip U1, and pin SRC of control chip U1.

4. The flyback switching power supply according to claim 2, characterized in that, The field-effect transistor Q1 includes pins 1, 2, 3, 4, 5, 6, 7, and 8; wherein, The first, second, and third pins of the field-effect transistor Q1 are connected to serve as the input terminals of the field-effect transistor Q1. Pin 4 of the field-effect transistor Q1 serves as the control terminal of the field-effect transistor Q1; Pins 5, 6, 7 and 8 of the field-effect transistor Q1 are connected to serve as the output terminals of the field-effect transistor Q1.

5. The flyback switching power supply according to any one of claims 1-4, characterized in that, It also includes an input processing module, the input terminal of which is connected to the mains power. The input processing module is used to convert the mains power into DC power through rectification and filtering and output it. The input processing module is connected to the primary winding to provide input voltage to the primary winding.

6. The flyback switching power supply according to claim 5, characterized in that, The primary winding of the transformer T1 includes a fifth pin, and the input processing module includes a rectifier circuit and a filter circuit. The input terminal of the rectifier circuit is connected to the mains power. The rectifier circuit converts the mains power into DC power and outputs it. The filter circuit includes capacitor C4 and capacitor C5. One end of capacitor C4 is connected to the output terminal of the rectifier circuit, one end of capacitor C5 is connected to the 5th pin of the primary winding of transformer T1, and the other ends of capacitor C4 and capacitor C5 are grounded.

7. The flyback switching power supply according to claim 5, characterized in that, The primary winding of the transformer T1 includes a 6th pin. The first control module includes a field-effect transistor Q2, which includes an input terminal, an output terminal, and a control terminal. The input terminal of the field-effect transistor Q2 is connected to the 6th pin of the primary winding of the transformer T1, and the output terminal of the field-effect transistor Q2 is grounded. The control terminal of the field-effect transistor Q2 is connected to a PWM wave generating circuit. The PWM wave generating circuit is used to provide a PWM wave to the control terminal of the field-effect transistor Q2 to control the conduction and cutoff of the field-effect transistor Q2.

8. The flyback switching power supply according to claim 7, characterized in that, The rectifier filter module also includes an RCD absorption circuit. The input terminal of the RCD absorption circuit is connected to the output terminal of the filter circuit. The output terminal of the RCD absorption circuit is connected to the 5th pin of the primary winding of the transformer T1 and the input terminal of the field-effect transistor Q2.

9. The flyback switching power supply according to claim 8, characterized in that, The RCD absorption circuit includes capacitor C6, resistors R2, R3, R4, R5, and diode D2; wherein, One end of capacitor C6 is connected to the output terminal of the filter circuit and one end of resistor R2. The other end of resistor R2 is connected to one end of resistor R3. The other end of capacitor C6 is connected to the other end of resistor R3, one end of resistor R4, and one end of resistor R5. The other end of resistor R4 is connected to the other end of resistor R5 and the cathode of diode D2. The anode of diode D2 is connected to the 5th pin of the primary winding of transformer T1 and the input terminal of field-effect transistor Q2.

10. The flyback switching power supply according to claim 7, characterized in that, The field-effect transistor Q2 is an NMOS transistor, which includes a drain, a gate, and a source; wherein... The drain of the NMOS transistor serves as the input terminal of the field-effect transistor Q2; The gate of the NMOS transistor serves as the control terminal of the field-effect transistor Q2; The source of the NMOS transistor serves as the output terminal of the field-effect transistor Q2.

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