Switching power supply

Abstract

The application provides a switching power supply, comprising: a primary side electric energy conversion unit, the primary side electric energy conversion unit comprising a first input end and a first output end, the primary side electric energy conversion unit receiving alternating current through the first input end for conversion processing to output pulse electric energy through the first output end; a transformer and a first capacitor, the transformer comprising a primary winding and a secondary winding, the primary winding being electrically connected with the first output end, the first capacitor being connected in parallel with the primary winding, the transformer receiving pulse electric energy through the primary winding for isolated transmission and voltage conversion to output pulse electric energy through the secondary winding; and a secondary side electric energy conversion unit, the secondary side electric energy conversion unit comprising a second input end and a second output end, the secondary side electric energy conversion unit being used for receiving pulse electric energy through the second input end, converting the pulse electric energy into direct current electric energy and outputting the direct current electric energy through the second output end. The switching power supply provided by the application can reduce the resonance phenomenon of the resonance circuit in the primary side electric energy conversion unit.

Description

Technical Field

[0001] This application relates to the field of power conversion equipment technology, and more particularly to a switching power supply. Background Technology

[0002] In the field of switching power supplies, the energy conversion efficiency of the power supply can be improved by controlling the high-frequency switching of the switching transistor. However, during the high-frequency switching process, the switching transistor will inevitably excite resonance in the circuit, resulting in high-frequency ringing.

[0003] High-frequency ringing not only increases the switching losses of the switching transistors, leading to a decrease in power supply efficiency, but also radiates strong electromagnetic interference, affecting the normal operation of surrounding electronic equipment. At the same time, the instantaneous high voltage generated by ringing may accelerate the aging of the switching transistors and surrounding components, and even cause circuit malfunctions, posing a significant challenge to the stability and reliability of the switching power supply. Utility Model Content

[0004] In view of the above, this application provides a switching power supply to solve the problem of resonance phenomenon in switching power supplies.

[0005] The first aspect of this application provides a switching power supply, comprising: a primary-side power conversion unit, the primary-side power conversion unit including a first input terminal and a first output terminal, the primary-side power conversion unit receiving AC power through the first input terminal and performing conversion processing to output pulsed power through the first output terminal; a transformer and a first capacitor, the transformer including a primary winding and a secondary winding, the primary winding being electrically connected to the first output terminal, the first capacitor being connected in parallel with the primary winding, the transformer receiving pulsed power through the primary winding for isolated transmission and voltage transformation to output pulsed power through the secondary winding; and a secondary-side power conversion unit, the secondary-side power conversion unit including a second input terminal and a second output terminal, the second input terminal being electrically connected to the secondary winding, the secondary-side power conversion unit being used to receive pulsed power through the second input terminal, convert the pulsed power into DC power, and output it through the second output terminal.

[0006] As an optional implementation, the capacitance of the first capacitor is greater than or equal to 47 picofarads and less than or equal to 100 picofarads.

[0007] As an optional implementation, the switching power supply also includes a second capacitor, which is connected in parallel with the secondary winding.

[0008] As an optional implementation, the capacitance of the second capacitor is greater than or equal to 1 nanofarad and less than or equal to 10 nanofarads.

[0009] As an optional implementation, the primary-side power conversion unit includes: a conversion circuit that receives AC power through a first input terminal and converts it to output pulsed power through a first output terminal; an auxiliary winding and a diode, the auxiliary winding being wound on the magnetic core of the primary winding, the auxiliary winding including a third output terminal electrically connected to the negative terminal of the diode, the positive terminal of the diode being electrically connected to the power supply terminal of the conversion circuit, the auxiliary winding being used to provide working power to the conversion circuit; and a third capacitor connected in parallel with the diode.

[0010] As an optional implementation, the primary power conversion unit also includes a first resistor, which is connected in series between the third capacitor and the positive terminal.

[0011] As an optional implementation, the primary power conversion unit also includes a second resistor, which is connected in series between the third output terminal and the negative terminal.

[0012] As an optional implementation, the conversion circuit includes: a conversion module, which receives AC power through a first input terminal and performs conversion processing to output pulsed electrical energy through a first output terminal; a control module, whose signal output terminal is electrically connected to the control terminal of the conversion circuit, and is used to output control signals to the control terminal of the conversion module; and a power supply module, whose input terminal is connected to the first input terminal and whose output terminal is connected to the power supply terminal, and which receives AC power through the first input terminal and performs conversion processing to output starting electrical energy to the power supply terminal of the control module.

[0013] As an optional implementation, the switching power supply also includes an electromagnetic interference suppression circuit. The input terminal of the electromagnetic interference suppression circuit is used to receive external AC power, and the output terminal of the electromagnetic interference suppression circuit is electrically connected to the first input terminal of the primary power conversion unit to perform electromagnetic interference suppression processing on the AC power input to the primary power conversion unit.

[0014] As an optional implementation, the switching power supply also includes an over-temperature protection circuit. The over-temperature protection circuit includes a temperature detection terminal and a signal output terminal. The temperature detection terminal is used to detect the temperature of the secondary-side power conversion unit, and the signal output terminal is electrically connected to the first signal input terminal of the primary-side power conversion unit. When the temperature detected by the temperature detection terminal exceeds a preset threshold, the over-temperature protection circuit sends a protection signal to the primary-side power conversion unit through the first signal input terminal. The primary-side power conversion unit is used to perform AC power conversion processing according to the protection signal.

[0015] The switching power supply of this application increases the capacity of the resonant circuit by connecting the first capacitor in parallel with the primary winding of the transformer. This allows the resonant frequency and resonance phenomenon of the resonant circuit in the primary power conversion unit to be reduced through the first capacitor when the switching power supply is working. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the first module of the switching power supply provided in the embodiments of this application.

[0017] Figure 2 This is a schematic diagram of the first specific module of the switching power supply provided in the embodiments of this application.

[0018] Figure 3 This is a schematic diagram of the second module of the switching power supply provided in the embodiments of this application.

[0019] Figure 4 This is a schematic diagram of the second specific module of the switching power supply provided in the embodiments of this application.

[0020] Figure 5 This is a schematic diagram of the third module of the switching power supply provided in the embodiments of this application.

[0021] Key component symbols: Switching power supply 100, primary side power conversion unit 10, transformer 20, primary winding T1A, secondary winding T1B, first capacitor C1, second capacitor C2, secondary side power conversion unit 30, conversion circuit 11, auxiliary winding T1C, diode D3, third capacitor C3, first resistor R19, second resistor R20, conversion module 101, control module 102, power supply module 103, optocoupler U2, electromagnetic interference suppression circuit 40, over-temperature protection circuit 50, feedback control circuit 60. Detailed Implementation

[0022] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have a component that is centrally located. When a component is considered to be "set" on another component, it can be directly set on the other component or may also have a component that is centrally located.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0024] In the field of switching power supplies, the energy conversion efficiency of the power supply can be improved by controlling the high-frequency switching of the switching transistor. However, during the high-frequency switching process, the switching transistor will inevitably excite resonance in the circuit, resulting in high-frequency ringing.

[0025] High-frequency ringing not only increases the switching losses of the switching transistors, leading to a decrease in power supply efficiency, but also radiates strong electromagnetic interference, affecting the normal operation of surrounding electronic equipment. At the same time, the instantaneous high voltage generated by ringing may accelerate the aging of the switching transistors and surrounding components, and even cause circuit malfunctions, posing a significant challenge to the stability and reliability of the switching power supply.

[0026] In view of the above, this application provides a switching power supply. Please refer to [link to relevant documentation]. Figure 1 The diagram below is a schematic of a switching power supply 100 provided in an embodiment of this application. The switching power supply 100 includes a primary power conversion unit 10, a transformer 20, a first capacitor C1, and a secondary power conversion unit 30.

[0027] The primary power conversion unit 10 includes a first input terminal and a first output terminal. The primary power conversion unit 10 receives AC power through the first input terminal and performs conversion processing to output pulse power through the first output terminal. The transformer 20 includes a primary winding T1A and a secondary winding T1B. The primary winding T1A is electrically connected to the first output terminal. The first capacitor C1 is connected in parallel with the primary winding T1A. The transformer 20 receives pulse power through the primary winding T1A and performs isolation transmission and voltage transformation to output pulse power through the secondary winding T1B. The secondary power conversion unit 30 includes a second input terminal and a second output terminal. The second input terminal is electrically connected to the secondary winding T1B. The secondary power conversion unit 30 is used to receive pulse power through the second input terminal, convert the pulse power into DC power, and output it through the second output terminal.

[0028] Specifically, the primary-side power conversion unit 10 may include a rectifier bridge, a high-frequency switching circuit, and a drive circuit. The rectifier bridge converts the input AC power into a smooth DC bus voltage to power subsequent circuits. The drive circuit drives the switching transistors in the high-frequency switching circuit to turn on or off, converting DC power into high-frequency pulsed power. The secondary-side power conversion unit 30 may include a rectifier circuit, a common-mode rejection circuit, and an inductor. The rectifier circuit may consist of a group of rectifier diodes D3, used to convert the pulsed power coupled from the transformer 20 into DC power. The common-mode rejection circuit then suppresses common-mode electromagnetic interference generated by the secondary-side power conversion unit 30, preventing interference from being reverse-coupled to the primary-side power conversion unit 10 or radiated outwards, thus improving the electromagnetic compatibility of the circuit. Figure 2The diagram shows an exemplary structural schematic of the primary-side power conversion unit 10 and the secondary-side power conversion unit 30. This diagram illustrates one possible implementation of the primary-side power conversion unit 10 and the secondary-side power conversion unit 30, and is not the only limitation on their structure. Those skilled in the art can make equivalent adjustments or additions to the layout and model selection of components based on this exemplary structure without departing from the core concept of this solution. In practical applications, the first capacitor C1 can be a multilayer ceramic capacitor with a capacitance ranging from 47 picofarads (pF) to 100 picofarads (pF). In practical applications, it is not limited to this; it depends on the specific application environment, and all are within the scope of protection of this application.

[0029] When the switching power supply 100 is operating, the leakage inductance in the transformer 20 and the parasitic resistance of the switching transistor in the primary power conversion unit 10 form a resonant circuit. When the switching transistor operates, the resonant circuit will generate high-frequency ringing. This application addresses this by connecting the first capacitor C1 in parallel with the primary winding T1A of the transformer 20, and by using the formula... ,in, The resonant frequency, This is the inductance value. Given the capacitance value, the resonant frequency can be determined as follows: Inversely proportional, therefore, when the capacitance of the resonant circuit increases, As the value increases, the resonant frequency of the resonant circuit decreases.

[0030] In practical applications, wiring design can also be used to enhance energy dissipation in resonant circuits, suppress oscillation amplitude and duration, and reduce the radiation range of switching power supply 100 by changing the impedance in the circuit board traces.

[0031] The switching power supply 100 provided in this embodiment increases the capacity of the resonant circuit by connecting the first capacitor C1 in parallel with the primary winding T1A of the transformer 20, so as to reduce the resonant frequency of the resonant circuit in the primary power conversion unit 10 through the first capacitor C1 when the switching power supply 100 is working.

[0032] When the switching power supply 100 is operating and the rectifier diode D3 in the secondary power conversion unit 30 is in a high-speed switching state, the current flows sequentially through the secondary winding T1B of the transformer 20 and the secondary power conversion unit 30 to supply power to the load. When the secondary power conversion unit 30 is turned off, the current is interrupted, but at this time, the current in the inductor of the secondary power conversion unit 30 will not change abruptly, resulting in voltage spikes and ringing. Therefore, in an optional implementation, such as Figure 3 As shown, the switching power supply 100 may also include a second capacitor C2 connected in parallel with the secondary winding T1B.

[0033] Specifically, the second capacitor C2 can be a multilayer ceramic capacitor with a capacitance ranging from 1 nanofarad (nF) to 10 nanofarad (nF). In practical applications, it is not limited to this and can be determined according to the specific application environment, all of which are within the scope of protection of this application.

[0034] This application utilizes the characteristic that the current in the second capacitor C2 does not change abruptly. When the current in the secondary winding T1B suddenly increases, the second capacitor C2 is rapidly charged, converting the sudden current change into stored electric field energy, thus slowing down the rate of current change. When the current suddenly decreases, the second capacitor C2 discharges to replenish the current, preventing a sudden drop in current. Furthermore, the electric field energy stored in the second capacitor C2 buffers the induced voltage generated by the inductor, effectively providing a discharge path for voltage spikes, making voltage changes smoother and avoiding instantaneous high-voltage spikes. And from the formula... It can be seen that the second capacitor C2 increases the capacitance value of the resonant circuit in the secondary side power conversion unit 30, reduces the resonant frequency, and by adding the small-capacity second capacitor C2, absorbs several high-frequency ringing energy, weakens the noise voltage of the second output terminal, and avoids the high-frequency noise voltage in the ringing from radiating noise outward through the second output terminal, causing the radiation to exceed the standards stipulated by industry or regulations.

[0035] The switching power supply 100 provided in this embodiment increases the capacity of the resonant circuit in the secondary power conversion unit 30 by connecting the second capacitor C2 in parallel with the secondary winding T1B of the transformer 20. When the switching power supply 100 is working, the second capacitor C2 reduces the voltage spikes and ringing in the secondary power conversion unit 30, and avoids the high-frequency noise voltage in the ringing from radiating noise to the outside through the second output terminal, which would cause the radiation to exceed the standards specified by industry or regulations.

[0036] In an alternative implementation, the primary power conversion unit 10 may include a conversion circuit 11, an auxiliary winding T1C, a diode D3, and a third capacitor C33.

[0037] The conversion circuit 11 receives AC power through the first input terminal and converts it to output pulse power through the first output terminal. The auxiliary winding T1C is wound on the magnetic core of the primary winding T1A. The auxiliary winding T1C includes a third output terminal, which is electrically connected to the negative terminal of the diode D3. The positive terminal of the diode D3 is electrically connected to the power supply terminal of the conversion circuit 11. The auxiliary winding T1C is used to provide working power for the conversion circuit 11. The third capacitor C33 is connected in parallel with the diode D3.

[0038] In practical applications, the conversion circuit 11 first receives the input AC power, converts it into pulsed electrical energy, and outputs it from the first output terminal to the transformer 20. At the same time, the auxiliary winding T1C, which is wound on the magnetic core of the primary winding T1A, generates the first electrical energy through electromagnetic induction. The first electrical energy flows out from the third output terminal, and after passing through the diode D3 for unidirectional conduction, it is output to the power supply terminal of the conversion circuit 11, providing the power required for the operation of the conversion circuit 11. In addition, the third capacitor C33 can stably flow the first electrical energy through the diode D3, avoiding voltage fluctuations from affecting the operation of the conversion circuit 11.

[0039] When the voltage output from the auxiliary winding T1C is reversed and diode D3 needs to be turned off, the charge stored in diode D3 will not disappear immediately, but will form a momentary, huge reverse current. The leakage inductance and parasitic capacitance in the auxiliary winding T1C and the junction capacitance in diode D3 form a resonant circuit. The rapidly changing reverse current will cause the resonant circuit to generate a high-amplitude, high-frequency damped oscillating voltage waveform, which will then cause ringing. This application connects the third capacitor C33 in parallel with diode D3 to slow down the voltage change across diode D3 and absorb the peak energy.

[0040] Optionally, the primary-side power conversion unit 10 may further include a first resistor R19 and a second resistor R20. The first resistor R19 is connected in series between the third capacitor C33 and the positive terminal of the diode D3, and the second resistor R20 is connected in series between the third output terminal and the negative terminal of the diode D3. In practical applications, the first resistor R19 is used to dissipate the energy absorbed by the third capacitor C33, preventing damped oscillations, and the second resistor R20 is used to limit the current of the first power source, preventing excessive current output from the auxiliary winding T1C from damaging the diode D3.

[0041] The switching power supply 100 provided in this embodiment connects the third capacitor C33 in parallel with the diode D3, so as to slow down the voltage change across the diode D3, absorb peak energy, avoid ringing, and prevent the switching circuit 11 from working.

[0042] In one alternative implementation, such as Figure 4 As shown, the conversion circuit 11 may include a conversion module 101, a control module 102, and a power supply module 103.

[0043] The conversion module 101 receives AC power through its first input terminal, performs conversion processing, and outputs pulsed electrical energy through its first output terminal. The signal output terminal of the control module 102 is electrically connected to the control terminal of the conversion circuit 11, and the control module 102 is used to output control signals to the control terminal of the conversion module 101. The input terminal of the power module 103 is connected to the first input terminal, and the output terminal of the power module 103 is connected to the power supply terminal. The power module 103 receives AC power through its first input terminal, performs conversion processing, and outputs starting electrical energy to the power supply terminal of the control module 102 through the power supply terminal.

[0044] Specifically, after the control module 102 outputs a control signal to the control terminal of the conversion module 101, it can control the conversion module 101 to convert the AC power to output pulsed electrical energy to the primary winding T1A of the transformer 20. In practical applications, before the conversion circuit 11 is started, the power supply module 103 receives AC power through the first input terminal, performs conversion processing, and then outputs starting electrical energy to the power supply terminal of the control module 102 through the power supply terminal to provide starting electrical energy for the control module 102. After the conversion circuit 11 is started, the auxiliary winding T1C wound on the magnetic core of the primary winding T1A generates first electrical energy through electromagnetic induction. At this time, the control module 102 can be powered through the auxiliary winding T1C to provide a stable operating voltage for the control module 102.

[0045] Before the conversion circuit 11 is started, the power module 103 of the switching power supply 100 in this embodiment receives AC power through the first input terminal and performs conversion processing, and then outputs starting power to the power supply terminal of the control module 102 to provide starting power for the control module 102. After the conversion circuit 11 is started, power is supplied through the auxiliary winding T1C so as to use the power of the switching power supply 100 itself to provide a stable operating voltage for the control module 102 and avoid the AC power fluctuation affecting the operation of the control module 102.

[0046] In one alternative implementation, such as Figure 5 As shown, the switching power supply 100 may further include an electromagnetic interference suppression circuit 40. The input terminal of the electromagnetic interference suppression circuit 40 is used to receive external AC power, and the output terminal of the electromagnetic interference suppression circuit 40 is electrically connected to the first input terminal of the primary power conversion unit 10 to perform electromagnetic interference suppression processing on the AC power input to the primary power conversion unit 10.

[0047] In practical applications, the electromagnetic interference suppression circuit 40 is a circuit used to ensure the circuit's anti-interference capability and electromagnetic compatibility. It may include components such as common-mode inductors, X capacitors, and filter inductors. No specific limitations are made here, and the choice depends on the actual application environment. All of these are within the scope of protection of this application.

[0048] The switching power supply 100 provided in this embodiment uses an electromagnetic interference suppression circuit 40 to suppress electromagnetic interference in the AC power before outputting it to the first input terminal of the primary power conversion unit 10. This prevents external electromagnetic interference from entering the switching power supply 100 and affecting its operation, while also preventing interference generated by the switching power supply 100 itself from radiating outwards, interfering with other equipment, or causing electromagnetic compatibility problems.

[0049] In an optional implementation, the switching power supply 100 may further include an over-temperature protection circuit 50. The over-temperature protection circuit 50 includes a temperature detection terminal and a signal output terminal. The temperature detection terminal is used to detect the temperature of the secondary-side power conversion unit 30, specifically the temperature of the heating element in the secondary-side power conversion unit 30. The signal output terminal is electrically connected to the first signal input terminal of the primary-side power conversion unit 10.

[0050] Specifically, the temperature detection end is the physical connection point between the over-temperature protection circuit 50 and the secondary power conversion unit 30. In practical applications, temperature detection can be achieved through a temperature-sensitive element to convert the physical quantity of the temperature of the heating element in the secondary power conversion unit 30 into an electrical signal.

[0051] In practical applications, when the temperature detected at the temperature detection terminal exceeds a preset threshold, the over-temperature protection circuit 50 can send a protection signal to the primary-side power conversion unit 10 through the first signal input terminal. This allows the primary-side power conversion unit 10 to process the AC power according to the protection signal. For example, after receiving the protection signal, the primary-side power conversion unit 10 can stop outputting pulsed power, causing the transformer 20 to stop outputting pulsed power to the secondary-side power conversion unit 30. This prevents the secondary-side power conversion unit 30 from continuously operating and overheating, which could damage its internal circuitry. The preset threshold is the critical temperature value at which the over-temperature protection circuit 50 triggers its protection action. Its setting is based on the safe operating temperature of the heating element in the secondary-side power conversion unit 30, and is not specifically limited here.

[0052] Optionally, the signal output terminal of the over-temperature protection circuit 50 can also be connected to the first signal input terminal of the primary-side power conversion unit 10 through an isolation transmission module. This allows the electrical isolation of the isolation transmission module to convert the protection signal output by the over-temperature protection circuit 50 into a pulse signal or level signal recognizable by the primary-side power conversion unit 10, thus preventing common-mode interference between the secondary-side power conversion unit 30 and the primary-side power conversion unit 10 from affecting signal transmission reliability. Figure 3 As shown, the isolation transmission module can be the optocoupler U2 shown in the figure. In practical applications, it can also be a magnetic isolation chip or other components. No specific limitation is made here, and all are within the protection scope of this application.

[0053] The switching power supply 100 provided in this embodiment uses an over-temperature protection circuit 50 to detect the temperature of the secondary-side power conversion unit 30. When the temperature of the secondary-side power conversion unit 30 exceeds a preset threshold, the over-temperature protection circuit 50 sends a protection signal to the primary-side power conversion unit 10, enabling the primary-side power conversion unit 10 to perform AC power conversion processing according to the protection signal. This prevents the circuits or components in the secondary-side power conversion circuit 11 from being damaged by excessive temperature, thereby improving the safety and reliability of the switching power supply 100.

[0054] In an optional implementation, the switching power supply 100 may further include a feedback control circuit 60. The input terminal of the feedback control circuit 60 is electrically connected to the second output terminal, and the output terminal of the feedback control circuit 60 is electrically connected to the second signal input terminal of the primary power conversion unit 10.

[0055] The feedback control circuit 60 is used to collect the power information output by the secondary power conversion unit 30, such as current or voltage, and convert the power information into a feedback signal to be transmitted to the primary power conversion unit 10. The primary power conversion unit 10 is used to convert the AC power according to the feedback signal.

[0056] Specifically, when the feedback signal indicates that the DC power is too high, the primary-side power conversion unit 10 can reduce the duty cycle of its internal power switch or lower its switching frequency to reduce the pulse power input to the primary winding T1A. The energy transferred to the secondary-side power conversion unit 30 via magnetic coupling will also decrease accordingly, thereby causing the voltage or current of the DC power output from the secondary-side power conversion unit 30 to drop back to the target value. When the feedback signal indicates that the DC power is too low, the primary-side power conversion unit 10 can increase the duty cycle of its internal power switch or increase its switching frequency. Its switching frequency is adjusted to reduce the pulse energy input to the primary winding T1A, thereby increasing the energy received by the secondary power conversion unit 30 and causing the voltage or current of the DC power output by the secondary power conversion unit 30 to rise back to the target value. When the feedback signal indicates that the DC power is normal, the primary power conversion unit 10 maintains the current duty cycle and switching frequency of its internal power switch tube unchanged, ensuring that the conversion of AC power by the primary power conversion unit 10 is stable and that the DC power output by the secondary power conversion unit 30 remains within the target range.

[0057] Optionally, the output of the feedback control circuit 60 can also be connected to the second signal input of the primary power conversion unit 10 via an isolation transmission module. This allows the feedback signal output by the feedback control circuit 60 to be converted into a pulse or level signal recognizable by the primary power conversion unit 10 through the electrical isolation provided by the isolation transmission module. This prevents common-mode interference between the secondary power conversion unit 30 and the primary power conversion unit 10 from affecting signal transmission reliability. Figure 3 As shown, the isolation transmission module can be the optocoupler U2 shown in the figure. In practical applications, it can also be a magnetic isolation chip or other components. No specific limitation is made here, and all are within the protection scope of this application.

[0058] The switching power supply 100 provided in this embodiment uses a feedback control circuit 60 to collect the power information output by the secondary power conversion unit 30 and converts the power information into a feedback signal, which is then transmitted to the primary power conversion unit 10. This enables the primary power conversion unit 10 to dynamically adjust the pulse power output to the primary winding T1A based on the feedback signal, thereby compensating for the output deviation of the secondary power conversion unit 30 caused by load fluctuations and input voltage fluctuations in real time. This stabilizes the DC power output by the secondary power conversion unit 30 at a preset target value, forming a closed-loop control and improving the output accuracy and stability of the switching power supply 100.

[0059] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application should fall within the scope of protection claimed by this application.

Claims

1. A switching power supply, characterized in that, include: A primary-side power conversion unit includes a first input terminal and a first output terminal. The primary-side power conversion unit receives AC power through the first input terminal, performs conversion processing, and outputs pulsed power through the first output terminal. The transformer includes a primary winding and a secondary winding. The primary winding is electrically connected to the first output terminal. The first capacitor is connected in parallel with the primary winding. The transformer receives the pulsed electrical energy through the primary winding for isolated transmission and voltage transformation, so as to output the pulsed electrical energy through the secondary winding. The secondary-side power conversion unit includes a second input terminal and a second output terminal. The second input terminal is electrically connected to the secondary winding. The secondary-side power conversion unit is used to receive the pulse power through the second input terminal, convert the pulse power into DC power, and output it through the second output terminal.

2. The switching power supply according to claim 1, characterized in that, The capacitance of the first capacitor is greater than or equal to 47 picofarads and less than or equal to 100 picofarads.

3. The switching power supply according to claim 1, characterized in that, The switching power supply also includes: The second capacitor is connected in parallel with the secondary winding.

4. The switching power supply according to claim 3, characterized in that, The capacitance of the second capacitor is greater than or equal to 1 nanofarad and less than or equal to 10 nanofarads.

5. The switching power supply according to claim 1, characterized in that, The primary-side power conversion unit includes: A conversion circuit receives the alternating current through the first input terminal, performs conversion processing, and outputs the pulsed electrical energy through the first output terminal. An auxiliary winding and a diode are provided. The auxiliary winding is wound on the magnetic core of the primary winding. The auxiliary winding includes a third output terminal, which is electrically connected to the negative terminal of the diode. The positive terminal of the diode is electrically connected to the power supply terminal of the conversion circuit. The auxiliary winding is used to provide working power to the conversion circuit. The third capacitor is connected in parallel with the diode.

6. The switching power supply according to claim 5, characterized in that, The primary-side power conversion unit also includes: The first resistor is connected in series between the third capacitor and the positive terminal.

7. The switching power supply according to claim 5, characterized in that, The primary-side power conversion unit also includes: The second resistor is connected in series between the third output terminal and the negative terminal.

8. The switching power supply according to claim 5, characterized in that, The conversion circuit includes: A conversion module receives the alternating current through the first input terminal, performs conversion processing, and outputs the pulsed electrical energy through the first output terminal. A control module, wherein the signal output terminal of the control module is electrically connected to the control terminal of the conversion circuit, and the control module is used to output control signals to the control terminal of the conversion module; A power module, wherein the input terminal of the power module is connected to the first input terminal, and the output terminal of the power module is connected to the power supply terminal. The power module receives the AC power through the first input terminal, performs conversion processing, and outputs starting power to the power supply terminal of the control module through the power supply terminal.

9. The switching power supply according to claim 1, characterized in that, The switching power supply also includes: An electromagnetic interference suppression circuit is provided, wherein the input terminal of the electromagnetic interference suppression circuit is used to receive external alternating current, and the output terminal of the electromagnetic interference suppression circuit is electrically connected to the first input terminal of the primary power conversion unit to perform electromagnetic interference suppression processing on the alternating current input to the primary power conversion unit.

10. The switching power supply according to claim 1, characterized in that, The switching power supply also includes: An over-temperature protection circuit is provided, comprising a temperature detection terminal and a signal output terminal. The temperature detection terminal is used to detect the temperature of the secondary power conversion unit, and the signal output terminal is electrically connected to the first signal input terminal of the primary power conversion unit. When the temperature detected by the temperature detection terminal exceeds a preset threshold, the over-temperature protection circuit sends a protection signal to the primary side power conversion unit through the first signal input terminal. The primary side power conversion unit is used to convert the AC power according to the protection signal.

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