Switching power supply and electronic equipment

Abstract

The invention provides a switching power supply which comprises an energy storage circuit and a PFC circuit, the PFC circuit comprises a first winding, and the energy storage circuit comprises a second winding, an energy storage capacitor and a rectifying element; the second winding and the first winding form a first inductor, the first winding is a main winding of the first inductor, the second winding is an auxiliary winding of the first inductor, and the second winding is used for obtaining electric energy from the first winding; the rectifying element is used for rectifying the output current of the second winding; the energy storage capacitor is used for storing electric energy when the switching power supply is in a normal working state. The second winding corresponding to the first winding in the PFC circuit is used for obtaining the electric energy of the first winding, and the energy storage capacitor is used for storing the rectified electric energy when the switching power supply is in a normal working state, so that the size of the switching power supply is reduced and the loss of a power loop switching element is reduced on the premise of ensuring the power-down retention time; the scheme is simple in structure, low in cost and easy to realize. The invention further provides an electronic device.

Description

Technical Field

[0001] The present disclosure relates to the field of power electronics technology, and in particular to a switching power supply and electronic equipment. Background Art

[0002] Electronic devices such as communications equipment and servers require AC power when in use. Since AC power is directly connected to the power grid, it must cope with the various adverse effects of grid fluctuations. Generally, a single power supply must be able to maintain a stable output voltage even if the upstream power grid experiences a brief interruption of less than 20ms, allowing downstream circuits to continue functioning normally, such as saving information. Another alternative is a dual-input backup power supply method, which requires that both AC (or DC) power outputs remain intact during the switching process, ensuring normal operation of the equipment. Even after a power outage, a 20mS holdover time is typically required to ensure input power switching.

[0003] The switching power supply is equipped with a large-capacity bus capacitor as an energy storage circuit. When the power grid is briefly interrupted, the bus capacitor supplies power to the electrical equipment. However, the large-capacity bus capacitor is large in size and expensive. To solve this technical problem, the related art adds a Baby-Boost circuit inside the switching power supply and sets a switching element between the Baby-Boost circuit and the PFC (Power Factor Correction) circuit to combine the power. However, this will increase the power circuit loss. Summary of the Invention

[0004] The present disclosure provides a switching power supply and an electronic device.

[0005] In a first aspect, an embodiment of the present disclosure provides a switching power supply, comprising: an energy storage circuit and a power factor correction (PFC) circuit, wherein the PFC circuit comprises a first winding, and the energy storage circuit comprises a second winding, an energy storage capacitor, and a rectifier element;

[0006] The second winding and the first winding form a first inductor, the first winding is a main winding of the first inductor, the second winding is an auxiliary winding of the first inductor, and the second winding is used to obtain electrical energy from the first winding;

[0007] The rectifier element is used to rectify the output current of the second winding;

[0008] The energy storage capacitor is used to store the electric energy when the switching power supply is in a normal working state.

[0009] In a second aspect, an embodiment of the present disclosure provides an electronic device, comprising the switching power supply as described above.

[0010] The switching power supply in the disclosed embodiment includes an energy storage circuit and a PFC circuit. The PFC circuit includes a first winding, and the energy storage circuit includes a second winding, an energy storage capacitor, and a rectifier element. The second winding and the first winding form a first inductor, the first winding being the main winding of the first inductor, and the second winding being an auxiliary winding of the first inductor, and the second winding is used to obtain electrical energy from the first winding. The rectifier element is used to rectify the output current of the second winding. The energy storage capacitor is used to store electrical energy when the switching power supply is in normal operation. The disclosed embodiment utilizes the second winding corresponding to the first winding in the PFC circuit to obtain electrical energy from the first winding. When the switching power supply is in normal operation, the energy storage capacitor is used to store the rectified electrical energy. This can reduce the size of the switching power supply and reduce power circuit switching element losses while ensuring power-off holdover time. This solution has a simple structure, low cost, and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the accompanying drawings of the embodiments of the present disclosure:

[0012] Figure 1 Schematic diagram of a switching power supply module provided in an embodiment of the present disclosure Figure 1 ;

[0013] Figure 2 Schematic diagram of a switching power supply module provided in an embodiment of the present disclosure Figure 2 ;

[0014] Figure 3 Schematic diagram of a switching power supply module provided in an embodiment of the present disclosure Figure 3 ;

[0015] Figure 4 A schematic diagram of a switching power supply module provided in a specific embodiment of the present disclosure;

[0016] Figure 5 A circuit diagram of a switching power supply provided in the first embodiment of the present disclosure;

[0017] Figure 6 A circuit diagram of a switching power supply provided in the second embodiment of the present disclosure;

[0018] Figure 7 A circuit diagram of a switching power supply provided in the third embodiment of the present disclosure;

[0019] Figure 8 A circuit diagram of a switching power supply provided in a fourth embodiment of the present disclosure;

[0020] Figure 9 A circuit diagram of a switching power supply provided in a fifth embodiment of the present disclosure;

[0021] Figure 10 A circuit diagram of a switching power supply provided in Example 6 of the present disclosure;

[0022] Figure 11 A circuit diagram of a switching power supply provided in Example 7 of the present disclosure;

[0023] Figure 12 This is a circuit diagram of the switching power supply provided in Example 8 of the present disclosure. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0025] The present disclosure will be described more fully hereinafter with reference to the accompanying drawings, but the illustrated embodiments may be embodied in different forms, and the present disclosure should not be construed as limited to the embodiments set forth below. Rather, these embodiments are provided so that the present disclosure will be thorough and complete and will fully understand the scope of the present disclosure to those skilled in the art.

[0026] The accompanying drawings of the embodiments of the present disclosure are used to provide a further understanding of the embodiments of the present disclosure and constitute a part of the specification. Together with the detailed embodiments, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. The above and other features and advantages will become more apparent to those skilled in the art by describing the detailed embodiments with reference to the accompanying drawings.

[0027] The present disclosure may be described with reference to plan views and / or cross-sectional views by way of ideal schematic views of the present disclosure. Therefore, the exemplary illustrations may be modified according to manufacturing techniques and / or tolerances.

[0028] In the absence of conflict, the various embodiments of the present disclosure and the various features therein may be combined with each other.

[0029] The terms used in this disclosure are only used to describe specific embodiments and are not intended to limit the disclosure. As used in this disclosure, the term "and / or" includes any and all combinations of one or more related enumerated items. As used in this disclosure, the singular forms "a" and "the" are also intended to include plural forms, unless the context clearly indicates otherwise. As used in this disclosure, the terms "comprising" and "made of" specify the presence of the features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof.

[0030] Unless otherwise defined, all terms (including technical and scientific terms) used in this disclosure have the same meanings as those commonly understood by those skilled in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined in this disclosure.

[0031] The present disclosure is not limited to the embodiments shown in the drawings, but includes modifications of the configurations formed based on the manufacturing process. Therefore, the regions illustrated in the drawings have schematic properties, and the shapes of the regions shown in the drawings illustrate the specific shapes of the regions of the elements, but are not intended to be limiting.

[0032] Hold-up time refers to the time difference between when the AC power is lost and when the output voltage drops to within an accuracy of 2%. Simply put, it's the time it takes a switching power supply to maintain output after the input is removed. Energy storage capacitors store energy to power the load, thereby improving the hold-up time of a switching power supply. In related art, one approach to increasing the hold-up time of a switching power supply is to increase the capacitance of the bus capacitor in the PFC circuit. However, the bus capacitor itself is relatively large in a switching power supply. Further increasing the capacitance would increase its size, hindering the miniaturization of the switching power supply. Furthermore, the increased bus capacitor size further increases the cost. Currently, some switching power supplies incorporate a Baby-Boost circuit to address the issue of bulky capacitors. This solution requires adding a diode, switch, or other switching element between the Baby-Boost circuit and the PFC circuit to combine the power. This is equivalent to adding a switching element with conduction losses between the PFC circuit output and the bus capacitor power circuit.

[0033] In order to solve the above technical problems, in a first aspect, the embodiments of the present disclosure provide a switching power supply. Figure 1 Schematic diagram of a switching power supply module provided in an embodiment of the present disclosure Figure 1 ,like Figure 1 As shown, the switching power supply includes: an energy storage circuit 1 and a PFC circuit 2, the PFC circuit 2 includes a first winding L1-1, the energy storage circuit 1 includes a second winding L1-2, an energy storage capacitor C2 and a rectifier element; the second winding L1-2 and the first winding L1-1 form a first inductor L1, the first winding L1-1 is the main winding of the first inductor L1, the second winding L1-2 is the auxiliary winding of the first inductor L1, and the second winding L1-2 is used to obtain electrical energy from the first winding L1-1; the rectifier element is used to rectify the output current of the second winding L1-2; the energy storage capacitor C2 is used to store electrical energy when the switching power supply is in normal working state.

[0034] PFC circuit 2 is a circuit that can improve the power factor at the AC power supply end. Power factor, also known as power factor, is a physical quantity unique to AC power systems. It is the ratio of the effective power consumed by the load to its apparent power and is a dimensionless quantity between 0 and 1. PFC circuit 2 includes an input and an output. Input terminals Vin1 and Vin2 are connected to the power grid, and output terminals Vout1 and Vout2 are connected to a load (not shown). PFC circuit 2 is used to boost the voltage at the input terminal and output voltage to the load through output terminals Vout1 and Vout2 to drive the load. PFC circuit 2 includes a boost circuit, which includes a first winding L1-1, which can be used as a boost inductor. PFC circuit 2 may also include a rectifier circuit (not shown). The rectifier circuit is connected between the power grid and the boost circuit to rectify the AC current output from the power grid into DC current.

[0035] In some embodiments, the load can be a communication base station, server, switch, or other high-power electronic device. The rectifying element in the energy tank circuit 1 can be a diode. The second winding L1-2 in the energy tank circuit 1 is arranged corresponding to the first winding L1-1 in the PFC circuit 2, and the two form a first inductor L1. The first winding L1-1 serves as the main winding of the first inductor L1, transferring electrical energy to the second winding L1-2. The second winding L1-2 serves as an auxiliary winding of the first inductor L1, storing electrical energy obtained from the first winding L1-1 when the switching power supply is in normal operation, which serves as the energy source for the energy storage capacitor C2. The energy tank circuit 1 can obtain different energy storage voltages depending on the turns ratio between the second winding L1-2 and the first winding L1-1.

[0036] The switching power supply in the disclosed embodiment includes: an energy storage circuit and a power factor correction (PFC) circuit. The PFC circuit includes a first winding, and the energy storage circuit includes a second winding, an energy storage capacitor, and a rectifier element. The second winding and the first winding form a first inductor, the first winding being the main winding of the first inductor, and the second winding being an auxiliary winding of the first inductor, and the second winding is used to obtain electrical energy from the first winding. The rectifier element is used to rectify the output current of the second winding. The energy storage capacitor is used to store electrical energy when the switching power supply is in normal operation. The disclosed embodiment utilizes the second winding corresponding to the first winding in the PFC circuit to obtain electrical energy from the first winding. When the switching power supply is in normal operation, the energy storage capacitor is used to store the rectified electrical energy. This can reduce the size of the switching power supply and reduce losses in the power circuit switching elements while ensuring power-off holdover time. This solution has a simple structure, low cost, and is easy to implement.

[0037] Figure 2 Schematic diagram of a switching power supply module provided in an embodiment of the present disclosure Figure 2 ,like Figure 2As shown, in some embodiments, the switching power supply may further include a power-off holding switching circuit 3 and a bus capacitor C1, and the power-off holding switching circuit 3 is connected to the energy storage circuit 1 and the bus capacitor C1, respectively; the energy storage capacitor C2 is also used to release electrical energy to the bus capacitor C1 through the power-off holding switching circuit 3 when the switching power supply is in an abnormal working state.

[0038] The input of the power-off hold switching circuit 3 is connected to the energy storage capacitor C2 in the energy storage circuit 1, and the output of the power-off hold switching circuit 3 is connected to the bus capacitor C1 and the load (not shown). When the input terminals Vin1 and Vin2 of the PFC circuit 2 lose power, the power-off hold switching circuit 3 can output a voltage to the load to maintain load power. By matching the power-off hold switching circuit 3 with the voltage on the energy storage capacitor C2, the energy in the energy storage capacitor C2 can be released to the bus capacitor C1, and then the energy can be transferred to the load.

[0039] In some embodiments, the power-off retention switching circuit 3 may be one power-off retention switching circuit, or may be at least two power-off retention switching circuits connected in parallel.

[0040] Figure 3 Schematic diagram of a switching power supply module provided in an embodiment of the present disclosure Figure 3 ,like Figure 3 As shown, in some embodiments, the switching power supply may further include a detection control module 4, which is used to detect the operating state of the switching power supply. When the switching power supply is in an abnormal operating state, the detection control module 4 controls the power-off holding switching circuit 3 to be turned on, so that the energy storage capacitor C2 releases electrical energy to the bus capacitor C1 through the power-off holding switching circuit 3. That is, when the switching power supply is in an abnormal operating state, that is, the grid output voltage is abnormal, for example, such as when the grid voltage drops (sags), the detection control module 4 controls the power-off holding switching circuit 3 to be turned on and connected to the load, and the load is powered by the power-off holding switching circuit 3 instead of the PFC circuit 2. A grid voltage drop (sag) refers to a lack of voltage input to the AC power supply or DC power supply caused by a grid power outage or fault. It should be noted that when the switching power supply is in a normal operating state, that is, the grid output voltage is normal, the PFC circuit 2 is connected to the load and directly powers the load.

[0041] In some embodiments, the power-down holding switching circuit 3 may further include a synchronous rectification circuit ( Figure 3 (Not shown) It should be noted that when the freewheeling device is a diode, the first end of the freewheeling device serves as the diode's cathode, and the second end of the freewheeling device serves as the diode's anode. Because the switching tube has a low on-resistance, it can be used to implement synchronous rectification, reducing power loss in the rectification circuit and increasing the power of the switching power supply.

[0042] In some embodiments, the switching power supply being in an abnormal working state includes: the input voltage of the PFC circuit 2 dropping, and / or the bus voltage of the PFC circuit 2 being less than a preset threshold.

[0043] The bus voltage of the PFC circuit 2 is the voltage between the two output terminals Vout1 and Vout2 of the PFC circuit 2 , that is, the discharge voltage of the bus capacitor C1 .

[0044] Based on at least one input terminal signal of the PFC circuit 2, it is determined that the input voltage drop of the switching power supply is a first condition for judging that the switching power supply is operating abnormally. The discharge voltage of the bus capacitor C1 is lower than a certain voltage as a second condition for judging that the switching power supply is operating abnormally. When at least one of the above two conditions is met, it indicates that the switching power supply is operating abnormally. At this time, the detection control module 4 controls the energy storage capacitor C2 in the energy storage circuit 1 to release its stored electrical energy to the bus capacitor C1 through the power-off holding switching circuit 3.

[0045] In some embodiments, the PFC circuit 2 may be a single PFC circuit, or may be at least two PFC circuits connected in parallel.

[0046] In some embodiments, the energy storage circuit 1 may be a single energy storage circuit, or may be at least two energy storage circuits connected in parallel.

[0047] It should be noted that the bus capacitor C1 can be one or at least two. If the energy storage circuit 1 is at least two energy storage circuits connected in parallel, then when the switching power supply is in an abnormal operating state, the detection control module 4 controls the energy storage capacitor C2 in at least one of the energy storage circuits 1 to release its stored electrical energy to at least one bus capacitor C1 through the power-off retention switching circuit 3.

[0048] In the disclosed embodiments, the circuit topology of the PFC circuit 2 is not limited and can be any PFC circuit topology commonly used in switching power supplies, including both a traditional topology and a bridgeless PFC topology. The disclosed embodiments also do not limit the number of PFC circuits 2; a single PFC circuit can be used or two or more PFC circuits connected in parallel. In the disclosed embodiments, the input of the PFC circuit 2 is not limited to a single-phase AC input and can also be a three-phase AC input or a DC input.

[0049] In the case of a multi-parallel PFC circuit, since there are multiple first windings L1-1, an auxiliary winding L1-2 may be provided corresponding to each first winding L1-1, or one auxiliary winding L1-2 may be provided corresponding to multiple first windings L1-1.

[0050] In the embodiment of the present disclosure, the switching power supply may include one energy storage circuit 1 or multiple energy storage circuits 1. The electric energy stored in the energy storage capacitor C2 may be released to the load through one power-off holding switching circuit 3, or the electric energy stored in the energy storage capacitor C2 may be released to the load through multiple power-off holding switching circuits 3.

[0051] In some embodiments, the two ends of the rectifier element are respectively connected to the first end of the second winding L1-2 and the positive electrode of the energy storage capacitor C2; the second end of the second winding L1-2 is connected to the negative bus terminal of the PFC circuit 2, the negative electrode of the bus capacitor C1, and the negative electrode of the energy storage capacitor C2; or the second end of the second winding L1-2 is connected to the positive bus terminal of the PFC circuit 2 and the positive electrode of the bus capacitor C1, and the negative electrode of the energy storage capacitor C2 is connected to the negative bus terminal of the PFC circuit 2 and the negative electrode of the bus capacitor C1; the input end of the power-down hold switching circuit 3 is connected to the positive electrode of the energy storage capacitor C2, the output end of the power-down hold switching circuit 3 is connected to the positive electrode of the bus capacitor C1, and the negative end of the power-down hold switching circuit 3 is connected to the negative bus terminal of the PFC circuit 2. The positive bus terminal of the PFC circuit 2 is the output terminal Vout1 of the PFC circuit 2, and the negative bus terminal of the PFC circuit 2 is the output terminal Vout2 of the PFC circuit 2. Typically, the negative bus terminal of the PFC circuit 2 is grounded.

[0052] In some embodiments, when the second end of the second winding L1-2 is connected to the bus negative terminal Vout2 of the PFC circuit 2, and the turns ratio of the second winding L1-2 to the first winding L1-1 is less than or equal to 1, the voltage of the energy storage capacitor C2 is ≤ the voltage of the bus capacitor C1, and the power-off holding switching circuit 3 is a boost circuit or a buck-boost circuit.

[0053] In some embodiments, when the second end of the second winding L1-2 is connected to the bus negative terminal Vout2 of the PFC circuit 2, and the turns ratio of the second winding L1-2 to the first winding L1-1 is greater than 1, the voltage of the energy storage capacitor C2 is greater than the voltage of the bus capacitor C1, and the power-off holding switching circuit 3 is a step-down circuit or a step-up / step-down circuit.

[0054] In some embodiments, when the second end of the second winding L1-2 is connected to the bus positive terminal Vout1 of the PFC circuit 2, the voltage of the energy storage capacitor C2 is greater than the voltage of the bus capacitor C1, and the power-off holding switching circuit 3 is a step-down circuit or a step-up / step-down circuit.

[0055] In some embodiments, when there are multiple energy storage capacitors C2 and multiple bus capacitors C1, the sum of the capacitances of the energy storage capacitors C2 is greater than the sum of the capacitances of the bus capacitors C1. When there is only one energy storage capacitor C2 and one bus capacitor C1, the capacitance of the energy storage capacitor C2 is greater than that of the bus capacitor C1. When the input voltage of the PFC circuit 2 drops, the greater the capacitance of the energy storage capacitor C2, the more energy it feeds back to the input of the boost circuit, thereby more effectively maintaining a stable output voltage across the bus capacitor C1.

[0056] In addition, in the embodiment of the present disclosure, the energy transfer of the energy storage capacitor C2 is not restricted by the back-end circuit. The energy storage capacitor C2 can transfer all the energy to the bus capacitor C1, thereby reducing the total capacitance of the energy storage capacitor C2 and the bus capacitor C1, and correspondingly reducing the volume of the capacitor, thereby reducing the cost of the switching power supply.

[0057] Figure 4 The module diagram of the switching power supply provided by the specific example of the present disclosure is as follows: Figure 4 , the detection control module 4 is described in detail.

[0058] In some embodiments, the power-off holding switching circuit 3 includes at least one switch tube, which is used to control the power-off holding switching circuit 3 to be turned on or off. Figure 4 As shown, the detection and control module 4 includes an input voltage detection unit 41, an output voltage detection unit 42, and a control unit 43. The input voltage detection unit 41 is connected to both ends of an AC power source and is used to detect the input voltage of the PFC circuit 2. The AC power source is connected to the input terminals Vin1 and Vin2 of the PFC circuit 2. The output voltage detection unit 42 is connected to the positive bus terminal Vout1 and the negative bus terminal Vout2 of the PFC circuit 2, respectively, and is used to detect the bus voltage of the PFC circuit 2. The control unit 43 is connected to at least one of the switching transistors in the power-off hold switching circuit 3 and is used to control the corresponding switching transistor to conduct when the switching power supply is in an abnormal operating state.

[0059] It should be noted that, in some embodiments, the power-off holding switching circuit 3 can also be controlled to be always on, and the power-off holding output voltage is set at a value lower than the bus voltage of the PFC circuit. When the input power is lost to the voltage regulation value of the power-off holding circuit, the electric energy of the energy storage capacitor C2 is released to the bus capacitor C1.

[0060] Control unit 43 includes an output voltage detection input, and output voltage detection unit 42 includes an output voltage detection input and an output voltage detection output. The output voltage detection input of output voltage detection unit 42 is electrically connected to the negative bus terminal and the positive bus terminal of PFC circuit 2. The output voltage detection output of output voltage detection unit 42 is electrically connected to the output voltage detection input of control unit 43. Based on the voltage signal at the output voltage detection input, control unit 43 determines whether the bus voltage of PFC circuit 2 is less than a preset threshold, that is, whether the discharge voltage of bus capacitor C1 meets the second condition for abnormal operation of the switching power supply. Specifically, output voltage detection unit 42 detects the output voltage Vo of PFC circuit 2, that is, the voltage of bus capacitor C1. When control unit 43 determines that the output voltage Vo of PFC circuit 2 is less than the predetermined voltage value, it controls power-down hold switching circuit 3 to operate, releasing the energy stored in energy storage capacitor C2 in energy storage circuit 1 into bus capacitor C1, thereby maintaining a stable output voltage from bus capacitor C1 to the downstream load.

[0061] The control unit 43 also includes an input voltage detection input terminal, and the input voltage detection unit 41 also includes an input voltage detection input terminal and an input voltage detection output terminal. The input voltage detection input terminal of the input voltage detection unit 41 is electrically connected to the input terminals Vin1 and Vin2 of the PFC circuit 2. The input voltage detection output terminal of the input voltage detection unit 41 is electrically connected to the input voltage detection input terminal of the control unit 43. The control unit 43 determines whether the input voltage of the PFC circuit 2 has dropped based on the voltage signal at the input voltage detection input terminal, that is, whether the input voltage of the PFC circuit 2 meets the first condition for abnormal operation of the switching power supply. Specifically, the input voltage detection unit 41 detects the input voltage of the PFC circuit 2. When the control unit 43 determines that the input voltage of the PFC circuit has dropped, that is, the input voltage drop of the PFC circuit 2 is greater than a predetermined voltage value, the control unit 43 controls the power-down hold switching circuit 3 to operate, releasing the energy stored in the energy storage capacitor C2 in the energy storage circuit 1 to the bus capacitor C1, thereby maintaining a stable output voltage from the bus capacitor C1 to the downstream load.

[0062] The input voltage detection unit 41 and the output voltage detection unit 42 can be sampling resistors, which are simple to implement and low in cost. Other voltage detection elements can also be used for implementation, which is not limited in the embodiment of the present disclosure.

[0063] In some embodiments, the switching power supply may further include a driving circuit (not shown in the figure), which is arranged between the control unit 43 and the switching tube in the power-off retention switching circuit 3, and is used to amplify the various control signals of the control unit 43 to drive the various switching tubes in the power-off retention switching circuit 3.

[0064] When the power-down retention switching circuit 3 includes multiple switching transistors, multiple drive circuits may be provided, with the input end of each of the multiple drive circuits connected to a control signal output end of the control unit 43; and the output end of each drive circuit connected to the drive end of a switching transistor. For example, when the switching transistor is an NMOS transistor, the output end of each drive circuit is connected to the gate of the NMOS transistor.

[0065] In some embodiments, the multiple drive circuits can be implemented by one or more integrated driver chips or by separately constructed analog circuits. The connection between the control unit 43 and the drive circuits can be a multi-terminal interconnect, where the number of connection terminals depends on the number of switches in the PFC circuit 2 and the power-down hold switching circuit 3.

[0066] The following combination Figure 4 , the structure of the switching power supply is described in detail. Figure 4 As shown, the switching power supply includes: an energy storage circuit 1, a PFC circuit 2, a power-off holding switching circuit 3, a detection control module 4 and a DC-DC conversion circuit 5. The detection control module 4 includes an input voltage detection unit 41, an output voltage detection unit 42 and a control unit 43.

[0067] The input of the PFC circuit 2 is connected to an AC power source, and the output of the PFC circuit 2 is connected to the input of a DC-DC converter circuit 5. The PFC circuit 2 includes a rectifier circuit and a boost circuit. The output of the DC-DC converter circuit 5 is connected to a load to supply power to the load. The control signal output of the control unit 43 is connected to the signal input of the power-down hold switching circuit 3. The input voltage detection input of the input voltage detection unit 41 is connected to the AC power source. The input voltage detection output of the input voltage detection unit 41 is connected to the input voltage detection input of the control unit 43. The output voltage detection input of the output voltage detection unit 42 is connected to the output of the PFC circuit 2. The output voltage detection output of the output voltage detection unit 42 is connected to the output voltage detection input of the control unit 43. The PFC circuit 2 is configured for rectification, boosting, and filtering. The DC-DC converter circuit 5 is configured to convert the DC voltage output by the PFC circuit 2 into a DC voltage for supplying the load. For example, the 400V DC voltage output by the PFC circuit 2 can be stepped down to 54V to power the server (i.e., the load). The DC-DC converter circuit 5 can also be used for isolation and voltage regulation. It should be noted that the switching power supply may not include the DC-DC conversion circuit 5 . In this case, the output voltage of the PFC circuit 2 is directly supplied to the load.

[0068] The control unit 43 is used to provide control signals to the various switches in the power-failure hold switching circuit 3, controlling their operating states to ensure that the PFC circuit 2 provides a stable output voltage to the backend. When the AC power supply voltage drops and / or the bus voltage of the PFC circuit 2 falls below a preset threshold, the control unit 43 controls the release of electrical energy from the energy storage capacitor C2 to the bus capacitor C1. The control unit 43 is also used to stabilize the output of the PFC circuit 2 and the output of the power-failure hold switching circuit 3 during the discharge phase.

[0069] The two input voltage detection input terminals of the input voltage detection unit 41 are connected to the positive and negative poles of the AC power supply, respectively. The input voltage detection unit 41 is used to detect the voltage of the AC power supply and transmit the detected voltage to the control unit 43. The control unit 43 receives the positive and negative voltage signals of the AC power supply from the input voltage detection unit 41, converts them into corresponding digital signals, and determines whether an input voltage drop has occurred in the PFC circuit 2 based on the digital signals. For example, the input voltage detection unit 41 can be implemented using a voltage transformer.

[0070] One output voltage input terminal of the output voltage detection unit 42 is connected to the positive bus terminal of the PFC circuit 2, and the other output voltage input terminal of the output voltage detection unit 42 is grounded. The output voltage detection unit 42 is used to detect the DC voltage Vo output by the PFC circuit 2 and transmit the detected DC voltage Vo to the control unit 43. The control unit 43 converts the DC voltage Vo into a corresponding digital signal and compares the digital signal with a preset threshold. If the digital signal is less than the preset threshold, the control unit 43 controls the switching transistors in the power-failure holding switching circuit 3 to turn on to stabilize the output voltage.

[0071] The control unit 43 may be a microcontroller unit (MCU), which connects the output terminal of the control signal to the control signal input terminal of the driving circuit, and provides a control signal with an appropriate level to each switch tube in the power-down retention switching circuit 3 .

[0072] In order to clearly illustrate the technical solutions of the embodiments of the present disclosure, eight specific embodiments are described in detail below.

[0073] Example 1

[0074] Figure 5 This is a circuit diagram of a switching power supply provided in the first embodiment of the present disclosure, as shown in FIG. Figure 5As shown, the switching power supply includes a PFC circuit, a tank circuit, a power-down hold switching circuit, a bus capacitor C1, and a detection and control module (not shown). The PFC circuit's input is connected to the power grid V1, and its output is connected to a load R1. The PFC circuit boosts the voltage at the input and outputs the voltage to the load R1 through the output to drive the load R1. The PFC circuit includes diodes D5-D8, a switch Q1, a freewheeling diode D1, and a first winding L1-1. Diodes D5-D8 form the PFC circuit's rectifier circuit, and the first winding L1-1 serves as the PFC circuit's boost inductor. The energy tank circuit includes a rectifier diode D3, a second energy storage capacitor C2, and at least one second winding L1-2. The second winding L1-2 and the first winding L1-1 form a first inductor L1. The second winding L1-2 serves as an auxiliary winding for the first inductor L1. After rectification, the second winding L1-2 serves as an energy source for the energy tank circuit. The energy storage capacitor C2 is used to store the energy generated by the second winding L1-2. The power-off retention switching circuit may include a second inductor L2, a switch Q2, a freewheeling diode D2, and a unidirectional conductive device D4, which may be a diode.

[0075] Diodes D1 and D2 can serve as freewheeling diodes for switching transistors, further reducing losses. Electrolytic capacitors can be used for busbar capacitor C1 and energy storage capacitor C2. Switching transistors Q1 and Q2 can be NMOS transistors.

[0076] The turns ratio of the second winding L1-2 of the first inductor L1 to the first winding L1-1 is less than or equal to 1, and one end of the second winding L1-2 is connected to the negative terminal of the busbar of the PFC circuit, and the other end is connected to the anode of the rectifier diode D3, and the cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2.

[0077] Diode D4 has two operating states: on and off. When the AC voltage is normally input, diode D4 is in the on state, allowing bus capacitor C1 and energy storage capacitor C2 to store energy simultaneously. When the AC voltage of the power grid drops, diode D4 is in the off state, and energy cannot flow from bus capacitor C1 to energy storage capacitor C2.

[0078] The bus capacitor C1 filters out AC components from the output of the PFC boost circuit and stores energy for the switching power supply; the energy storage capacitor C2 filters out high-frequency ripple components from the output of the auxiliary winding of the PFC boost circuit and stores energy for the switching power supply. The capacitance of the energy storage capacitor C2 is greater than that of the bus capacitor C1. For example, the capacitance of the energy storage capacitor C2 can be several times or even dozens of times that of the bus capacitor C1. Since the energy stored in the energy storage capacitor C2 needs to be fed back to the input of the power-off retention switching circuit when the input voltage drops, the larger the capacitance of the energy storage capacitor C2, the more energy it can store. When the input voltage drops, the more energy the energy storage capacitor C2 feeds back to the input of the power-off retention switching circuit, and the more stable the voltage output across the energy storage capacitor C2 can be.

[0079] The power-failure retention switching circuit operates as follows: When an input voltage drop is detected, or when the voltage of bus capacitor C1 drops to a preset threshold, the voltage of energy storage capacitor C2 flows through diode D4 to C1, replenishing the voltage. The input of the power-failure retention switching circuit is connected to energy storage capacitor C2, and the output of the power-failure retention switching circuit is connected to bus capacitor C1 and load R1. Energy storage capacitor C2 outputs a voltage to bus capacitor C1 and load R1 through the power-failure retention switching circuit, maintaining load power and forming a path for energy storage capacitor C2 to release energy to bus capacitor C1.

[0080] Specifically, when an input voltage drop is detected, the NMOS transistor Q2 and the freewheeling diode D2 are controlled to conduct, and the second inductor L2, the energy storage capacitor C2, and the NMOS transistor Q2 form a loop, releasing the electrical energy of the energy storage capacitor C2 to the bus capacitor C1, thereby maintaining a stable output voltage Vo across the bus capacitor C1. When the voltage Vo at the output end of the PFC circuit is detected to be lower than a predetermined voltage value, the NMOS transistor Q2 and the freewheeling diode D2 are controlled to conduct, and the second inductor L2, the energy storage capacitor C2, and the NMOS transistor Q2 form a loop, releasing the electrical energy of the energy storage capacitor C2 to the bus capacitor C1, thereby maintaining a stable output voltage Vo provided by the bus capacitor C1 to the backend.

[0081] When the energy storage capacitor C2 reaches its lowest point, the power-off hold switching circuit stops working, and the bus capacitor C1 loses its energy source and its voltage begins to drop. The voltage of the energy storage capacitor C2 drops to the load cutoff voltage, load R1 stops working, and the power-off hold switching circuit ends.

[0082] In related art, after a PFC circuit experiences an input power outage, the energy stored in bus capacitor C1 cannot be fully utilized to maintain the power-off period. However, in the disclosed embodiments, a storage capacitor C2 and associated circuitry are added to the switching power supply. During normal operation, the energy storage capacitor C2 stores energy when the AC input is normal. When the input voltage drops and the output voltage decreases, the energy storage capacitor C2 releases this energy to bus capacitor C1, providing the energy required to maintain a stable output voltage. This significantly extends the power-off holdover period.

[0083] In the embodiment of the present disclosure, the total capacitance of the energy storage capacitor C2 is reduced compared to the total capacitance in the related art. Taking a 54V output switching power supply as an example, in the related art, assuming that the capacity of the bus capacitor C1 is C, for the PFC circuit, the steady-state voltage after boosting V0 = 400V, the lowest voltage available to the subsequent load is V1 = 350V, then the electric energy available for power-off maintenance is W1 = 1 / 2*C*(400 2 -350 2 )=18750*C. After adopting the embodiment of the present disclosure, assuming that the capacitor storing electric energy is composed of C1 and C2, C2=4C1, and the discharge undervoltage point is 100V, then the energy storage capacitor C2 required to release the same electric energy W1=2*W1 / (400 2 -100 2 )=0.25*C, and the total capacitance of the capacitors C1+C2=0.3125*C. It can be seen from this that after adopting the embodiment of the present disclosure, only 31.25% of the capacitance of the related art is required to achieve the same power-off hold-up time, thereby reducing the volume of passive components and lowering costs.

[0084] Example 2

[0085] Figure 6 This is a circuit diagram of a switching power supply provided in the second embodiment of the present disclosure, as shown in FIG. Figure 6As shown, the switching power supply includes a PFC circuit, an energy storage circuit, a power-down retention switching circuit, a bus capacitor C1, and a detection and control module (not shown). The PFC circuit has an input connected to the power grid V1 and an output connected to a load R1. The PFC circuit is used to boost the voltage at the input and output the voltage to the load R1 through the output to drive the load R1. The PFC circuit includes diodes D5-D8, a switch Q1, a freewheeling diode D1, and a first winding L1-1. Diodes D5-D8 form the PFC circuit's rectifier circuit, and the first winding L1-1 serves as the PFC circuit's boost inductor. The energy storage circuit includes a rectifier diode D3, a second energy storage capacitor C2, and at least one second winding L1-2. The second winding L1-2 and the first winding L1-1 form the first inductor L1. After rectification, the second winding L1-2 serves as the energy source for the energy storage circuit. The energy storage capacitor C2 is used to store the energy generated by the second winding L1-2. The power-failure retention switching circuit in this scenario is a buck-boost circuit, which can include a second inductor L2, a switch Q2, and a freewheeling diode D2. The diodes in both the PFC circuit and the power-failure retention switching circuit can be replaced with switches to further reduce losses.

[0086] The turns ratio of the second winding L1-2 of the first inductor L1 to the first winding L1-1 is greater than 1, and one end of the second winding L1-2 is connected to the negative terminal of the busbar of the PFC circuit, and the other end is connected to the anode of the rectifier diode D3, and the cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2.

[0087] The bus capacitor C1 filters out the AC components of the output of the PFC boost circuit and stores energy for the switching power supply; the energy storage capacitor C2 filters out the high-frequency ripple components of the output of the auxiliary winding L1-2 of the PFC boost circuit and stores energy for the switching power supply.

[0088] The negative terminal of the energy storage capacitor C2 is connected to the negative terminal of the bus capacitor C1. When the AC voltage is normal, the PFC circuit operates normally, diode D3 is in the on state, and both the bus capacitor C1 and the energy storage capacitor C2 can store energy simultaneously. The voltage on the energy storage capacitor C2 is higher than that on the bus capacitor C1, resulting in a higher peak stored voltage and a greater amount of energy released during a power outage.

[0089] Electrolytic capacitors can be used for busbar capacitor C1 and energy storage capacitor C2. A higher voltage value can be selected for energy storage capacitor C2 to obtain a higher discharge voltage and reduce the capacitance of energy storage capacitor C2. Since the energy stored in energy storage capacitor C2 needs to be fed back to the input of the power-down hold switching circuit when the input voltage drops, the larger the capacitance of energy storage capacitor C2, the more energy it can store. When the input voltage drops, the more energy energy that energy storage capacitor C2 feeds back to the input of the power-down hold switching circuit, which can better maintain a stable voltage output across energy storage capacitor C2.

[0090] The working process of the power-off holding switching circuit is as follows: when the input voltage drop is detected, the energy storage capacitor C2 outputs voltage to the bus capacitor C1 and the load R1 through the power-off holding switching circuit to maintain the load power, forming a path for the energy storage capacitor C2 to release electrical energy to the bus capacitor C1.

[0091] Specifically, when an input voltage drop is detected, the power-off holding switching circuit is controlled to start working. When the capacitor voltage of the energy storage capacitor C2 is higher than the capacitor voltage of the bus capacitor C1, it works in the step-down mode, controls the working state of the NMOS tube Q2, and releases the electric energy of the energy storage capacitor C2 to the bus capacitor C1, so as to maintain the bus capacitor C1 to stably provide the output voltage to the back end.

[0092] When the energy storage capacitor C2 reaches its lowest point, the power-off hold switching circuit stops working, and the bus capacitor C1 loses its energy source and its voltage begins to drop. The voltage of the energy storage capacitor C2 drops to the load cutoff voltage, load R1 stops working, and the power-off hold switching circuit ends.

[0093] In related art, PFC circuits require a large bus capacitor C1 to provide energy to maintain the power-off period after an input power loss. However, in the disclosed embodiments, a storage capacitor C2 and related circuitry are added to the switching power supply. During normal operation, storage capacitor C2 stores energy when the AC input is normal. When the input voltage drops, storage capacitor C2 releases this energy to bus capacitor C1, providing the energy required to maintain a stable output voltage. This significantly extends the power-off hold-up period.

[0094] Example 3

[0095] Figure 7 This is a circuit diagram of a switching power supply provided in the third embodiment of the present disclosure, as shown in FIG. Figure 7As shown, the switching power supply includes a PFC circuit, an energy storage circuit, a power-off retention switching circuit, a bus capacitor C1, and a detection and control module (not shown). The PFC circuit has an input connected to the grid and an output connected to a load R1. The PFC circuit is used to boost the voltage at the input and output the voltage to the load R1 through the output to drive the load R1. The PFC circuit includes diodes D5-D8, a switch Q1, a freewheeling diode D1, and a first winding L1-1. Diodes D5-D8 form the rectifier circuit of the PFC circuit, and the first winding L1-1 serves as the boost inductor of the PFC circuit. The energy storage circuit includes a rectifier diode D3, a second energy storage capacitor C2, and at least one second winding L1-2. The second winding L1-2 and the first winding L1-1 form the first inductor L1. After rectification, the second winding L1-2 serves as the energy source for the energy storage circuit. The energy storage capacitor C2 is used to store the energy generated by the second winding L1-2. The power-down retention switching circuit in this scenario is a buck-boost circuit, including a second inductor L2 and switches Q2-Q5. Diode D1 in the PFC circuit can function as a freewheeling rectifier for the switches, further reducing losses.

[0096] The turns ratio of the second winding L1-2 of the first inductor L1 to the first winding L1-1 is greater than 1, and one end of the second winding L1-2 is connected to the negative terminal of the busbar of the PFC circuit, and the other end is connected to the anode of the rectifier diode D3, and the cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2.

[0097] The bus capacitor C1 filters out the AC components of the output of the PFC boost circuit and stores energy for the switching power supply; the energy storage capacitor C2 filters out the high-frequency ripple components of the output of the auxiliary winding L1-2 of the PFC boost circuit and stores energy for the switching power supply.

[0098] The negative terminal of the energy storage capacitor C2 is connected to the negative terminal of the bus capacitor C1. When the AC voltage is normal, the PFC circuit operates normally, diode D3 is in the on state, and both the bus capacitor C1 and the energy storage capacitor C2 can store energy simultaneously. The voltage on the energy storage capacitor C2 is higher than that on the bus capacitor C1, resulting in a higher peak stored voltage and a greater amount of energy released during a power outage.

[0099] Electrolytic capacitors can be used for the busbar capacitor C1 and the energy storage capacitor C2. The withstand voltage of the energy storage capacitor C2 can be set to a higher voltage value to obtain a higher discharge voltage and reduce the capacitance of the energy storage capacitor C2. Since the stored energy of the energy storage capacitor C2 needs to be fed back to the input of the power-down hold switching circuit when the input voltage drops, the larger the capacitance of the energy storage capacitor C2, the more energy it can store. When the input voltage drops, the more energy the energy storage capacitor C2 feeds back to the input of the power-down hold switching circuit, and the more stable the voltage output across the energy storage capacitor C2 can be.

[0100] The working process of the power-off holding switching circuit is as follows: when the input voltage drop is detected, and when the voltage of the bus capacitor C1 is detected to drop to a preset threshold, the input end of the power-off holding switching circuit is connected to the energy storage capacitor C2 of the energy storage circuit, and the output end of the power-off holding switching circuit is connected to the bus capacitor C1 and the load R1. The energy storage capacitor C2 outputs a voltage to the bus capacitor C1 and the load R1 through the power-off holding switching circuit to maintain the load power, forming a path for the storage capacitor C2 to release electrical energy to the bus capacitor C1.

[0101] Specifically, when an input voltage drop is detected, the power-off holding switching circuit, i.e., the buck-boost circuit, is controlled to start working. When the capacitor voltage of the energy storage capacitor C2 is higher than the capacitor voltage of the bus capacitor C1, the circuit operates in the buck mode. When the capacitor voltage of C2 is lower than the capacitor voltage of the bus capacitor C1, the circuit operates in the boost mode, controlling the working states of the NMOS tubes Q2-Q5 to release the electric energy of the energy storage capacitor C2 to the bus capacitor C1, so as to maintain the bus capacitor C1 to stably provide the output voltage to the back end. When it is detected that the voltage Vo at the output end of the PFC circuit is lower than a predetermined voltage value, the power-off holding switching circuit, i.e., the buck-boost circuit, is controlled to start operating. When the capacitor voltage of the energy storage capacitor C2 is higher than the capacitor voltage of the bus capacitor C1, the circuit operates in the buck mode. When the capacitor voltage of the energy storage capacitor C2 is lower than the capacitor voltage of the bus capacitor C1, the circuit operates in the boost mode, controlling the operating states of the NMOS transistors Q2-Q5 to release the electric energy of the energy storage capacitor C2 to the bus capacitor C1, thereby maintaining the bus capacitor C1 to provide a stable output voltage to the back end.

[0102] When the energy storage capacitor C2 reaches its lowest point, the power-off hold switching circuit stops working, and the bus capacitor C1 loses its energy source and its voltage begins to drop. The voltage of the energy storage capacitor C2 drops to the load cutoff voltage, load R1 stops working, and the power-off hold switching circuit ends.

[0103] In related art, PFC circuits require a large bus capacitor C1 to provide energy to maintain the power-off period after an input power loss. However, in the disclosed embodiments, a storage capacitor C2 and related circuitry are added to the switching power supply. During normal operation, storage capacitor C2 stores energy when the AC input is normal. When the input voltage drops and the output voltage decreases, storage capacitor C2 releases this energy to bus capacitor C1, providing the energy required to maintain a stable output voltage. This significantly extends the power-off hold-up period.

[0104] Example 4

[0105] Figure 8 This is a circuit diagram of a switching power supply provided in the fourth embodiment of the present disclosure, as shown in FIG. Figure 8As shown, the switching power supply includes a PFC circuit, an energy storage circuit, a power-off retention switching circuit, a bus capacitor C1, and a detection and control module (not shown). The PFC circuit has an input connected to the grid and an output connected to a load R1. The PFC circuit is used to boost the voltage at the input and output the voltage to the load R1 through the output to drive the load R1. The PFC circuit includes diodes D5-D8, a switch Q1, a freewheeling diode D1, and a first winding L1-1. Diodes D5-D8 form the rectifier circuit of the PFC circuit, and the first winding L1-1 serves as the boost inductor of the PFC circuit. The energy storage circuit includes a rectifier diode D3, a second energy storage capacitor C2, and at least one second winding L1-2. The second winding L1-2 and the first winding L1-1 form the first inductor L1. After rectification, the second winding L1-2 serves as the energy source for the energy storage circuit. The energy storage capacitor C2 is used to store the energy generated by the second winding L1-2. The power-down retention switching circuit in this scenario is a buck-boost circuit, including a second inductor L2 and switches Q2-Q5. Diode D1 in the PFC circuit can function as a freewheeling rectifier for the switches, further reducing losses.

[0106] One end of the second winding L1-2 of the first inductor L1 is connected to the bus positive terminal Vo of the PFC circuit, and the other end of L1-2 is connected to the anode of the rectifier diode D3. The cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2, and the negative electrode of C2 is connected to the positive electrode of the bus capacitor C1.

[0107] The bus capacitor C1 filters out the AC components of the output of the PFC boost circuit and stores energy for the switching power supply; the energy storage capacitor C2 filters out the high-frequency ripple components of the output of the auxiliary winding L1-2 of the PFC boost circuit and stores energy for the switching power supply.

[0108] The negative terminal of energy storage capacitor C2 is connected to the positive terminal of bus capacitor C1. When the AC voltage is normal, the PFC circuit operates normally, diode D3 is in the on state, and bus capacitor C1 and energy storage capacitor C2 can store energy simultaneously. The voltage on energy storage capacitor C2 is higher than that on bus capacitor C1, resulting in a higher peak stored voltage and a greater amount of energy released during a power outage.

[0109] Electrolytic capacitors can be used for the busbar capacitor C1 and the energy storage capacitor C2. The energy storage capacitor C2 and the busbar capacitor C1 are connected in series. The withstand voltage of the energy storage capacitor C2 can be selected to be a higher voltage value. To obtain a higher discharge voltage, the capacitance of the energy storage capacitor C2 is reduced. At this time, the energy storage capacitor C2 can be minimized. Since the electrical energy stored in the energy storage capacitor C2 needs to be fed back to the input end of the power-off retention switching circuit when the input voltage drops, the larger the capacitance of the energy storage capacitor C2, the more electrical energy it can store. When the input voltage drops, the energy storage capacitor C2 feeds back more electrical energy to the input end of the power-off retention switching circuit, and is more able to maintain a stable voltage output across the energy storage capacitor C2.

[0110] The working process of the power-off holding switching circuit is as follows: when it is detected that the voltage of the bus capacitor C1 drops to a preset threshold, the input end of the power-off holding switching circuit is connected to the energy storage capacitor C2 of the energy storage circuit, and the output end of the power-off holding switching circuit is connected to the bus capacitor C1 and the load R1. The energy storage capacitor C2 outputs a voltage to the bus capacitor C1 and the load R1 through the power-off holding switching circuit, which is used to maintain the load power, forming a path for the storage capacitor C2 to release electrical energy to the bus capacitor C1.

[0111] Specifically, when it is detected that the voltage Vo at the output end of the PFC circuit is lower than a predetermined voltage value, the power-off holding switching circuit, i.e., the buck-boost circuit, is controlled to start working. When the capacitor voltage of C2 is higher than the capacitor voltage of C1, it works in the buck mode; when the capacitor voltage of C2 is lower than the capacitor voltage of C1, it works in the boost mode, controls the working state of the NMOS tubes Q2-Q5, and releases the electric energy of the energy storage capacitor C2 to the bus capacitor C1, so as to maintain the bus capacitor C1 to stably provide the output voltage to the back end.

[0112] When the energy storage capacitor C2 reaches its lowest point, the power-off hold switching circuit stops working, and the bus capacitor C1 loses its energy source and its voltage begins to drop. The voltage of the energy storage capacitor C2 drops to the load cutoff voltage, load R1 stops working, and the power-off hold switching circuit ends.

[0113] In related art, PFC circuits require a large bus capacitor C1 to provide energy to maintain the power-off period after an input power outage. However, in the disclosed embodiments, a storage capacitor C2 and related circuitry are added to the switching power supply. During normal operation, storage capacitor C2 stores energy when the AC input is normal. When the output voltage drops, storage capacitor C2 releases this energy to bus capacitor C1, providing the energy required to maintain a stable output voltage. This significantly extends the power-off hold-up period.

[0114] Example 5

[0115] Figure 9 This is a circuit diagram of a switching power supply provided in the fifth embodiment of the present disclosure, as shown in FIG. Figure 9As shown, the switching power supply includes a PFC circuit, a tank circuit, a power-down hold switching circuit, a bus capacitor C1, and a detection and control module (not shown). The PFC circuit's input is connected to the grid, and its output is connected to a load R1. The PFC circuit is a totem pole bridgeless PFC circuit, which boosts the voltage at its input and outputs the voltage to the load R1 through its output to drive the load R1. The totem pole bridgeless PFC circuit includes switches Q4-Q5, switches Q1 and Q3, and a first winding L1-1. Switches Q4-Q5 form the PFC circuit's rectifier circuit, and the first winding L1-1 serves as the boost inductor of the totem pole bridgeless PFC circuit. The energy tank circuit includes a rectifier diode D3, a second energy storage capacitor C2, and at least one second winding L1-2. The second winding L1-2 and the first winding L1-1 form the first inductor L1. After rectification, the second winding L1-2 serves as the energy source for the energy tank circuit. The energy storage capacitor C2 is used to store the energy generated by the second winding L1-2. In this scenario, the power-failure retention switching circuit is a boost circuit, including the second inductor L2, the switch Q2, the diode D2, and the jumper diode D4.

[0116] The turns ratio of the second winding L1-2 of the first inductor L1 to the first winding L1-1 is less than or equal to 1, and one end of the second winding L1-2 is connected to the negative terminal of the busbar of the PFC circuit, and the other end is connected to the anode of the rectifier diode D3, and the cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2.

[0117] The jumper diode D4 has two operating states: on and off. When the AC voltage is normally input, diode D4 is in the on state, allowing the bus capacitor C1 and the energy storage capacitor C2 to store energy simultaneously. When the AC voltage of the power grid drops, diode D4 is in the off state, and energy cannot flow from the bus capacitor C1 to the energy storage capacitor C2.

[0118] The bus capacitor C1 filters out AC components from the output of the PFC boost circuit and stores energy for the switching power supply. The energy storage capacitor C2 filters out high-frequency ripple components from the output of the PFC boost circuit's auxiliary winding L1-2 and stores energy for the switching power supply. Electrolytic capacitors can be used for both bus capacitor C1 and energy storage capacitor C2. The capacitance of energy storage capacitor C2 is greater than that of bus capacitor C1. For example, the capacitance of energy storage capacitor C2 can be several or even dozens of times that of bus capacitor C1. Because the energy stored in energy storage capacitor C2 needs to be fed back to the input of the power-down hold switching circuit when the input voltage drops, the larger the capacitance of energy storage capacitor C2, the more energy it can store. When the input voltage drops, the more energy that energy storage capacitor C2 feeds back to the input of the power-down hold switching circuit, which helps maintain a stable voltage output across energy storage capacitor C2.

[0119] The power-off hold switching circuit operates as follows: When an input voltage drop is detected, the voltage of energy storage capacitor C2 flows through diode D4 to C1, replenishing the voltage. The input of the power-off hold switching circuit is connected to energy storage capacitor C2, and the output of the power-off hold switching circuit is connected to bus capacitor C1 and load R1. Energy storage capacitor C2 outputs a voltage to bus capacitor C1 and load R1 through the power-off hold switching circuit, maintaining load power and forming a path for energy storage capacitor C2 to release energy to bus capacitor C1. When the voltage Vo at the output of the PFC circuit is detected to be lower than a predetermined voltage value, NMOS transistor Q2 and freewheeling diode D2 are controlled to conduct, forming a loop with the second inductor L2, energy storage capacitor C2, and NMOS transistor Q2, releasing the energy from energy storage capacitor C2 to bus capacitor C1, thereby maintaining a stable output voltage Vo across bus capacitor C1.

[0120] When the energy storage capacitor C2 reaches its lowest point, the power-off hold switching circuit stops working, and the bus capacitor C1 loses its energy source and its voltage begins to drop. The voltage of the energy storage capacitor C2 drops to the load cutoff voltage, load R1 stops working, and the power-off hold switching circuit ends.

[0121] In related art, after a PFC circuit experiences a power outage, the energy stored in bus capacitor C1 cannot be fully utilized to maintain the power-off period. However, in the disclosed embodiments, a storage capacitor C2 and associated circuitry are added to the switching power supply. During normal operation of the switching power supply, storage capacitor C2 stores energy when the AC input is normal. When the input voltage drops, or when the voltage Vo at the PFC circuit output falls below a predetermined value, storage capacitor C2 releases this energy to bus capacitor C1, providing the energy required to maintain a stable output voltage. This significantly extends the power-off hold-up period.

[0122] Example 6

[0123] Figure 10 This is a circuit diagram of a switching power supply provided in Example 6 of the present disclosure, as shown in FIG. Figure 10As shown, the switching power supply includes a PFC circuit, a tank circuit, a power-down hold switching circuit, a bus capacitor C1, and a detection and control module (not shown). The PFC circuit's input is connected to the grid, and its output is connected to a load R1. The PFC circuit is a flying capacitor three-level totem pole bridgeless PFC circuit, configured to boost the voltage at its input and output voltage to load R1 through its output to drive the load R1. The flying capacitor three-level totem pole bridgeless PFC circuit includes switches Q7-Q8, switches Q1, Q3, Q4, and Q5, a capacitor C3, and a first winding L1-1. Switches Q7-Q8 form the rectifier circuit of the flying capacitor three-level totem pole bridgeless PFC circuit, and the first winding L1-1 serves as the boost inductor of the flying capacitor three-level totem pole bridgeless PFC circuit. The energy storage circuit includes a rectifier diode D3, a second energy storage capacitor C2, and at least one second winding L1-2. The second winding L1-2 and the first winding L1-1 form the first inductor L1. After rectification, the second winding L1-2 serves as the energy source for the energy storage circuit. The energy storage capacitor C2 is used to store the energy generated by the second winding L1-2. In this scenario, the power-off retention switching circuit is a boost circuit, including the second inductor L2, the switching transistor Q2, the diode D2, and the jumper diode D4. Diodes D2 and D4 in the power-off retention switching circuit can be replaced with switching transistors to further reduce losses.

[0124] The turns ratio of the second winding L1-2 of the first inductor L1 to the first winding L1-1 is less than or equal to 1, and one end of the second winding L1-2 is connected to the negative terminal of the busbar of the PFC circuit, and the other end is connected to the anode of the rectifier diode D3, and the cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2.

[0125] The jumper diode D4 has two operating states: on and off. When the AC voltage is normally input, diode D4 is in the on state, allowing the bus capacitor C1 and the energy storage capacitor C2 to store energy simultaneously. When the AC voltage of the power grid drops, diode D4 is in the off state, and energy cannot flow from the bus capacitor C1 to the energy storage capacitor C2.

[0126] The bus capacitor C1 filters out AC components from the output of the PFC boost circuit and stores energy for the switching power supply. The energy storage capacitor C2 filters out high-frequency ripple components from the output of the PFC boost circuit's auxiliary winding L1-2 and stores energy for the switching power supply. Electrolytic capacitors can be used for both bus capacitor C1 and energy storage capacitor C2. The capacitance of energy storage capacitor C2 is greater than that of bus capacitor C1. For example, the capacitance of energy storage capacitor C2 can be several or even dozens of times that of bus capacitor C1. Because the energy stored in energy storage capacitor C2 needs to be fed back to the input of the power-down hold switching circuit when the input voltage drops, the larger the capacitance of energy storage capacitor C2, the more energy it can store. When the input voltage drops, the more energy that energy storage capacitor C2 feeds back to the input of the power-down hold switching circuit, which helps maintain a stable voltage output across energy storage capacitor C2.

[0127] The power-failure retention switching circuit operates as follows: When an input voltage drop is detected, or when the voltage of bus capacitor C1 drops to a preset threshold, the voltage of energy storage capacitor C2 flows through diode D4 to C1, replenishing the voltage. The input of the power-failure retention switching circuit is connected to energy storage capacitor C2, and the output of the power-failure retention switching circuit is connected to bus capacitor C1 and load R1. Energy storage capacitor C2 outputs a voltage to bus capacitor C1 and load R1 through the power-failure retention switching circuit, which is used to maintain load power and form a path for energy storage capacitor C2 to release electrical energy to bus capacitor C1.

[0128] Specifically, when an input voltage drop is detected, or when a voltage Vo at the output end of the PFC circuit is detected to be lower than a predetermined voltage value, the NMOS transistor Q2 and the freewheeling diode D2 are controlled to be turned on, and the second inductor L2, the energy storage capacitor C2 and the NMOS transistor Q2 form a loop to release the electric energy of the energy storage capacitor C2 to the bus capacitor C1 to maintain a stable output voltage Vo across the bus capacitor C1.

[0129] When the energy storage capacitor C2 reaches its lowest point, the power-off hold switching circuit stops working, and the bus capacitor C1 loses its energy source and its voltage begins to drop. The voltage of the energy storage capacitor C2 drops to the load cutoff voltage, load R1 stops working, and the power-off hold switching circuit ends.

[0130] In related art, after a PFC circuit experiences an input power outage, the energy stored in bus capacitor C1 cannot be fully utilized to maintain the power-off period. However, in the disclosed embodiments, a storage capacitor C2 and associated circuitry are added to the switching power supply. During normal operation, the energy storage capacitor C2 stores energy when the AC input is normal. When the input voltage drops or the output voltage decreases, the energy storage capacitor C2 releases this energy to bus capacitor C1, providing the energy required to maintain a stable output voltage. This significantly extends the power-off holdover period.

[0131] Example 7

[0132] Figure 11 This is a circuit diagram of a switching power supply provided in the seventh embodiment of the present disclosure, as shown in FIG. Figure 11 As shown, the switching power supply includes a PFC circuit, a tank circuit, a power-down hold switching circuit, a bus capacitor C1, and a detection and control module (not shown). The PFC circuit's input is connected to the grid, and its output is connected to a load R1. The PFC circuit comprises two parallel totem-pole bridgeless PFC circuits, which boost the voltage at the input and output voltage to the load R1 through the output to drive the load R1. Furthermore, the PFC circuit includes switches Q7-Q8, switches Q1, Q3, Q4, and Q5, a third inductor L3, and a first winding L1-1. Switches Q7-Q8 form the PFC circuit's rectifier circuit, and the first winding L1-1 serves as the PFC circuit's boost inductor. One of the two parallel totem-pole bridgeless PFC circuits consists of switches Q1 and Q3 and the first winding L1-1, while the other consists of switches Q4 and Q5 and the third inductor L3. The energy storage circuit includes a rectifier diode D3, a second energy storage capacitor C2, and at least one second winding L1-2. The second winding L1-2 and the first winding L1-1 form the first inductor L1. After rectification, the second winding L1-2 serves as the energy source for the energy storage circuit. The energy storage capacitor C2 is used to store the energy generated by the second winding L1-2. In this scenario, the power-off retention switching circuit is a boost circuit, including the second inductor L2, the switching transistor Q2, the diode D2, and the jumper diode D4. Diodes D2 and D4 in the power-off retention switching circuit can be replaced with switching transistors to further reduce losses.

[0133] The turns ratio of the second winding L1-2 of the first inductor L1 to the first winding L1-1 is less than or equal to 1, and one end of the second winding L1-2 is connected to the negative terminal of the busbar of the PFC circuit, and the other end is connected to the anode of the rectifier diode D3, and the cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2.

[0134] The jumper diode D4 has two operating states: on and off. When the AC voltage is normally input, diode D4 is in the on state, allowing the bus capacitor C1 and the energy storage capacitor C2 to store energy simultaneously. When the AC voltage of the power grid drops, diode D4 is in the off state, and energy cannot flow from the bus capacitor C1 to the energy storage capacitor C2.

[0135] The bus capacitor C1 filters out AC components from the output of the PFC boost circuit and stores energy for the switching power supply. The energy storage capacitor C2 filters out high-frequency ripple components from the output of the PFC boost circuit's auxiliary winding L1-2 and stores energy for the switching power supply. Electrolytic capacitors can be used for both bus capacitor C1 and energy storage capacitor C2. The capacitance of energy storage capacitor C2 is greater than that of bus capacitor C1. For example, the capacitance of energy storage capacitor C2 can be several or even dozens of times that of bus capacitor C1. Because the energy stored in energy storage capacitor C2 needs to be fed back to the input of the power-down hold switching circuit when the input voltage drops, the larger the capacitance of energy storage capacitor C2, the more energy it can store. When the input voltage drops, the more energy that energy storage capacitor C2 feeds back to the input of the power-down hold switching circuit, which helps maintain a stable voltage output across energy storage capacitor C2.

[0136] The power-failure retention switching circuit operates as follows: When an input voltage drop is detected, or when the voltage of bus capacitor C1 drops to a preset threshold, the voltage of energy storage capacitor C2 flows through diode D4 to C1, replenishing the voltage. The input of the power-failure retention switching circuit is connected to energy storage capacitor C2, and the output of the power-failure retention switching circuit is connected to bus capacitor C1 and load R1. Energy storage capacitor C2 outputs a voltage to bus capacitor C1 and load R1 through the power-failure retention switching circuit, which is used to maintain load power and form a path for energy storage capacitor C2 to release electrical energy to bus capacitor C1.

[0137] Specifically, when an input voltage drop is detected, or when a voltage Vo at the output end of the PFC circuit is detected to be lower than a predetermined voltage value, the NMOS transistor Q2 and the freewheeling diode D2 are controlled to be turned on, and the second inductor L2, the energy storage capacitor C2 and the NMOS transistor Q2 form a loop to release the electric energy of the energy storage capacitor C2 to the bus capacitor C1 to maintain a stable output voltage Vo across the bus capacitor C1.

[0138] When the energy storage capacitor C2 reaches its lowest point, the power-off hold switching circuit stops working, and the bus capacitor C1 loses its energy source and its voltage begins to drop. The voltage of the energy storage capacitor C2 drops to the load cutoff voltage, load R1 stops working, and the power-off hold switching circuit ends.

[0139] In related art, after a PFC circuit experiences an input power outage, the energy stored in bus capacitor C1 cannot be fully utilized to maintain the power-off period. However, in the disclosed embodiments, a storage capacitor C2 and associated circuitry are added to the switching power supply. During normal operation, the energy storage capacitor C2 stores energy when the AC input is normal. When the input voltage drops or the output voltage decreases, the energy storage capacitor C2 releases this energy to bus capacitor C1, providing the energy required to maintain a stable output voltage. This significantly extends the power-off holdover period.

[0140] Example 8

[0141] Figure 12 This is a circuit diagram of a switching power supply provided in the eighth embodiment of the present disclosure, as shown in FIG. Figure 12 As shown, the switching power supply includes a PFC circuit, a tank circuit, a power-down hold switching circuit, a bus capacitor C1, and a detection and control module (not shown). The PFC circuit's input is connected to the grid, and its output is connected to a load R1. The PFC circuit comprises two parallel PFC circuits, which boost the voltage at the input and output voltage to the load R1 through the output to drive the load R1. The PFC circuit includes a first winding L1-1, diodes D5-D8, a switch Q1, a first winding L3-1, and a switch Q3. Diodes D5-D8 form the PFC circuit's rectifier circuit, while the first windings L1-1 and L3-1 serve as the PFC circuit's boost inductor. One of the two parallel PFC circuits consists of the switch Q1 and the first winding L1-1, while the other consists of the switch Q3 and the first winding L3-1. The energy tank circuit includes rectifier diodes D3 and D10, a second energy storage capacitor C2, a second winding L3-2, and a second winding L1-2. The energy tank circuit consists of two parallel paths: one path includes the second winding L3-2 and rectifier diode D10, and the other path includes the second winding L1-2 of the PFC inductor L1 and a rectifier diode D3. The second winding L1-2 and the first winding L1-1 form the first inductor L1, while the second winding L3-2 and the first winding L3-1 form the third inductor L3. The rectified energy from the second windings L1-2 and L3-2 serves as the energy source for the energy tank circuit. The energy storage capacitor C2 stores the energy generated by the second windings L1-2 and L3-2. In this scenario, the power-failure retention switching circuit is a boost circuit, comprising the second inductor L2, a switch Q2, a diode D2, and a jumper diode D4. Diodes D2 and D4 in the power-failure retention switching circuit can be replaced with switches to further reduce losses.

[0142] The turns ratio of the second winding L1-2 of the first inductor L1 to the first winding L1-1 is less than or equal to 1. One end of the second winding L1-2 is connected to the negative terminal of the PFC circuit busbar, and the other end is connected to the anode of the rectifier diode D3. The cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2. The turns ratio of the second winding L3-2 of the third inductor L3 to the first winding L3-1 is less than or equal to 1. One end of the second winding L3-2 is connected to the negative terminal of the PFC circuit busbar, and the other end is connected to the anode of the rectifier diode D3. The cathode of the rectifier diode D3 is connected to the positive electrode of the energy storage capacitor C2.

[0143] The jumper diode D4 has two operating states: on and off. When the AC voltage is normally input, diode D4 is in the on state, allowing the bus capacitor C1 and the energy storage capacitor C2 to store energy simultaneously. When the AC voltage of the power grid drops, diode D4 is in the off state, and energy cannot flow from the bus capacitor C1 to the energy storage capacitor C2.

[0144] The bus capacitor C1 filters out AC components from the output of the PFC boost circuit and stores energy for the switching power supply. The energy storage capacitor C2 filters out high-frequency ripple components from the output of the PFC boost circuit's auxiliary winding L1-2 and stores energy for the switching power supply. Electrolytic capacitors can be used for both bus capacitor C1 and energy storage capacitor C2. The capacitance of energy storage capacitor C2 is greater than that of bus capacitor C1. For example, the capacitance of energy storage capacitor C2 can be several or even dozens of times that of bus capacitor C1. Because the energy stored in energy storage capacitor C2 needs to be fed back to the input of the power-down hold switching circuit when the input voltage drops, the larger the capacitance of energy storage capacitor C2, the more energy it can store. When the input voltage drops, the more energy that energy storage capacitor C2 feeds back to the input of the power-down hold switching circuit, which helps maintain a stable voltage output across energy storage capacitor C2.

[0145] The power-down hold switching circuit operates as follows: When an input voltage drop is detected, the voltage on energy storage capacitor C2 flows through diode D4 to capacitor C1, replenishing the voltage. The input of the power-down hold switching circuit is connected to energy storage capacitor C2, while the output is connected to bus capacitor C1 and load R1. Energy storage capacitor C2 outputs a voltage to bus capacitor C1 and load R1 through the power-down hold switching circuit, maintaining load power and creating a path for energy storage capacitor C2 to release energy to bus capacitor C1.

[0146] Specifically, when an input voltage drop is detected, the NMOS tube Q2 and the freewheeling diode D2 are controlled to be turned on, and the second inductor L2, the energy storage capacitor C2 and the NMOS tube Q2 form a loop to release the electric energy of the energy storage capacitor C2 to the bus capacitor C1 to maintain a stable output voltage Vo across the bus capacitor C1.

[0147] When the energy storage capacitor C2 reaches its lowest point, the power-off hold switching circuit stops working, and the bus capacitor C1 loses its energy source and its voltage begins to drop. The voltage of the energy storage capacitor C2 drops to the load cutoff voltage, load R1 stops working, and the power-off hold switching circuit ends.

[0148] In related art, after a PFC circuit experiences an input power outage, the energy stored in bus capacitor C1 cannot be fully utilized to maintain the power-off period. However, in the disclosed embodiments, a storage capacitor C2 and associated circuitry are added to the switching power supply. During normal operation, the energy storage capacitor C2 stores energy when the AC input is normal. When the input voltage drops, the energy storage capacitor C2 releases this energy to bus capacitor C1, providing the energy required to maintain a stable output voltage. This significantly extends the power-off holdover period.

[0149] In a second aspect, an embodiment of the present disclosure further provides an electronic device, which includes the switching power supply as described above.

[0150] In some embodiments, the electronic device may further include a load, with the switching power supply providing DC power to the load. In this electronic device, the control unit may control the output of the power-off hold switching circuit to connect to the load. When the power grid is operating normally, the control unit connects the boost circuit to the load to provide power. When the power grid is operating abnormally, i.e., when a power outage occurs, the control unit may control the output of the power-off hold switching circuit to connect to the load to provide power, thereby ensuring that the load can operate temporarily without powering off.

[0151] Electronic devices can be used in high-power switching power supply output scenarios, extending the power-off hold-up time of the switching power supply without generating losses in the power circuit during normal operation. Electronic devices include, but are not limited to, computing devices such as servers and small computers; gateway devices or network devices such as base stations, routers, and switches; terminal devices such as laptops, desktops, tablets, and mobile phones; and energy devices such as photovoltaic equipment and smart charging stations.

[0152] Those skilled in the art will appreciate that all or some of the steps, systems, and functional modules / units in the apparatus disclosed above may be implemented as software, firmware, hardware, or a suitable combination thereof.

[0153] In hardware implementations, the division between functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation.

[0154] Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit (CPU), a digital signal processor, or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As is well known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, random access memory (RAM, more specifically SDRAM, DDR, etc.), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory (FLASH) or other disk storage; compact disc (CD-ROM), digital versatile disc (DVD) or other optical disc storage; magnetic cassettes, tapes, disk storage or other magnetic storage; any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, as is well known to those skilled in the art, communication media typically embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

[0155] The present disclosure has disclosed example embodiments, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly indicated, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

1. A switching power supply comprising: An energy storage circuit and a power factor correction (PFC) circuit, wherein the PFC circuit includes a first winding, and the energy storage circuit includes a second winding, an energy storage capacitor, and a rectifier element; The second winding and the first winding form a first inductor, the first winding is a main winding of the first inductor, the second winding is an auxiliary winding of the first inductor, and the second winding is used to obtain electrical energy from the first winding; The rectifier element is used to rectify the output current of the second winding; The energy storage capacitor is used to store the electric energy when the switching power supply is in a normal working state.

2. The switching power supply according to claim 1, wherein: It also includes a power-off holding switching circuit and a bus capacitor, wherein the power-off holding switching circuit is connected to the energy storage circuit and the bus capacitor respectively; the energy storage capacitor is also used to release electrical energy to the bus capacitor through the power-off holding switching circuit when the switching power supply is in an abnormal working state.

3. The switching power supply according to claim 2, wherein: The power-off holding switching circuit is one power-off holding switching circuit or at least two power-off holding switching circuits connected in parallel.

4. The switching power supply according to claim 2, wherein: It also includes a detection control module, which is used to detect the working state of the switching power supply. When the switching power supply is in an abnormal working state, the detection control module controls the power-off holding switching circuit to be turned on so that the energy storage capacitor releases electric energy to the bus capacitor through the power-off holding switching circuit.

5. The switching power supply according to claim 4, wherein: The switching power supply being in an abnormal working state includes: the input voltage of the PFC circuit dropping, and / or the bus voltage of the PFC circuit being less than a preset threshold.

6. The switching power supply according to claim 2, wherein: Two ends of the rectifier element are respectively connected to the first end of the second winding and the positive electrode of the energy storage capacitor; The second end of the second winding is connected to the negative terminal of the bus of the PFC circuit, the negative electrode of the bus capacitor, and the negative electrode of the energy storage capacitor; or the second end of the second winding is connected to the positive terminal of the bus of the PFC circuit and the positive electrode of the bus capacitor, and the negative electrode of the energy storage capacitor is connected to the negative terminal of the bus of the PFC circuit and the negative electrode of the bus capacitor; The input end of the power-off holding switching circuit is connected to the positive electrode of the energy storage capacitor, the output end of the power-off holding switching circuit is connected to the positive electrode of the bus capacitor, and the negative end of the power-off holding switching circuit is connected to the negative end of the bus of the PFC circuit.

7. The switching power supply according to claim 6, wherein: The second end of the second winding is connected to the negative end of the busbar of the PFC circuit, the turns ratio of the second winding to the first winding is less than or equal to 1, and the power-off holding switching circuit is a boost circuit or a buck-boost circuit.

8. The switching power supply according to claim 6, wherein: The second end of the second winding is connected to the negative end of the busbar of the PFC circuit, the turns ratio of the second winding to the first winding is greater than 1, and the power-off holding switching circuit is a step-down circuit or a step-up / step-down circuit.

9. The switching power supply according to claim 6, wherein: The second end of the second winding is connected to the positive end of the busbar of the PFC circuit, and the power-off holding switching circuit is a step-down circuit or a step-up / step-down circuit.

10. The switching power supply according to claim 4, wherein: The power-off holding switching circuit includes at least one switch tube, and the switch tube is used to control the power-off holding switching circuit to be turned on or off; The detection and control module includes an input voltage detection unit, an output voltage detection unit, and a control unit. The input voltage detection unit is connected to both ends of an AC source and is used to detect the input voltage of the PFC circuit. The AC source is connected to the input end of the PFC circuit. The output voltage detection unit is connected to the bus positive terminal and the bus negative terminal of the PFC circuit respectively, and is used to detect the bus voltage of the PFC circuit; The control unit is connected to at least one of the switch tubes and is used to control the switch tube to be turned on when the switching power supply is in an abnormal working state.

11. The switching power supply according to any one of claims 1 to 10, wherein: The PFC circuit is a single PFC circuit or at least two PFC circuits connected in parallel.

12. The switching power supply according to any one of claims 1 to 10, wherein: The energy storage circuit is one energy storage circuit or at least two energy storage circuits connected in parallel.

13. An electronic device comprising the switching power supply according to any one of claims 1 to 12.

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