Power supply circuit and switching power supply

Abstract

The invention discloses a power supply circuit and a switching power supply, and relates to the technical field of switching power supplies, the power supply circuit comprises a primary branch and multiple stages of secondary branches, and the multiple stages of secondary branches are sequentially coupled with the primary branch. The invention aims to reduce the hardware design cost of the switching power supply topology and reduce the occupied space of a circuit board.

Description

Technical Field

[0001] The present application relates to the technical field of switching power supplies, and in particular to a power supply circuit and a switching power supply. Background Art

[0002] In the topology of switching power supplies, there are generally single secondary branches and multiple secondary branches. When the number of branches in the multiple secondary branch structure is too large, the design of the transformer will be very complicated, the winding cost of the secondary winding will increase, and the coupling effect will deteriorate, which will affect the performance of the entire topology. The existing solution usually adopts the primary parallel solution, by introducing another primary winding and transformer to complete the output of multiple secondary branches. However, the primary parallel solution is equivalent to redesigning a circuit, requiring double the primary devices (such as primary switch tubes, RCD absorption circuits), which is costly and occupies a large space. Summary of the invention

[0003] The main purpose of this application is to provide a power supply circuit and a switching power supply, aiming to reduce the hardware design cost of the switching power supply topology and reduce the space occupied by the circuit board.

[0004] To achieve the above object, the present application proposes a power supply circuit, the power supply circuit comprising:

[0005] A primary branch and multiple secondary branches, wherein the multiple secondary branches are coupled to the primary branch in sequence.

[0006] In one embodiment, each secondary branch comprises a feedback winding, a parallel primary winding and a plurality of sub-secondary windings, wherein the parallel primary winding is arranged in parallel with the feedback winding;

[0007] The parallel primary winding serves as the primary winding of the next secondary branch, and is coupled to a plurality of sub-secondary windings in the next secondary winding;

[0008] The feedback winding and the plurality of sub-secondary windings are respectively coupled to the primary branch, or coupled to the parallel primary windings in the upper secondary branch.

[0009] In one embodiment, the same-name end of the feedback winding is electrically connected to the same-name end of the parallel primary winding of the same-level secondary branch, and the opposite-name end of the feedback winding is electrically connected to the opposite-name end of the parallel primary winding of the same-level secondary branch.

[0010] In one embodiment, the power supply circuit further includes:

[0011] A power input terminal, the power input terminal is used to connect to the power supply voltage;

[0012] A power switch is electrically connected to the power input terminal via the primary branch.

[0013] In one embodiment, the power supply circuit further includes:

[0014] A power supply control circuit, the power supply control circuit being electrically connected to at least one of the secondary branches;

[0015] The power control circuit is used to detect the voltage of the secondary branch and control the on or off time of the power switch according to the voltage of the secondary branch.

[0016] In one embodiment, the power control circuit includes:

[0017] Control chip;

[0018] A voltage feedback circuit, wherein a detection end of the voltage feedback circuit is electrically connected to at least one of the secondary branches; and a feedback end of the voltage feedback circuit is electrically connected to the control chip;

[0019] The voltage feedback circuit is used to detect the voltage of the secondary branch and output a corresponding voltage feedback signal to the control chip;

[0020] The control chip is used to receive the voltage feedback signal and control the power switch to be in an on / off state according to the voltage feedback signal.

[0021] In one embodiment, the power supply circuit further includes:

[0022] A protection circuit, wherein the protection circuit is electrically connected to the power input terminal and the power switch respectively;

[0023] The protection circuit is used to limit the power supply voltage connected to the power input terminal to a preset voltage range so as to protect the power switch.

[0024] In one embodiment, the protection circuit comprises:

[0025] A first resistor, a first capacitor and a clamping diode, wherein the first resistor and the first capacitor are connected in parallel, a first common connection end of the first resistor and the first capacitor is interconnected with the power input end and the opposite-name end of the primary branch, a second common connection end of the first resistor and the first capacitor is electrically connected to the cathode of the clamping diode, and an anode of the clamping diode is interconnected with the same-name end of the primary branch and the power switch.

[0026] In one embodiment, the power supply circuit further includes:

[0027] A plurality of rectifier circuits, each of which is electrically connected to the plurality of secondary branches; and is used to rectify the voltage of the secondary branch and then output it;

[0028] A plurality of output filter circuits, wherein the plurality of output filter circuits are electrically connected to the plurality of rectifier circuits in a one-to-one correspondence;

[0029] The output filter circuit is used to filter and output the rectified signal output by the rectifier circuit electrically connected to itself.

[0030] In one embodiment, the rectifier circuit includes a rectifier diode, and the output filter circuit includes a second capacitor; the anode of the rectifier diode is electrically connected to the same-name end of the feedback winding of the secondary branch or the same-name end of the sub-secondary winding of the secondary branch, and the first end of the second capacitor is electrically connected to the cathode of the rectifier diode; the second end of the second capacitor is electrically connected to the opposite-name end of the feedback winding of the secondary branch or the opposite-name end of the sub-secondary winding of the secondary branch.

[0031] The present application also provides a switching power supply, which includes any of the power supply circuits described above.

[0032] In one embodiment, the switching power supply includes at least one or more combinations of a forward switching power supply and a flyback switching power supply.

[0033] The present application proposes a power supply circuit, comprising a primary branch and multiple secondary branches, wherein the multiple secondary branches are coupled to the primary branch in sequence.

[0034] In practical applications, for topologies with multiple secondary branch structures, the multiple secondary branches can be coupled and connected with the primary branch in sequence, that is, each secondary branch can be used as the primary branch of the next secondary branch, and coupled and connected with the next secondary branch. For example, the primary branch is coupled and connected with the first secondary branch, and the first secondary branch is used as the primary branch of the second secondary branch, so that the second secondary branch is coupled and connected with the first secondary branch. In this way, for topologies with multiple secondary branch structures, it is not necessary to set up multiple primary devices, which reduces the circuit design cost and reduces the occupied space of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0036] Figure 1 A specific circuit diagram of an embodiment of the power supply circuit of the present application;

[0037] Figure 2A specific circuit diagram of another embodiment of the power supply circuit of the present application;

[0038] Figure 3 A schematic diagram of a circuit module of an embodiment of a power supply circuit of the present application;

[0039] Figure 4 A schematic diagram of a circuit module of another embodiment of the power supply circuit of the present application;

[0040] Figure 5 A schematic diagram of a circuit module of another embodiment of the power supply circuit of the present application;

[0041] Figure 6 A schematic diagram of a circuit module of another embodiment of the power supply circuit of the present application;

[0042] Figure 7 A specific circuit diagram of another embodiment of the power supply circuit of the present application;

[0043] Figure 8 A specific circuit diagram of an embodiment of a flyback switching power supply topology in the prior art;

[0044] Fig. 9 A specific circuit diagram of another embodiment of a flyback switching power supply topology in the prior art;

[0045] Fig.10 It is a specific circuit diagram of another embodiment of the flyback switching power supply topology in the prior art.

[0046] Description of Figure Numbers:

[0047] 10. Primary branch; 20. Secondary branch; 30. Power input terminal; 40. Power switch; 50. Power control circuit; 51. Voltage feedback circuit; 52. Control chip; 60. Protection circuit.

[0048] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0050] In addition, in this application, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0051] It can be understood that the working principle of the switching power supply is based on the switching action of the switching device (primary switch tube), controlling the energy storage and release of the inductor, and utilizing the coupling effect of the transformer to realize the transmission and conversion of energy. Therefore, the output voltage can be controlled by adjusting the on and off time of the primary switch tube. The flyback switching power supply and the forward switching power supply are two different switching power supply technologies, and their working principles and application scenarios are different. In the flyback switching power supply, when the switching device is turned on, the power supply voltage connected to the power input terminal 30 charges the primary coil of the transformer through the inductor, and stores energy in the inductor at the same time. When the switching device is turned off, the energy stored in the inductor is released through the secondary coil of the transformer to supply power to the load. In the forward switching power supply, when the switching device is turned on, the output transformer acts as a medium to directly couple the magnetic field energy, and the electrical energy and magnetic energy are converted into each other, so that the input and output are carried out simultaneously, that is, when the switching device is turned on, the current and energy flow into the load.

[0052] When the switching power supply topology includes only one secondary branch 20, the output voltage Vout is input into the control chip 52 as a feedback voltage to implement closed-loop control of the duty cycle of the switching device to achieve the purpose of adjusting the output voltage. Figure 8 As shown, its output voltage Vout is input into the control chip 52 as feedback voltage. The control chip 52 adjusts the PWM control signal according to the feedback voltage to control the on / off time of the switch tube Q, thereby adjusting the output voltage. When the topology of the flyback switching power supply includes multiple secondary branches 20, each secondary branch 20 can be connected to different loads to provide different voltage levels required to different parts of multiple different electronic devices or circuits at the same time. Each secondary branch 20 can have its own independent output voltage, which is determined by the turns ratio between the secondary windings of the transformer. Fig. 9As shown, its output voltage Vout 1 is used as the feedback voltage, the secondary branch 20 where Ns1 is located is the feedback winding, and the output voltages corresponding to other secondary branches 20 are determined by the turns ratio between each secondary winding of the transformer and the feedback winding, satisfying the following proportional relationship: Vout 1: Vout2: ...: Vout n = Ns1: Ns2: ...: Nsn, so that the output voltages of each channel can be controlled to meet the power supply requirements of loads with different voltage levels.

[0053] It should be noted that when the number of secondary branches 20 is too large (e.g., more than a dozen), the design of the transformer will be very complicated, the cost of winding the secondary winding will also increase, the coupling effect will deteriorate, and the performance of the entire switching power supply will be affected. The primary parallel connection solution in the prior art completes the output of multiple secondary branches 20 by introducing another primary winding and transformer, such as Fig.10 As shown. The existing primary parallel connection scheme is equivalent to redesigning a circuit, which requires double the primary devices (such as primary switch tubes Q1 and Q2, RCD absorption circuit). In addition, if the two primary switch tubes are controlled by one control chip 52, since the feedback winding is in the first circuit, the control accuracy of the output voltage corresponding to each secondary branch 20 of the second circuit is poor; if the two primary switch tubes are adjusted by two control chips 52 respectively, the circuit design cost is significantly increased, and since more components are required, the PCB layout area is increased.

[0054] To this end, the present application proposes a power supply circuit, which includes a primary branch 10 and multiple secondary branches 20 , wherein the multiple secondary branches 20 are coupled to the primary branch 10 in sequence.

[0055] refer to Figure 3 , the primary branch 10 is electrically connected to the power input terminal 30 for accessing the power supply voltage, and the multiple secondary branches 20 are coupled to the primary branch 10 in sequence, that is, each secondary branch 20 can be used as the primary branch 10 of the next secondary branch 20, and is coupled to the next secondary branch 20. For example, the primary branch 10 is coupled to the first secondary branch 20, and the first secondary branch 20 is used as the primary branch 10 of the second secondary branch 20, so that the second secondary branch 20 is coupled to the first secondary branch 20.

[0056] Optionally, each level of the secondary branch 20 includes a feedback winding, a parallel primary winding and a plurality of sub-secondary windings, and the parallel primary winding is arranged in parallel with the feedback winding;

[0057] The parallel primary winding serves as the primary winding of the next secondary branch 20, and is coupled to a plurality of sub-secondary windings in the next secondary winding;

[0058] The feedback winding and the plurality of sub-secondary windings are respectively coupled to the primary branch 10 , or coupled to the parallel primary windings in the upper secondary branch 20 .

[0059] Take the flyback switching power supply topology as an example for explanation. Figure 1 The topology includes a primary branch 10 and two secondary branches 20. The primary branch 10 includes a primary winding p1, whose corresponding number of turns is Np1. The two secondary branches 20 are respectively a first secondary branch 20 and a second secondary branch 20. The first secondary branch 20 includes a feedback winding s11, a parallel primary winding p2, and a plurality of sub-secondary windings s12, s13, ... s1n; the second secondary branch 20 includes a feedback winding s21, a parallel primary winding p3, and a plurality of sub-secondary windings s22, s23, ... s2n. In the first secondary branch 20, the parallel primary winding p2 is used as the primary winding of the second secondary branch 20, and is coupled to the plurality of sub-secondary windings in the second secondary branch 20. The feedback winding s21 and multiple sub-secondary windings s12, s13 ... s1n in the first secondary branch 20 are coupled to the primary winding p1 respectively. In the second secondary branch 20, its feedback winding s21 and multiple sub-secondary windings s22, s23 ... s2n are coupled to the parallel primary winding (p2 of the first secondary branch 20) in the previous secondary branch 20 (the first secondary branch 20).

[0060] Optionally, the same-name end of the feedback winding is electrically connected to the same-name end of the parallel primary winding of the same-level secondary branch 20, and the opposite-name end of the feedback winding is electrically connected to the opposite-name end of the parallel primary winding of the same-level secondary branch 20. Figure 1 For example, the same-name end of the feedback winding s11 in the first-level secondary branch 20 is electrically connected to the same-name end of the parallel primary winding p2 of the first-level secondary branch 20, and the opposite-name end of the feedback winding s11 is electrically connected to the opposite-name end of the parallel primary winding p2. Similarly, the same-name end of the feedback winding s21 in the second-level secondary branch 20 is electrically connected to the same-name end of the parallel primary winding p3 of the second-level secondary branch 20, and the opposite-name end of the feedback winding s21 is electrically connected to the opposite-name end of the parallel primary winding p3. The same-name end of the feedback winding sn1 in the n-th secondary branch 20 is electrically connected to the same-name end of the parallel primary winding pn+1 of the second-level secondary branch 20, and the opposite-name end of the feedback winding sn1 is electrically connected to the opposite-name end of the parallel primary winding pn+1. Thus, for the first-stage secondary branch 20, s11 is used as the feedback winding, and its output voltage Vout 11 is used as the feedback voltage. The output voltages corresponding to the other sub-secondary windings are determined by the turns ratio between the secondary windings of the transformer and the feedback winding, satisfying the following proportional relationship:

[0061] V out11 :Vout12 :V out13 :……:V out1n =N s11 :N s12 :N s13 :……:N s1n ;

[0062] For the second secondary branch 20, the parallel primary winding p2 of the first secondary branch 20 serves as the primary winding of the second secondary branch 20. Therefore, the output voltage corresponding to each sub-secondary winding of the second secondary branch 20 is determined by the turns ratio between each secondary winding of the transformer and the primary winding p2, satisfying the following proportional relationship: V out11 :V out21 :V out22 :……:V out2n =N p2 :N s21 :N s22 :……:N s2n .

[0063] From the above proportional relationship, it can be seen that only one control chip 52 and one switch tube Q are needed to realize the control of the output voltage of the multi-stage secondary branch 20. In practical applications, s11 can still be used as a feedback winding, and the control chip 52 detects the output voltage Vout 11 corresponding to the feedback winding and uses it as the feedback voltage. The duty cycle of the switch tube Q is controlled according to the feedback voltage. Since the number of turns of the feedback winding, the parallel primary winding and the multiple sub-secondary windings in each stage of the secondary branch 20 is fixed, the above proportional relationship can realize the control of multiple output voltages.

[0064] In practical applications, for a topology with multiple secondary branches 20, the parallel primary windings of each secondary branch 20 can be used as the primary windings of the next secondary branch 20, coupled with the feedback winding and multiple sub-secondary windings of the next secondary branch 20. In this way, there is no need to set up multiple primary components, which reduces the circuit design cost and the occupied space of the circuit board.

[0065] In one embodiment, reference Figure 3 , Figure 4 and Figure 7 , the power supply circuit further includes:

[0066] A power input terminal 30, wherein the power input terminal 30 is used to connect to a power supply voltage;

[0067] A power switch 40 , wherein the power switch 40 is electrically connected to the power input terminal 30 via the primary branch 10 .

[0068] A power control circuit 50, wherein the power control circuit 50 is electrically connected to at least one of the secondary branches 20;

[0069] The power control circuit 50 is used to detect the voltage of the secondary branch 20 and control the on or off time of the power switch 40 according to the voltage of the secondary branch 20 .

[0070] In this embodiment, the power switch 40 can be implemented by a switch tube such as a triode, a MOS tube, an IGBT tube, etc., or can be implemented by a switch device such as a relay, a contactor, a circuit breaker, etc. The power control circuit 50 can be implemented by a main controller, such as an MCU, a DSP (Digital Signal Process), an FPGA (Field Programmable Gate Array), a PLC, a SOC (System On Chip), etc.

[0071] Specifically, the power control circuit 50 is used to detect the voltage of the secondary branch 20, and control the power switch 40 to be in an on / off state according to the voltage of the secondary branch 20. Figure 1 The power control circuit 50 can detect the output voltage Vout 11 of the feedback winding s11, and output a corresponding PWM control signal according to the output voltage Vout 11 to adjust the duty cycle of the power switch 40Q, and control the time of the transformer storing and releasing energy by controlling the on or off time of the power switch 40, thereby realizing the adjustment of each output voltage.

[0072] Optionally, refer to Figure 5 , the power control circuit 50 comprises:

[0073] Control chip 52;

[0074] A voltage feedback circuit 51, wherein a detection end of the voltage feedback circuit 51 is electrically connected to at least one of the secondary branches 20; and a feedback end of the voltage feedback circuit 51 is electrically connected to the control chip 52;

[0075] The voltage feedback circuit 51 is used to detect the voltage of the secondary branch 20 and output a corresponding voltage feedback signal to the control chip 52;

[0076] The control chip 52 is used to receive the voltage feedback signal and control the power switch 40 to be in an on / off state according to the voltage feedback signal.

[0077] In this embodiment, the control chip 52 can be implemented by an MCU chip, a DSP chip, an FPGA chip, etc., and the voltage feedback circuit 51 can be implemented by a voltage divider circuit, a voltage detection chip, etc.

[0078] In combination with the above embodiment, when the parallel primary windings of each secondary branch 20 are used as the primary windings of the next secondary branch 20, and are coupled and connected with the feedback winding and multiple sub-secondary windings of the next secondary branch 20, the voltage feedback circuit 51 only needs to detect the output voltage corresponding to the feedback winding in the first secondary branch 20, and output the corresponding voltage feedback signal to the control chip 52, so that the control chip 52 adjusts the duty cycle of the power switch 40Q according to the voltage feedback signal, thereby controlling the time for the transformer to store and release energy. Since the sub-secondary windings, the feedback windings, and the parallel primary windings satisfy the above proportional relationship, the magnitude of the output voltage corresponding to each winding can be adjusted. It can be understood that the change in the duty cycle of the power switch 40 will affect the average value of the voltage output by the sub-secondary windings and the feedback winding of each secondary branch 20, and thus affect the voltage output to the load.

[0079] Specifically, the flyback switching power supply topology may include a multi-stage secondary branch 20, such as Figure 1 As shown, it includes a first-level secondary branch 20 and a second-level secondary branch 20. For the first-level secondary branch 20, s11 is used as a feedback winding, and its output voltage Vout 11 is used as a feedback voltage. The output voltages corresponding to other sub-secondary windings are determined by the turns ratio between each secondary winding of the transformer and the feedback winding, satisfying the following proportional relationship:

[0080] V out11 :V out12 :V out13 :……:V out1n =N s11 :N s12 :N s13 :……:N s1n ;

[0081] For the second secondary branch 20, the parallel primary winding p2 of the first secondary branch 20 serves as the primary winding of the second secondary branch 20. Therefore, the output voltage corresponding to each sub-secondary winding of the second secondary branch 20 is determined by the turns ratio between each secondary winding of the transformer and the primary winding p2, satisfying the following proportional relationship: V out11 :V out21 :V out22 :……:V out2n =N p2 :N s21 :N s22 :……:N s2n .

[0082] That is, the feedback winding is connected in parallel to serve as the primary winding of the next secondary branch 20, and the same-name end of the feedback winding is connected to the same-name end of the primary winding of the next secondary branch 20. The switch tube Q is the power switch 40. When the control chip 52 controls the switch tube Q to close, the voltage polarity of each secondary winding (including the feedback winding, the parallel primary winding and the sub-secondary winding) is opposite to the polarity of the power supply voltage Vin connected to the power input terminal 30. The diodes connected to each secondary winding (including D11, D12...D3n...) are all cut off, and the energy is stored in the air gap of the transformer. When the control chip 52 controls the switch tube Q to turn off, the transformer flux is reset, and the diodes connected to each secondary winding are all turned on. Each secondary winding releases energy to the load, satisfying the following proportional relationship: V out11 :V out21 :V out22 :……:V out2n =N p2 :N s21 :N s22 :……:N s2n , thereby controlling the output voltage of each channel to meet the different voltage requirements of the load.

[0083] Through the above-mentioned setting, it is only necessary to lead out the original feedback winding in the topology of the switching power supply in parallel as the primary winding of the next-level secondary branch 20 to achieve the same voltage control effect, with low cost, simple circuit structure and few components. In this way, the PCB board area is reduced and the power density of the circuit is improved.

[0084] In another embodiment, reference Figure 6 , the power supply circuit further includes:

[0085] A protection circuit 60, wherein the protection circuit 60 is electrically connected to the power input terminal 30 and the power switch 40 respectively;

[0086] The protection circuit 60 is used to limit the power voltage connected to the power input terminal 30 to a preset voltage range, so as to protect the power switch 40 .

[0087] Optionally, refer to Figure 2 , Figure 2For the flyback switching power supply topology of the present application, the protection circuit 60 (RCD clamping circuit) of the flyback switching power supply is composed of a first resistor R0, a first capacitor C0 and a clamping diode D0, wherein the first resistor R0 and the first capacitor C0 are connected in parallel, the first common connection end of the first resistor R0 and the first capacitor C0 is interconnected with the power input terminal 30 and the opposite end of the primary branch 10, the second common connection end of the first resistor R0 and the first capacitor C0 is electrically connected to the cathode of the clamping diode D0, and the anode of the clamping diode D0 is interconnected with the same end of the primary branch 10 and the power switch 40Q. Among them, the power input terminal 30 includes a first input terminal and a second input terminal, the first input terminal is interconnected with the first common connection end of the first resistor R0 and the first capacitor C0 and the opposite end of the primary branch 10, the second input terminal is electrically connected to the source of the MOS tube Q, and the drain of the MOS tube Q is electrically connected to the anode of the clamping diode D0. The MOS tube Q includes a parasitic capacitor C ds .

[0088] Specifically, when the switch tube Q is turned off, the energy cannot be transferred to the secondary side of the transformer and can only be transferred through the parasitic capacitor C ds The first resistor R0, the first capacitor C0 and the clamping diode D0 form a protection circuit 60, that is, an energy absorption loop, to absorb this energy. Since the capacitance of the first capacitor C0 is much larger than the parasitic capacitor C ds , the first capacitor C0 can absorb more energy. Since the voltage of the capacitor will not change suddenly, especially the voltage of the capacitor with large capacitance changes more slowly, the first capacitor C0 effectively reduces the voltage spike and change rate on the switch tube Q, and improves the electromagnetic interference (EMI) phenomenon of the switching power supply. When the current in the transformer winding flows in the reverse direction, the clamping diode D0 is cut off, the first capacitor C0 stops charging, and starts to discharge through the first resistor R0, thereby consuming the previously absorbed energy.

[0089] The setting of the protection circuit 60 reduces the voltage stress of the power switch 40 and the electromagnetic interference of the power circuit. By adjusting the values ​​of the components of the protection circuit 60, the working efficiency and stability of the switching power supply can be improved while ensuring the normal operation of the power circuit.

[0090] In another embodiment, reference Figure 1 to Figure 2 , the power supply circuit further includes:

[0091] A plurality of rectifier circuits, each of which is electrically connected to the plurality of secondary branches 20; and is used to rectify the voltage of the secondary branch 20 and then output it;

[0092] A plurality of output filter circuits, wherein the plurality of output filter circuits are electrically connected to the plurality of rectifier circuits in a one-to-one correspondence;

[0093] The output filter circuit is used to filter and output the rectified signal output by the rectifier circuit electrically connected to itself.

[0094] Optionally, the rectifier circuit includes a rectifier diode, and the output filter circuit includes a second capacitor; the anode of the rectifier diode is electrically connected to the same-name end of the feedback winding of the secondary branch 20 or the same-name end of the sub-secondary winding of the secondary branch 20, and the first end of the second capacitor is electrically connected to the cathode of the rectifier diode; the second end of the second capacitor is electrically connected to the opposite-name end of the feedback winding of the secondary branch 20 or the opposite-name end of the sub-secondary winding of the secondary branch 20.

[0095] like Figure 1 As shown, the flyback switching power supply topology includes a primary branch 10 and two secondary branches 20 (a first secondary branch 20 and a second secondary branch 20), the first secondary branch 20 includes a feedback winding s11, a plurality of rectifier diodes (D11, D12 ... D1n), a plurality of output filter circuits (C11, C12 ... C1n), a parallel primary winding p2, and a plurality of sub-secondary windings s12, s13 ... s1n; wherein, the anode of the rectifier diode D11 is electrically connected to the same-name end of the feedback winding s11 of the first secondary branch 20, the first end of the second capacitor C11 is electrically connected to the cathode of the rectifier diode D11; the second end of the second capacitor C11 is electrically connected to the opposite-name end of the feedback winding s11. The anode of the rectifier diode D12 is electrically connected to the same-name end of the sub-secondary winding s12 of the first secondary branch 20, and the first end of the second capacitor C12 is electrically connected to the cathode of the rectifier diode D12; the second end of the second capacitor C12 is electrically connected to the opposite-name end of the sub-secondary winding s12. The second-level secondary branch 20 includes a feedback winding s21, a plurality of rectifier diodes (D21, D22...D2n), a plurality of output filter circuits (C21, C22...C2n), a parallel primary winding p3, and a plurality of sub-secondary windings s22, s23...s2n; wherein, the anode of the rectifier diode D21 is electrically connected to the same-name end of the feedback winding s21 of the second secondary branch 20, and the first end of the second capacitor C21 is electrically connected to the cathode of the rectifier diode D21; the second end of the second capacitor C21 is electrically connected to the opposite-name end of the feedback winding s21. The anode of the rectifier diode D22 is electrically connected to the same-name end of the sub-secondary winding s22 of the second secondary branch 20, the first end of the second capacitor C22 is electrically connected to the cathode of the rectifier diode D22; the second end of the second capacitor C22 is electrically connected to the opposite-name end of the sub-secondary winding s22.

[0096] Specifically, when the switch tube Q is turned on, the voltage polarity of each secondary winding (including the feedback winding, the parallel primary winding and the sub-secondary winding) is opposite to the polarity of the power supply voltage Vin connected to the power input terminal 30, and the rectifier diodes (including D11, D12...D3n...) are all cut off, and the energy is stored in the air gap of the transformer, that is, the energy is stored in the primary winding. When the switch tube Q is turned off, the transformer flux is reset, and each rectifier diode is turned on. The energy stored in the primary winding of the transformer passes through the secondary winding, and is rectified by the rectifier diode, and filtered by the second capacitor and then output to the corresponding load. That is, the rectifier diode rectifies the voltage on the corresponding secondary winding into direct current. The rectified voltage is then filtered by the second capacitor to increase the DC level to ensure that the voltage requirement of the load is met.

[0097] The rectifier circuit can convert the released AC voltage into a DC voltage to power the load. The output filter circuit further smoothes the rectified DC voltage, reduces the ripple component in the output voltage, and improves the purity of the DC voltage to provide a more stable DC power supply to the load, thereby reducing the impact on the load. The rectifier circuit and the output filter circuit work together to enable the flyback switching power supply to provide a stable DC power supply to meet the needs of different loads.

[0098] The present application provides a switching power supply, which includes any of the power supply circuits described above.

[0099] Optionally, the switching power supply includes at least one or more combinations of a forward switching power supply and a flyback switching power supply.

[0100] It is worth noting that, since the switching power supply of the present application includes the above-mentioned power supply circuit, the embodiments of the switching power supply of the present application include all technical solutions of all embodiments of the above-mentioned power supply circuit, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0101] The above description is only an optional embodiment of the present application, and does not limit the patent scope of the present application. All equivalent structural changes made by using the contents of the present application specification and drawings under the inventive concept of the present application, or directly / indirectly used in other related technical fields are included in the scope of the present application.

Claims

1. A power supply circuit, characterized in that: The power supply circuit comprises: A primary branch and multiple secondary branches, wherein the multiple secondary branches are coupled to the primary branch in sequence.

2. The power supply circuit according to claim 1, characterized in that Each level of the secondary branch includes a feedback winding, a parallel primary winding and a plurality of sub-secondary windings, wherein the parallel primary winding is arranged in parallel with the feedback winding; The parallel primary winding serves as the primary winding of the next secondary branch, and is coupled to a plurality of sub-secondary windings in the next secondary winding; The feedback winding and the plurality of sub-secondary windings are respectively coupled to the primary branch, or coupled to the parallel primary windings in the upper secondary branch.

3. The power supply circuit according to claim 2, characterized in that: The same-name end of the feedback winding is electrically connected to the same-name end of the parallel primary winding of the same-level secondary branch, and the opposite-name end of the feedback winding is electrically connected to the opposite-name end of the parallel primary winding of the same-level secondary branch.

4. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes: A power input terminal, the power input terminal is used to connect to the power supply voltage; A power switch is electrically connected to the power input terminal via the primary branch.

5. The power supply circuit according to claim 4, characterized in that: The power supply circuit also includes: A power supply control circuit, the power supply control circuit being electrically connected to at least one of the secondary branches; The power control circuit is used to detect the voltage of the secondary branch and control the on or off time of the power switch according to the voltage of the secondary branch.

6. The power supply circuit according to claim 5, characterized in that: The power control circuit comprises: Control chip; A voltage feedback circuit, wherein a detection end of the voltage feedback circuit is electrically connected to at least one of the secondary branches; and a feedback end of the voltage feedback circuit is electrically connected to the control chip; The voltage feedback circuit is used to detect the voltage of the secondary branch and output a corresponding voltage feedback signal to the control chip; The control chip is used to receive the voltage feedback signal and control the power switch to be in an on / off state according to the voltage feedback signal.

7. The power supply circuit according to claim 4, characterized in that: The power supply circuit also includes: A protection circuit, wherein the protection circuit is electrically connected to the power input terminal and the power switch respectively; The protection circuit is used to limit the power supply voltage connected to the power input terminal to a preset voltage range so as to protect the power switch.

8. The power supply circuit according to claim 7, characterized in that: The protection circuit comprises: A first resistor, a first capacitor and a clamping diode, wherein the first resistor and the first capacitor are connected in parallel, a first common connection end of the first resistor and the first capacitor is interconnected with the power input end and the opposite-name end of the primary branch, a second common connection end of the first resistor and the first capacitor is electrically connected to the cathode of the clamping diode, and an anode of the clamping diode is interconnected with the same-name end of the primary branch and the power switch.

9. The power supply circuit according to claim 1, characterized in that: The power supply circuit also includes: A plurality of rectifier circuits, each of which is electrically connected to the plurality of secondary branches; and is used to rectify the voltage of the secondary branch and then output it; A plurality of output filter circuits, wherein the plurality of output filter circuits are electrically connected to the plurality of rectifier circuits in a one-to-one correspondence; The output filter circuit is used to filter and output the rectified signal output by the rectifier circuit electrically connected to itself.

10. The power supply circuit according to claim 9, characterized in that: The rectifier circuit includes a rectifier diode, and the output filter circuit includes a second capacitor; the anode of the rectifier diode is electrically connected to the same-name end of the feedback winding of the secondary branch or the same-name end of the sub-secondary winding of the secondary branch, and the first end of the second capacitor is electrically connected to the cathode of the rectifier diode; the second end of the second capacitor is electrically connected to the opposite-name end of the feedback winding of the secondary branch or the opposite-name end of the sub-secondary winding of the secondary branch.

11. A switching power supply, characterized in that: The switching power supply comprises the power supply circuit according to any one of claims 1 to 10.

12. The switching power supply according to claim 11, characterized in that: The switching power supply includes at least one or more combinations of a forward switching power supply and a flyback switching power supply.

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