Switching power supply circuit with multiple isolated outputs

Abstract

The present application provides a switching power supply circuit with multiple isolated outputs, comprising a chopper input control circuit, an isolated power transmission circuit, a rectifier output circuit and an isolated feedback circuit. According to embodiments of the present application, the isolated power transmission circuit is used, so that an input circuit and an output circuit can realize reinforced insulation, and multiple outputs are isolated, so that a user can safely use an external device. Moreover, the isolated feedback circuit performs weighted processing on multiple voltage feedback signals of the rectifier output circuit, optimizing the cross regulation rate between multiple rectified outputs, and ensuring that each rectified output has higher stability and power application range; and the voltage feedback signals are transmitted to the chopper input control circuit by means of multi-level isolation, so that the problem where a single-stage isolated optocoupler fails to meet the safety distance requirements for ultra-high voltage input is solved.

Description

A switching power supply circuit with multi-channel isolated output Technical Field

[0001] The present application relates to the field of circuit technology, and in particular to a switching power supply circuit with multi-channel isolated outputs. Background Art

[0002] Current charging station systems, energy storage systems, and photovoltaic systems often require multiple auxiliary power supplies. As voltage levels in these systems increase, the requirements for auxiliary power supply input voltage levels are also increasing, gradually moving towards 1500V DC. Furthermore, the diverse load scenarios in each system place higher demands on the auxiliary power supply's rated power, instantaneous overload power, isolation level, adjustable output voltage, and multiple outputs.

[0003] In most systems, the auxiliary power supply's load includes devices that may come into direct electrical contact with the user, such as displays and control interfaces. Therefore, reinforced insulation between the primary and secondary sides of the auxiliary power supply is essential to ensure user safety. Currently, the creepage distance of commonly used optocouplers (isolated optocouplers) is approximately 8mm. However, when voltage levels reach 1500V or higher, the creepage distance requirement for reinforced insulation between the primary and secondary sides increases to 15mm or even higher (creepage distance increases with voltage level). A single isolated optocoupler cannot meet such high creepage distance requirements. While isolated optocouplers with greater safety distances can be used, they are subject to further limitations in terms of cost, size, and procurement risk. Furthermore, if voltage levels continue to increase, for example, to 2000V or higher, it will be difficult to find isolated optocouplers that meet such high safety distance requirements on the market.

[0004] To address the isolation control issue between multiple outputs, the commonly used solution currently is single-channel feedback control. The voltages of the other channels are controlled by a low-dropout linear regulator (LDO) to ensure that the output voltages of the other channels remain stable within the set voltage range even when the loads on each channel are uneven. However, this solution can only be applied to low-power solutions. Otherwise, the LDO's high power consumption will complicate the module's thermal design. Alternatively, an additional feedback control circuit can be added to the non-feedback output channel to ensure output voltage stability. However, this solution greatly increases the complexity of the design and also significantly increases losses and costs. Technical issues

[0005] The main purpose of this application is to provide a switching power supply circuit with multi-channel isolated outputs, aiming to solve the problems in the related art of multi-channel isolated output switching power supply circuits in scenarios with ultra-wide input voltage ranges, poor cross-regulation rate using single-channel control, high complexity of multi-channel feedback control, and inability to meet safety distance requirements using single-stage isolation optocouplers. Technical Solutions

[0006] To achieve the above-mentioned objectives, the present application provides a switching power supply circuit with multiple isolated outputs, comprising: a chopping input control circuit, an isolated power transmission circuit, a rectifier output circuit and an isolated feedback circuit; the isolated power transmission circuit and the isolated feedback circuit are respectively connected to the chopping input control circuit and the rectifier output circuit, the chopping input control circuit includes a switch tube, and the switch tube is electrically connected to the isolated power transmission circuit; the isolated power transmission circuit is used to isolate and transmit the pulsating voltage input by the chopping input control circuit to the rectifier output circuit; the rectifier output circuit is used to rectify the pulsating voltage output by the isolated power transmission circuit to obtain a DC voltage, and output multiple DC voltages to an external load; the isolated feedback circuit is used to perform multi-level isolation on the collected voltage feedback signal corresponding to the rectifier output circuit and transmit it to the chopping input control circuit; the chopping input control circuit is used to control the on-off state of the switch tube according to the voltage feedback signal to adjust the DC voltage to a preset voltage index. Beneficial effects

[0007] From the above description, it can be seen that the present application achieves enhanced insulation between the input circuit and the output circuit through an isolated power transmission circuit to ensure that users can safely use external equipment, and performs weighted processing on multiple voltage feedback signals of the rectifier output circuit through an isolated feedback circuit, thereby optimizing the cross-regulation rate between multiple rectifier outputs and ensuring that each rectifier output has higher stability and power applicability range; and transmits the voltage feedback signal to the chopper input control circuit through multi-stage isolation, thereby solving the problem that the use of a single-stage isolation optocoupler cannot meet the safety distance requirements of ultra-high voltage input. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0009] FIG1 is a schematic structural diagram of a switching power supply circuit with multiple isolated outputs according to an embodiment of the present application;

[0010] FIG2 is a circuit schematic diagram of a switching power supply circuit with multiple isolated outputs according to an embodiment of the present application;

[0011] FIG3 is a circuit schematic diagram of a two-stage multi-path isolation feedback circuit according to an embodiment of the present application;

[0012] FIG4 is a circuit schematic diagram of a multi-stage multi-path isolation feedback circuit according to an embodiment of the present application;

[0013] FIG5 is a circuit schematic diagram of another multi-stage multi-path isolation feedback circuit according to an embodiment of the present application. Modes for Carrying Out the Invention

[0014] In order to make the purpose, features, and advantages of the invention of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0015] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of this application, the meaning of "plurality" is two or more, unless otherwise clearly specified.

[0016] In the related art, the switching power supply adopts a single-channel control feedback, which is complex and cannot meet the safety distance requirements using a single isolation optocoupler. Therefore, the embodiment of the present application provides a switching power supply circuit with multiple isolated outputs.

[0017] As shown in FIG1 , an embodiment of the present application provides a structural schematic diagram of a multi-channel isolated output switching power supply circuit, which includes: a chopping input control circuit 100, an isolated power transmission circuit 200, a rectifier output circuit 300, and an isolated feedback circuit 400; the isolated power transmission circuit 100 and the isolated feedback circuit 400 are respectively connected to the chopping input control circuit 100 and the rectifier output circuit 300, the chopping input control circuit includes a switch tube, and the switch tube is electrically connected to the isolated power transmission circuit; the isolated power transmission circuit 200 00, used to isolate the pulsating voltage input by the chopping input control circuit and transmit it to the rectifier output circuit; the rectifier output circuit 300, used to rectify the pulsating voltage output by the isolation power transmission circuit to obtain a DC voltage, and output multiple DC voltages to an external load; the isolation feedback circuit 400, used to perform multi-level isolation on the collected voltage feedback signal corresponding to the rectifier output circuit and transmit it to the chopping input control circuit; the chopping input control circuit 100, used to control the on-off state of the switch tube according to the voltage feedback signal to adjust the DC voltage to a preset voltage index.

[0018] Specifically, the multi-channel isolated output switching power supply in this embodiment achieves reinforced insulation between the input circuit and the output circuit through an isolated power transmission circuit to ensure that users can safely use external devices, and performs weighted processing on multiple voltage feedback signals of the rectifier output circuit through an isolated feedback circuit, thereby optimizing the cross-regulation rate between the multiple rectifier outputs and ensuring that each rectifier output has higher stability and power applicability range; and transmits the voltage feedback signal to the chopper input control circuit through multi-stage isolation, solving the problem that the use of a single-stage isolated optocoupler cannot meet the safety distance requirements of ultra-high voltage input.

[0019] FIG2 is a schematic diagram of a switching power supply circuit with multiple isolated outputs according to this embodiment. Referring to FIG2 , the chopping input control circuit 100 includes a controller (not shown) and an input chopping circuit. The controller is electrically connected to the input chopping circuit and the isolated feedback circuit. The input chopping circuit includes multiple flyback circuits connected in series, with the first flyback circuit connected to the positive terminal of the power supply and the last flyback circuit connected to the negative terminal of the power supply.

[0020] Specifically, the isolated power transmission circuit 200 includes a transformer T20, and taking the first flyback circuit as an example, the flyback circuit includes a first capacitor C101 and a switch tube Q101, one end of the first capacitor C101 is connected to the first end of the first winding N201 of the transformer T20, and the other end is connected to the first end of the switch tube Q101; the second end of the switch tube Q101 is connected to the controller, and the third end is connected to the second end of the first winding N201; the controller is used to: calculate the duty cycle of the drive signal based on the voltage feedback signal and the input current sampling signal, and output the corresponding drive signal according to the duty cycle to control the on and off of the switch tube, thereby adjusting the pulsating voltage. Among them, the first capacitors C101, C102, C103, and C104 are bus capacitors, which are used for energy storage and buffering under high input voltage conditions. Electrolytic capacitors with conventional voltage resistance levels can be used as bus capacitors; the switching tubes Q101, Q102, Q103, and Q104 are the main switching tubes of each flyback circuit; and the windings N201, N202, N203, and N204 are the primary windings of the transformer T20.

[0021] In this embodiment, the switching power supply can meet the power input of an ultra-wide voltage range, for example, a pulsating voltage range of 200 to 1500V, wherein the power input Vin can be a DC power or a DC power obtained by rectifying an AC power. Based on the consideration of the wide range of input pulsating voltage, the primary main circuit in the chopper input control circuit 100 adopts a multi-channel series flyback circuit to facilitate the realization of the 1500V DC voltage or higher level voltage input requirement through commonly used switching tubes such as MOS tubes; by controlling the on and off of the switch of the primary main circuit, the energy of the input side pulsating voltage Vin is stored in the isolated power transmission circuit; it should be noted that considering that most load usage scenarios of this type of switching power supply are SELV circuits (safety extra-low voltage circuits), reinforced insulation is required between the output circuit and the input circuit. Therefore, this embodiment uses a transformer as the isolated power transmission circuit 200, and the turns ratio of the transformer can be adjusted according to the actual input and output voltage range and power supply power. The main function of the transformer is to store the energy of the primary input source and transmit it to the secondary rectifier output circuit after magnetic isolation. Rectifier output circuit 300 rectifies the pulsating voltage, employing diodes or other rectification topologies such as synchronous rectification, depending on the actual circuit topology and requirements. Isolation feedback circuit 400 transmits the multi-channel isolated voltage feedback signals output by rectifier output circuit 300 to chopper input control circuit 100 through multi-stage isolation and weighted feedback.

[0022] The isolated power transmission circuit 200 in this embodiment includes a transformer T20, whose main function is to store energy from the primary input source and transmit it to the secondary rectifier output circuit after magnetic isolation. The controller calculates the duty cycle of the drive signal based on the current sampling signal of the primary side and the voltage feedback signal of the secondary side, and outputs a drive signal with a corresponding duty cycle to drive the switch tube to turn on and off, thereby achieving precise control of the output voltage and output power. Specifically, when the primary side main switches Q101, Q102, Q103, and Q104 are turned on, the input power charges the main transformer T20. When the primary side main switches Q101, Q102, Q103, and Q104 are turned off, the energy stored in the main transformer T20 is released on the secondary side, and the secondary side rectifier circuit rectifies the pulsating energy to a specified value. Depending on the input and output voltage and power size, the primary side main circuit can operate in continuous mode or discontinuous mode.

[0023] Furthermore, the rectifier output circuit includes any one of the following: a single-channel rectifier output circuit, a multi-channel isolated rectifier output circuit; taking the multi-channel isolated rectifier output circuit as an example, please refer to Figure 2, the multi-channel isolated rectifier output circuit includes multiple sub-rectifier output modules, taking the first sub-rectifier output module as an example, the sub-rectifier output module includes a diode D301 and a second capacitor C301, the positive pole of the diode D301 is connected to the first end of the second winding N211 of the transformer T20, the negative pole is connected to the isolated feedback circuit 400, and the second end of the second winding N211 is grounded; one end of the second capacitor C301 is connected to the negative pole of the diode D301, and the other end is connected to the second end of the second winding N211; wherein, the second windings N211 and N212 are the secondary windings of the transformer T20.

[0024] Specifically, the rectifier output circuit in this embodiment rectifies and outputs the pulsating voltage output by the transformer through the diode D301, the second capacitor C301 and the transformer winding N211; at the same time, since the sub-rectifier output modules are isolated by the transformer, the output of each sub-rectifier module is also an isolated output to meet the isolation requirements of different loads for the power supply.

[0025] Furthermore, as shown in Figure 3, a circuit schematic diagram of a two-stage multi-channel isolation feedback circuit provided in this embodiment is shown in Figure 4. A circuit schematic diagram of a multi-stage multi-channel isolation feedback circuit provided in this embodiment is shown in Figures 3 and 4. The isolation feedback circuit 400 includes multiple sub-isolation feedback circuits (Unit 401, Unit 411, Unit 412, Unit 41n). The input end of the first-stage sub-isolation feedback circuit Unit 401 is connected to the rectifier output circuit 300, and the output end is connected to the input end of the second-stage sub-isolation feedback circuit Unit 411; the input end of the last-stage sub-isolation feedback circuit Unit 41n is connected to the output end of the previous-stage sub-isolation feedback circuit Unit 41 (n-1), and the output end is connected to the chopping input control circuit 100; the input ends of the remaining sub-isolation feedback circuits are all connected to the output end of the previous-stage sub-isolation feedback circuit, and the output ends are all connected to the output end of the next-stage sub-isolation feedback circuit. The second-stage sub-isolation feedback circuit is used to integrate the voltage feedback signals output by multiple first-stage sub-isolation feedback circuits into one voltage feedback signal, and transmit it to the next-stage sub-isolation feedback circuit.

[0026] Furthermore, the first-level sub-isolation feedback circuit includes at least one sub-isolation feedback module. Taking the first-level sub-isolation feedback circuit Unit401 including multiple sub-isolation feedback modules (Unit401, Unit402, Unit40n) as an example, please refer to Figure 3. The input end of each sub-isolation feedback module is connected to the rectifier output circuit 300, and the output end is connected to the input end of the second-level sub-isolation feedback circuit Unit411; wherein, the sub-isolation feedback module is used to control the feedback weight of the output voltage of the rectifier output circuit according to the internal circuit parameters.

[0027] Specifically, taking the first sub-isolation feedback module as an example, the sub-isolation feedback module includes a first resistor R4011, a second resistor R4013, a third resistor R4012, a compensation circuit, a first optical coupler OC401 and a voltage regulator chip U401, and the compensation circuit includes a third capacitor C401; one end of the first resistor R4011 is connected to one end of the second resistor R4013, and the other end is connected to one end of the third resistor R4012, the other end of the second resistor R4013 is grounded, and the other end of the third resistor R4012 is connected to the first end of the first optical coupler OC401, The common connection end of the first resistor R4011 and the third resistor R4012 is connected to the rectifier output circuit 300; the first end of the voltage regulator chip U401 is connected to the second end of the first optocoupler OC401, the second end is grounded, and the third end is connected to the common connection end of the first resistor R4011 and the second resistor R4013; the third capacitor C401 is connected to one end of the first resistor R4011, and the other end is connected to the first end of the voltage regulator chip U401; the third end and the fourth end of the first optocoupler OC401 are both output ends of the first-stage sub-isolation feedback circuit Unit401.

[0028] In this embodiment, the circuit structure of each first-stage sub-isolation feedback module is exactly the same. Taking the first sub-isolation feedback module Unit401 as an example, Vo1 is the first output voltage, OC401 is the isolation optocoupler, and the primary and secondary creepage distance of the commonly used isolation optocoupler is about 8mm. Therefore, the single-stage isolation optocoupler cannot meet the requirements of reinforced insulation for creepage distance exceeding 800V DC. The design of the multi-stage isolation feedback circuit of this embodiment can use commonly used isolation optocouplers to achieve multi-channel isolation. By using a universal optocoupler isolation device, the safety distance requirements of high voltage levels can be met, which greatly reduces the difficulty of designing the feedback circuit at high voltage levels and reduces costs and procurement risks. U401 is a voltage regulator source. The voltage regulator chip model used in this embodiment is TL431, which is used to provide the sub-isolation feedback module with 2.5 V reference voltage; R4011 and R4013 can control the steady-state output of the sub-isolated feedback module to a specified voltage value. Specifically, the voltage output after voltage division by resistors R4011 and R4013 is compared with the reference voltage of U401, and then the output voltage of the sub-isolated feedback module is controlled to be stable at the specified value according to the comparison result; C401 is the compensation network of the loop, which is used to improve the stability and dynamic response speed of the loop. The compensation network can have only one capacitor or other impedance network to add zeros and poles to the loop; R4012 is used to control the current flowing through the OC401 optocoupler, that is, by controlling this resistor, the strength of the feedback signal can be controlled. The smaller the resistance, the greater the current of the same voltage feedback signal, and the greater the weight of this feedback. In actual design, it should be ensured that the optocoupler current is within the requirements of the specification under all working conditions.

[0029] Based on the above description of the first sub-isolation feedback module, in the two-stage multi-channel isolation feedback circuit of Figure 3, Uint40n represents the first-stage sub-isolation feedback circuit for the nth output. The optocoupler outputs of all first-stage sub-isolation feedback circuits are integrated in parallel to form a single feedback signal (Vc and Ve). The weight coefficients of each feedback circuit can be adjusted by adjusting the resistance of resistor R40n2. The integrated feedback signal is transmitted to the controller in the chopper input control circuit 100 via the second-stage sub-isolation feedback circuit. In the multi-stage multi-channel isolation feedback circuit of Figure 4, Unit41n represents the n+1th sub-isolation feedback circuit, which further isolates and feeds back the feedback signals from the previous stage, namely Vc41(n-1) and Ve41(n-1), to the next stage until they are fed back to the controller in the chopper input control circuit 100. The appropriate number of cascade feedback stages can be selected based on the actual safety distance requirements and the safety distance of the optocouplers.

[0030] Further, referring to Figures 2, 3 and 4, the circuit composition structures of the second-level sub-isolation feedback circuit Unit411 and the remaining sub-isolation feedback circuits are the same. Taking the second-level sub-isolation feedback circuit Unit411 as an example, the sub-isolation feedback circuit includes a fourth resistor R411 and a second optical coupler OC411; one end of the fourth resistor R411 is connected to the power supply VDD411, and the other end is the first input end of the second-level sub-isolation feedback circuit Unit411 or the remaining sub-isolation feedback circuits; the first end of the second optical coupler OC411 is the second input end of the second-level sub-isolation feedback circuit Unit411 or the remaining sub-isolation feedback circuits, the second end is grounded, and the third end and the fourth end are both It is the output end of the second-stage sub-isolation feedback circuit Unit411 or the remaining sub-isolation feedback circuits; the last-stage sub-isolation feedback circuit Unit41n includes a fifth resistor R41n, a sixth resistor R501 and a third optical coupler OC41n; one end of the fifth resistor R41n is connected to the power supply VDD41n, and the other end is the first input end of the last-stage sub-isolation feedback circuit Unit41n; the first end of the third optical coupler OC41n is the second input end of the last-stage sub-isolation feedback circuit Unit41n, the second end is grounded, the third end is connected to the chopping input control circuit 100, and the fourth end is connected to one end of the sixth resistor R501; the other end of the sixth resistor R501 is grounded.

[0031] Specifically, in this embodiment, taking the two-stage, two-way rectifier output in Figure 2 as an example, the second-stage sub-isolated feedback circuit Unit 411 integrates the feedback signals (Vc and Ve) from the two outputs. Specifically, the outputs of two isolated optocouplers (OC401 and OC402) are connected in parallel. OC411 is the isolating optocoupler of the second-stage sub-isolated feedback circuit, which further isolates and transmits the first-stage feedback signal to the chopper input control circuit 100. R411 is used to limit the current of OC411. VDD411 can be obtained from the windings of the main transformer. At the output of OC411, R501 converts the current signal fed back by the optocoupler into a voltage signal, VFB. VFB is the feedback voltage, which is transmitted to the controller for comparison with the primary current sampling signal. The controller then outputs the duty cycle through internal control logic to control the operation of the main switch. Resistor R501 in this embodiment can be either a pull-down resistor or a pull-up resistor. Multi-stage and multi-path only increase the number of sub-isolation feedback modules in the rectifier output circuit and the first-stage sub-isolation feedback circuit on this basis, and subsequently add multi-stage isolation feedback circuits to increase the safety distance. The principle and structure are exactly the same.

[0032] Figure 5 shows a schematic circuit diagram of another multi-stage, multi-channel isolated feedback circuit provided by this embodiment. This circuit differs from the embodiment corresponding to Figure 4 in that, while the first-stage sub-isolation feedback circuit in Figure 4 includes multiple sub-isolation feedback modules corresponding to the multiple isolated outputs, the second-stage and remaining sub-isolation feedback circuits are shared, saving hardware resources. Figure 5, on the other hand, represents a combination of multiple multi-stage isolated single-channel output circuits, with independent second-stage and remaining sub-isolation feedback circuits. This circuit can also implement isolated feedback control for any high-level input voltage and any multiple isolated outputs, providing practical benefits for certain special applications (e.g., those requiring special spatial layouts or requiring heavy loads on the power supply in the isolation feedback intermediate stage).

[0033] The switching power supply circuit with an ultra-wide voltage input range and multi-channel isolated output provided in the embodiments of the present application comprehensively considers factors such as circuit cost and complexity, selects the corresponding main circuit topology, and designs an isolated power transmission circuit with reinforced insulation between the primary and secondary sides, a secondary-side multi-channel rectifier output circuit, and a multi-stage multi-channel isolated feedback circuit while meeting relevant safety standards. The multi-channel isolated feedback circuit increases the safety distance through a multi-stage cascade method, thereby utilizing conventional isolation devices such as isolation optocouplers to achieve ultra-high voltage level feedback. At the same time, the multi-channel isolated feedback circuit integrates the multiple feedback signals into a single feedback signal in the second-stage isolation feedback circuit, which can then be fed back through multi-stage cascade feedback to achieve weighted feedback on the multiple isolated outputs. In summary, the multi-level multi-channel isolated feedback circuit can meet the isolation feedback requirements of any multi-channel isolated output, any high voltage level, and any safety distance based on the application of existing general-purpose optocoupler isolation devices, greatly reducing the design difficulty of the feedback circuit at high voltage levels, reducing costs and procurement risks; and can ensure better cross-regulation between multiple isolated outputs, with higher stability, reliability and power applicability, and can be applied to any main circuit topology, with high versatility.

[0034] It should be noted that the various embodiments in the present application are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0035] It should also be noted that, in the present application, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0036] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments shown herein but is intended to be applied in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A switching power supply circuit with multiple isolated outputs, characterized in that, Including: A chopper input control circuit, an isolation power transmission circuit, a rectifier output circuit, and an isolation feedback circuit; The isolation power transmission circuit and the isolation feedback circuit are respectively connected to the chopper input control circuit and the rectifier output circuit. The chopper input control circuit includes a switching tube, and the switching tube is electrically connected to the isolation power transmission circuit; The isolation power transmission circuit is configured to isolate and transmit the pulsating voltage input by the chopper input control circuit to the rectifier output circuit; The rectifier output circuit is configured to rectify the pulsating voltage output by the isolation power transmission circuit to obtain a DC voltage, and output multiple paths of the DC voltage to an external load; The isolation feedback circuit is configured to perform multi-stage isolation on the collected voltage feedback signal corresponding to the rectifier output circuit and transmit it to the chopper input control circuit; The chopper input control circuit is configured to control the on-off state of the switching tube according to the voltage feedback signal to adjust the DC voltage to a preset voltage index.

2. The switching power supply circuit according to claim 1, wherein The rectifier output circuit includes any one of the following: a single-channel rectifier output circuit, a multi-channel isolation rectifier output circuit; wherein, the multi-channel isolation rectifier output circuit includes a plurality of sub-rectifier output modules. The sub-rectifier output module includes a diode and a second capacitor. The positive electrode of the diode is connected to the first end of the second winding of the transformer, the negative electrode is connected to the isolation feedback circuit, and the second end of the second winding is grounded; one end of the second capacitor is connected to the negative electrode of the diode, and the other end is connected to the second end of the second winding.

3. The switching power supply circuit according to claim 1, wherein The chopper input control circuit includes a controller and an input chopper circuit. The controller is respectively electrically connected to the input chopper circuit and the isolation feedback circuit.

4. The switching power supply circuit according to claim 3, characterized in that, The input chopper circuit includes a plurality of series-connected flyback circuits. The first flyback circuit is connected to the positive electrode of the power supply, and the last flyback circuit is connected to the negative electrode of the power supply. The flyback circuit includes a first capacitor and the switching tube. The isolation power transmission circuit includes a transformer. One end of the first capacitor is connected to the first end of the first winding of the transformer, and the other end is connected to the first end of the switching tube; the second end of the switching tube is connected to the controller, and the third end is connected to the second end of the first winding.

5. The switching power supply circuit according to claim 3, wherein, The controller is configured to: calculate the duty ratio of the driving signal according to the voltage feedback signal and the input current sampling signal, and output a corresponding driving signal according to the duty ratio; wherein, the driving signal is used to control the on-off state of the switching tube to adjust the DC voltage.

6. The switching power supply circuit according to claim 1, wherein, The isolation feedback circuit includes multiple levels of sub-isolation feedback circuits. The input end of the first-level sub-isolation feedback circuit is connected to the rectification output circuit, and the output end is connected to the input end of the second-level sub-isolation feedback circuit; the input end of the last-level sub-isolation feedback circuit is connected to the output end of the previous-level sub-isolation feedback circuit, and the output end is connected to the chopping input control circuit; the input ends of the remaining sub-isolation feedback circuits are all connected to the output end of the previous-level sub-isolation feedback circuit, and the output ends are all connected to the output end of the next-level sub-isolation feedback circuit. The second-level sub-isolation feedback circuit is used to integrate the voltage feedback signals output by multiple first-level sub-isolation feedback circuits into one voltage feedback signal and transmit it to the next-level sub-isolation feedback circuit.

7. The switching power supply circuit according to claim 6, characterized in that, The first-level sub-isolation feedback circuit includes at least one sub-isolation feedback module. The input end of the sub-isolation feedback module is connected to the rectification output circuit, and the output end is connected to the input end of the second-level sub-isolation feedback circuit; wherein, the sub-isolation feedback module is used to control the feedback weight of the output voltage of the rectification output circuit according to the internal circuit parameters.

8. The switching power supply circuit according to claim 7, characterized in that, The sub-isolation feedback module includes a first resistor, a second resistor, a third resistor, a compensation circuit, a first optocoupler, and a voltage regulator chip. The compensation circuit includes a third capacitor; one end of the first resistor is connected to one end of the second resistor, and the other end is connected to one end of the third resistor. The other end of the second resistor is grounded, and the other end of the third resistor is connected to the first end of the first optocoupler. The common connection end of the first resistor and the third resistor is connected to the rectification output circuit; the first end of the voltage regulator chip is connected to the second end of the first optocoupler, the second end is grounded, and the third end is connected to the common connection end of the first resistor and the second resistor; the third capacitor is connected to one end of the first resistor, and the other end is connected to the first end of the voltage regulator chip; the third end and the fourth end of the first optocoupler are both the output ends of the first-level sub-isolation feedback circuit.

9. The switching power supply circuit according to claim 6, characterized in that, The second-level sub-isolation feedback circuit and the remaining sub-isolation feedback circuits both include a fourth resistor and a second optocoupler; one end of the fourth resistor is connected to the power supply, and the other end is the first input end of the second-level sub-isolation feedback circuit or the remaining sub-isolation feedback circuits; the first end of the second optocoupler is the second input end of the second-level sub-isolation feedback circuit or the remaining sub-isolation feedback circuits, the second end is grounded, and the third end and the fourth end are both the output ends of the second-level sub-isolation feedback circuit or the remaining sub-isolation feedback circuits.

10. The switching power supply circuit according to claim 6, wherein The last-level sub-isolation feedback circuit includes a fifth resistor, a sixth resistor, and a third optocoupler; one end of the fifth resistor is connected to the power supply, and the other end is the first input end of the last-level sub-isolation feedback circuit; the first end of the third optocoupler is the second input end of the last-level sub-isolation feedback circuit, the second end is grounded, the third end is connected to the chopping input control circuit, and the fourth end is connected to one end of the sixth resistor; the other end of the sixth resistor is grounded.

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