Multipath output detection circuit and switching power supply

Abstract

The utility model provides a multipath output detection circuit and a switching power supply, and relates to the technical field of switching power supplies. The multipath output detection circuit comprises a detection module, a selection switch module and a control module. The detection module comprises a plurality of detection units, and the detection units are in one-to-one correspondence with the direct-current output links so as to detect output voltages of the direct-current output links and obtain sampling voltages. The selection switch module at least comprises a first transmission channel and a second transmission channel, and the sampling voltage is transmitted to the control module through the first transmission channel or the second transmission channel. And when the sampling voltage is smaller than the preset value, the control module sends a control signal to the rear-end load to adjust the load power. According to the utility model, under the condition that the number of sampling ports is not changed, the output state of each winding group can be rapidly monitored, so that a detection signal can be timely fed back to a control device when power failure occurs, the power of a rear-end load can be rapidly adjusted, and the operation state of the grid-connected inverter can be maintained.

Description

Technical Field

[0001] The utility model relates to the technical field of switching power supplies, in particular to a multi-channel output detection circuit and a switching power supply. Background Art

[0002] In addition to converting DC power into AC power, the grid-connected inverter can also synchronize the frequency and phase of the output AC power with the mains power so that the output AC power can be returned to the mains power. Grid-connected inverters are often used in applications where a DC voltage power supply is connected to the power grid. Among them, the switching power supply often sets multiple DC voltage outputs on the secondary winding of the switching power supply to meet the needs of the grid-connected inverter.

[0003] Normally, when the output of a switching power supply is abnormal in some winding groups during actual use, it will cause instability in the subsequent stage and abnormal operation of the machine. In the prior art, based on the consideration of the number of sampling ports of the control device in the grid-connected inverter, except for the DC voltage output corresponding to the main winding, which will be set with voltage feedback, other winding groups will not perform voltage detection.

[0004] In summary, there is an urgent need for a detection circuit that can quickly monitor the output status of each winding group output in the switching power supply without changing the number of sampling ports corresponding to the control device, so as to promptly feedback the detection signal to the control device when power failure occurs, and then quickly adjust the back-end load power through the control device to maintain the operating status of the grid-connected inverter. Utility Model Content

[0005] The purpose of the utility model is to provide a multi-channel output detection circuit and a switching power supply, which can quickly monitor the output status of each winding group output in the switching power supply without changing the number of sampling ports corresponding to the control device, so as to timely feedback the detection signal to the control device when power failure occurs, and then quickly adjust the rear-end load power through the control device to maintain the operating state of the grid-connected inverter.

[0006] The utility model provides a technical solution:

[0007] In a first aspect, the utility model provides a multi-channel output detection circuit, which is applied to a switching power supply, wherein the switching power supply includes a multi-channel DC output link, and the multi-channel output detection circuit includes a detection module, a selection switch module and a control module, wherein the detection module includes a plurality of detection units; each of the detection units corresponds to the DC output link one by one to detect the output voltage of each DC output link and obtain a sampled voltage; each of the detection units is connected to the control module through the selection switch module; the selection switch module includes at least a first transmission channel and a second transmission channel, and the sampled voltage is transmitted to the control module through the first transmission channel or the second transmission channel;

[0008] When the sampled voltage is less than a preset value, the control module sends a control signal to the rear-end load to adjust the load power.

[0009] Preferably, the selection switch module includes multiple working states; the control module is also connected to the enable end of the selection switch module to send an enable signal to the selection switch module to switch the working state of the selection switch module;

[0010] Wherein, when the control module sends the first enable signal to the selection switch module, the selection switch module is in a conducting state of the first transmission channel;

[0011] When the control module sends a second enable signal to the selection switch module, the selection switch module is in a second transmission channel conducting state.

[0012] Preferably, the selection switch module at least includes a first input end, a second input end and an output end; the first input end and the second input end each include a plurality of input ports, each of the input ports corresponds to and is connected with a data output port of the detection unit; the output end is connected with a data input port of the control module; the input port corresponding to the first input end and the output end constitute the first transmission channel; the input port corresponding to the second input end and the output end constitute the second transmission channel;

[0013] When the selection switch module is in the first transmission channel conducting state, the first input end is turned on and the second input end is turned off;

[0014] When the selection switch module is in the second transmission channel conducting state, the first input end is closed and the second input end is turned on.

[0015] Preferably, the output end includes a plurality of output ports, each of which corresponds to and is connected to a data input port of the control module; wherein the number of the output ports is less than the number of the input ports;

[0016] Preferably, the detection unit includes an operational amplifier subunit, an input end of the operational amplifier subunit is connected to any of the DC output links, and an output end of the operational amplifier subunit is connected to an input end of the selection switch module, wherein the operational amplifier subunit is used to adjust the amplification factor of the output voltage to obtain a sampling voltage.

[0017] Preferably, the operational amplifier subunit includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor; the first end of the first resistor is grounded, and the second end of the first resistor is respectively connected to the second end of the second resistor and the first input end of the operational amplifier; the first end of the second resistor is connected to any one of the DC output links; the first end of the third resistor is grounded; the second end of the third resistor is respectively connected to the first end of the fourth resistor and the second input end of the operational amplifier; the second end of the fourth resistor is connected to the output end of the operational amplifier; the output end of the operational amplifier is also connected to the input end of the selection switch module.

[0018] Preferably, the operational amplifier subunit further includes a current limiting resistor, a first end of the current limiting resistor is connected to the output end of the operational amplifier; and a second end of the current limiting resistor is connected to the input end of the selection switch module.

[0019] Preferably, the operational amplifier subunit further includes a first filter capacitor, a first end of the first filter capacitor is connected to a first end of the fourth resistor; and a second end of the first filter capacitor is connected to a second end of the fourth resistor.

[0020] Preferably, the operational amplifier subunit further includes a second filter capacitor, a first end of the second filter capacitor is connected to the output end of the operational amplifier; and a second end of the second filter capacitor is grounded.

[0021] In a second aspect, the utility model provides a switching power supply, comprising a multi-channel DC output link and a multi-channel output detection circuit as described in any one of the first aspects above, wherein the multi-channel output detection circuit is connected to the DC output link and is used to detect the output voltage of the DC output link.

[0022] The beneficial effects of a multi-channel output detection circuit and a switching power supply provided by the utility model are:

[0023] A multi-channel output detection circuit is applied to a switching power supply, which includes a multi-channel DC output link. The multi-channel output detection circuit includes a detection module, a selection switch module and a control module. The detection module includes a plurality of detection units, each detection unit corresponds to a DC output link one by one, so as to detect the output voltage of each DC output link and obtain a sampled voltage. Each detection unit is connected to the control module through a selection switch module, and the selection switch module at least includes a first transmission channel and a second transmission channel. The sampled voltage is transmitted to the control module through the first transmission channel or the second transmission channel. When the sampled voltage is less than a preset value, the control module sends a control signal to the rear-end load to adjust the load power. The utility model can quickly monitor the output state of each winding group output in the switching power supply without changing the number of sampling ports corresponding to the control device, so as to timely feedback the detection signal to the control device when power failure occurs, and then quickly adjust the rear-end load power through the control device to maintain the operating state of the grid-connected inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of the structure of a multi-channel output detection circuit provided by the utility model;

[0026] Figure 2 It is a schematic diagram of the transmission path of the sampling voltage in the utility model;

[0027] Figure 3 This is a structural schematic diagram of the switch module selected in the utility model;

[0028] Figure 4 It is a structural schematic diagram of the detection unit in the utility model;

[0029] Figure 5 This is one of the circuit principle diagrams of the detection unit in the utility model;

[0030] Figure 6 This is the second schematic diagram of the circuit principle of the detection unit in the utility model;

[0031] Figure 7 This is a structural schematic diagram of the switching power supply provided by the utility model.

[0032] Icon: 100-multi-output detection circuit; 200-switching power supply; 101-selection switch module; 102-detection module; 103-control module; 201-detection unit; 202-operational amplifier subunit; U1-operational amplifier; R1-first resistor; R2-second resistor; R3-third resistor; R4-fourth resistor; R5-current limiting resistor; C1-first filter capacitor; C2-second filter capacitor. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0036] In the description of the present utility model, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present utility model.

[0037] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0038] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] As described in the background technology, the switching power supply often sets multiple DC voltage outputs on the secondary winding of the switching power supply to meet the needs of the grid-connected inverter. When the output of individual winding groups in the switching power supply is abnormal, it will cause unstable operation of the subsequent stage and abnormal operation of the grid-connected inverter. And based on the consideration of the number of sampling ports of the control device in the grid-connected inverter, except for the DC voltage output corresponding to the main winding, which will set the voltage feedback accordingly, other winding groups will not perform voltage detection.

[0040] Based on the above considerations, the utility model provides a detection scheme that can quickly monitor the output status of each winding group output in the switching power supply without changing the number of sampling ports corresponding to the control device, so as to promptly feedback the detection signal to the control device when power failure occurs, and then quickly adjust the back-end load power through the control device to maintain the operating status of the grid-connected inverter.

[0041] The detection scheme will be described in detail below.

[0042] Example

[0043] See also Figure 1 In a first aspect, the utility model provides a multi-channel output detection circuit 100, which is applied to a switching power supply 200. The switching power supply 200 includes a multi-channel DC output link. The multi-channel output detection circuit 100 includes a detection module 102, a selection switch module 101 and a control module 103. The detection module 102 includes a plurality of detection units 201; each detection unit 201 corresponds to a DC output link one by one to detect the output voltage of each DC output link and obtain a sampled voltage; each detection unit 201 is connected to the control module 103 through the selection switch module 101.

[0044] The selection switch module 101 includes at least a first transmission channel and a second transmission channel. Figure 2 ,Should Figure 2 The transmission path of the sampling voltage is shown, wherein the sampling voltage can be transmitted to the control module through the first transmission channel or the second transmission channel. When the sampling voltage is less than a preset value, the control module sends a control signal to the rear-end load to adjust the load power.

[0045] In this embodiment, the switching power supply includes multiple DC output links, which can provide multiple DC outputs to the back end. The detection module in the multiple output detection circuit is used to detect the output voltage provided by each DC output link to determine whether the corresponding DC output has a voltage drop. If a voltage drop occurs, that is, when the sampled voltage is lower than a preset value, the control unit can output a control signal to the load in the first and second stages to adjust the load power of the device, or send a control signal to the switching power supply to cut off the corresponding DC output link, thereby improving the operating reliability of the switching power supply or the grid-connected inverter.

[0046] In a possible implementation, the control module 103 may send an enable signal to the selection switch module 101 to switch the corresponding working state of the selection switch module 101. The control module 103 is connected to the enable end of the selection switch module 101. When the control module 103 sends a first enable signal to the selection switch module 101, the selection switch module 101 is in a first transmission channel conduction state; when the control module 103 sends a second enable signal to the selection switch module 101, the selection switch module 101 is in a second transmission channel conduction state.

[0047] In a possible implementation, the enable signal may be a periodic signal of a preset sampling time. Taking a high level as the first enable signal and a low level as the second enable signal, and taking microsecond period detection as an example, when the control module 103 sends a high level to the selection switch module 101, the selection switch module 101 is in a first transmission channel conduction state; when the control module 103 sends a low level to the selection switch module 101, the selection switch module 101 is in a second transmission channel conduction state.

[0048] The selection switch module 101 at least includes a first input terminal, a second input terminal and an output terminal. The first input terminal and the second input terminal each include a plurality of input ports, each of which corresponds to and is connected to a data output port of the detection unit 201. The output terminal is connected to a data input port of the control module 103. The input port corresponding to the first input terminal and the output terminal constitute a first transmission channel; the input port corresponding to the second input terminal and the output terminal constitute a second transmission channel.

[0049] When the control module 103 sends a high level to the selection switch module 101, the selection switch module 101 is in a first transmission channel conduction state, the first input terminal is turned on, and the second input terminal is turned off;

[0050] When the control module 103 sends a low level to the selection switch module 101 , the selection switch module 101 is in a second transmission channel conducting state, the first input terminal is closed, and the second input terminal is turned on.

[0051] Specifically, please refer to Figure 3 , Figure 3It is a structural schematic diagram of the switch module selected in this embodiment. When the switching power supply 200 includes six DC output links, each output voltage corresponds to 24V, 18V, 15V, 12V, 7V and 5V, respectively, and each DC output link corresponds to a detection unit to obtain a sampled voltage. Taking the DC output link corresponding to 24V as an example, the sampled voltage can be expressed as 24V-AD. Among them, pins 2, 3, 5, 6, 10 and 11 of the switch module 101 are selected as input ports, and the sampled voltages obtained by the above-mentioned output voltages correspond one by one. Pin 1 of the switch module 101 is selected as an enable terminal to receive high and low level signals. Pins 4, 7 and 9 of the switch module 101 are selected as output terminals, which are respectively connected to the data ports of the control module.

[0052] Among them, pin 2, pin 3 and pin 5 of the selection switch module 101 are selected as the ports corresponding to the first input end. Pin 2, pin 3 and pin 5 of the selection switch module 101 can correspond to pin 4, pin 7 and pin 9 of the selection switch module 101 one by one. At this time, three channels can be obtained, and the three channels can be used as the first transmission channel.

[0053] Similarly, with pins 6, 10 and 11 of the selection switch module 101 as the ports corresponding to the second input end, the pins 6, 10 and 11 of the selection switch module 101 can correspond one-to-one with pins 4, 7 and 9 of the selection switch module 101, and three channels can be obtained at this time, and the three channels can be used as the second transmission channels.

[0054] Specifically, when the sampling time is: 0-10ms, when the enable signal S=1 (high level), the first transmission channel is turned on, and the sampling voltage 24V-AD corresponding to the 24V DC output link can be output to the first data port CH1 of the MCU; the sampling voltage 18V-AD corresponding to the 18V DC output link can be output to the second data port CH2 of the MCU; the sampling voltage 15V-AD corresponding to the 15V DC output link can be output to the third data port CH3 of the MCU.

[0055] When the sampling time is: 11-20ms, when the enable signal S=0 (low level), the second transmission channel is turned on, and the sampling voltage 12V-AD corresponding to the 12V DC output link can be output to the first data port CH1 of the MCU; the sampling voltage 7V-AD corresponding to the 7V DC output link can be output to the second data port CH2 of the MCU; the sampling voltage 5V-AD corresponding to the 5V DC output link can be output to the third data port CH3 of the MCU.

[0056] It should be noted that in this embodiment, the number of input ports and output ports of the selection switch module is not limited, as long as the number of output ports is consistent with the data ports of the control unit, even if each output port corresponds to and is connected to the data input port of the control module one by one.

[0057] In this embodiment, the number of output ports may be less than the number of input ports, and each input port is connected to an output end of the detection unit in a one-to-one correspondence.

[0058] In summary, this embodiment can realize the output state detection of each winding group output without changing the number of sampling ports corresponding to the control device, and realize the detection of the corresponding channel through simple enable control. The purpose of the enable signal is to switch the corresponding channel. In a possible implementation method, the enable signal can be a pseudo-random code sequence (for example, 00, 01, etc.), and the above pseudo-random code sequence corresponds to a specific transmission channel, so that the sampled voltage is transmitted through the corresponding transmission channel.

[0059] In this embodiment, please refer to Figure 4 The detection unit 201 includes an operational amplifier subunit 202, an input end of the operational amplifier subunit 202 is connected to any DC output link, and an output end of the operational amplifier subunit 202 is connected to an input end of the selection switch module, wherein the operational amplifier subunit 202 is used to adjust the amplification factor of the output voltage to obtain a sampling voltage.

[0060] In a possible implementation, the operational amplifier subunit 202 may be a differential operational amplifier U1. The differential operational amplifier U1 includes an operational amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The structure of the differential operational amplifier U1 can be referred to in Figure 5 , the first end of the first resistor R1 is grounded, the second end of the first resistor R1 is respectively connected to the second end of the second resistor R2 and the first input end of the operational amplifier U1; the first end of the second resistor R2 is connected to any DC output link to receive the output voltage; the first end of the third resistor R3 is grounded; the second end of the third resistor R3 is respectively connected to the first end of the fourth resistor R4 and the second input end of the operational amplifier U1; the second end of the fourth resistor R4 is connected to the output end of the operational amplifier U1; the output end of the operational amplifier U1 is also connected to the input end of the selection switch module.

[0061] Among them, the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are differential operational amplifier resistors. The output voltage of the differential operational amplifier can be adjusted by adjusting the resistance values ​​corresponding to the first resistor R1, the second resistor R2 or the third resistor R3 and the fourth resistor R4. Taking the 15V DC output link as an example, the differential operational amplifier corresponds to the output sampling voltage 15V-AD. Among them, the value of the sampling voltage 15V-AD satisfies the calculation formula: 15V-AD = UIN*(R1 / R2), UIN is the output voltage corresponding to any DC output link, when the output voltage corresponding to the DC output link is 15V, the resistance values ​​of the first resistor R1 and the second resistor R2 can be 2K and 10K respectively. At this time, the value corresponding to the sampling voltage 15V-AD is 3V.

[0062] When the voltage of the 15V DC output link drops, assuming that the voltage drops to 12V, according to the above calculation formula, the value corresponding to the corresponding sampling voltage 15V-AD is 2.4V. At this time, the preset value of the control module 103 can be set to 3V. Once the value of the sampling voltage is detected to be less than 3V, the control module 103 sends a control signal to the subsequent load to adjust the load power.

[0063] In this embodiment, the control module can be prevented from being accidentally touched by setting a preset value, that is, in order to avoid the instability of the instantaneous output voltage of the DC output link, the control module directly drives the back-end load adjustment. Taking the 15V DC output link as an example, it can be set to trigger the back-end load adjustment when the output voltage drops by more than 20%. That is, when the output voltage corresponding to the 15V DC output link is less than 12V (or when the sampling voltage corresponding to the 15V DC output link is less than 2.4V), the back-end load adjustment is triggered.

[0064] It should be noted that, although the output of the sampling voltage can be adjusted by the first resistor R1, the second resistor R2 or the third resistor R3, the fourth resistor R4, the preset value is adjusted based on the fixed corresponding first resistor R1, the second resistor R2 or the third resistor R3, the fourth resistor R4.

[0065] Please refer to Figure 6 In order to ensure the stable operation of the operational amplifier subunit 202 and provide a stable sampling voltage, the operational amplifier subunit 202 further includes a current limiting resistor R5, a first end of the current limiting resistor R5 is connected to the output end of the operational amplifier U1; a second end of the current limiting resistor R5 is connected to the input end of the selection switch module.

[0066] Please continue to refer to Figure 6 The operational amplifier subunit 202 further includes a first filter capacitor C1, a first end of the first filter capacitor C1 is connected to a first end of the fourth resistor R4; and a second end of the first filter capacitor C1 is connected to a second end of the fourth resistor R4.

[0067] Please continue to refer to Figure 6 The operational amplifier subunit 202 further includes a second filter capacitor C2, a first end of the second filter capacitor C2 is connected to the output end of the operational amplifier U1; and a second end of the second filter capacitor C2 is grounded.

[0068] In summary, the present embodiment provides a multi-channel output detection circuit, which is applied to a switching power supply, and the switching power supply includes a multi-channel DC output link, and the multi-channel output detection circuit includes a detection module, a selection switch module and a control module. Among them, the detection module includes a plurality of detection units, each detection unit corresponds to a DC output link one by one, so as to detect the output voltage of each DC output link and obtain a sampled voltage. Each detection unit is connected to the control module through a selection switch module, and the selection switch module at least includes a first transmission channel and a second transmission channel, and the sampled voltage is transmitted to the control module through the first transmission channel or the second transmission channel. Among them, when the sampled voltage is less than a preset value, the control module sends a control signal to the rear-end load to adjust the load power. The utility model can quickly monitor the output state of each winding group output in the switching power supply without changing the number of sampling ports corresponding to the control device, so as to promptly feedback the detection signal to the control device when power failure occurs, and then quickly adjust the rear-end load power through the control device to maintain the operating state of the grid-connected inverter.

[0069] Second, please refer to Figure 7 The utility model provides a switching power supply 200, comprising a multi-channel DC output link and a multi-channel output detection circuit 100 of any one of the above-mentioned first aspects, the multi-channel output detection circuit 100 is connected to the DC output link and is used to detect the output voltage of the DC output link.

[0070] The switching power supply in this embodiment includes all the technical means and technical effects of the first aspect mentioned above, that is, it is capable of quickly monitoring the output status of each winding group output in the switching power supply without changing the number of sampling ports corresponding to the control device, so as to promptly feedback the detection signal to the control device when power failure occurs, and then quickly adjust the rear-end load power through the control device to maintain the operating status of the grid-connected inverter.

[0071] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A multi-channel output detection circuit, applied to a switching power supply, wherein the switching power supply includes a multi-channel DC output link, characterized in that: The multi-channel output detection circuit includes a detection module, a selection switch module and a control module. The detection module includes a plurality of detection units; each detection unit corresponds to the DC output link one by one to detect the output voltage of each DC output link and obtain a sampled voltage; each detection unit is connected to the control module through the selection switch module; the selection switch module includes at least a first transmission channel and a second transmission channel, and the sampled voltage is transmitted to the control module through the first transmission channel or the second transmission channel; When the sampled voltage is less than a preset value, the control module sends a control signal to the rear-end load to adjust the load power.

2. The multi-channel output detection circuit according to claim 1, characterized in that: The selection switch module includes multiple working states; the control module is also connected to the enable end of the selection switch module to send an enable signal to the selection switch module to switch the working state of the selection switch module, wherein: When the control module sends a first enable signal to the selection switch module, the selection switch module is in a first transmission channel conducting state; When the control module sends a second enable signal to the selection switch module, the selection switch module is in a second transmission channel conducting state.

3. The multi-channel output detection circuit according to claim 2, characterized in that: The selection switch module at least includes a first input end, a second input end and an output end; the first input end and the second input end each include a plurality of input ports, each of the input ports corresponds to and is connected with a data output port of the detection unit; the output end is connected with a data input port of the control module; the input port corresponding to the first input end and the output end constitute the first transmission channel; the input port corresponding to the second input end and the output end constitute the second transmission channel; When the selection switch module is in the first transmission channel conducting state, the first input end is turned on and the second input end is turned off; When the selection switch module is in the second transmission channel conducting state, the first input end is closed and the second input end is turned on.

4. The multi-channel output detection circuit according to claim 3, characterized in that: The output end includes a plurality of output ports, each of which corresponds to and is connected to a data input port of the control module in a one-to-one manner; wherein the number of the output ports is less than the number of the input ports.

5. The multi-channel output detection circuit according to claim 1, characterized in that: The detection unit includes an operational amplifier subunit, the input end of the operational amplifier subunit is connected to any of the DC output links, and the output end of the operational amplifier subunit is connected to the input end of the selection switch module, wherein the operational amplifier subunit is used to adjust the amplification factor of the output voltage to obtain a sampling voltage.

6. The multi-channel output detection circuit according to claim 5, characterized in that: The operational amplifier subunit includes an operational amplifier, a first resistor, a second resistor, a third resistor and a fourth resistor. The first end of the first resistor is grounded, and the second end of the first resistor is respectively connected to the second end of the second resistor and the first input end of the operational amplifier; the first end of the second resistor is connected to any one of the DC output links; the first end of the third resistor is grounded; the second end of the third resistor is respectively connected to the first end of the fourth resistor and the second input end of the operational amplifier; the second end of the fourth resistor is connected to the output end of the operational amplifier; and the output end of the operational amplifier is also connected to the input end of the selection switch module.

7. The multi-channel output detection circuit according to claim 6, characterized in that: The operational amplifier subunit further includes a current limiting resistor, a first end of the current limiting resistor is connected to the output end of the operational amplifier; and a second end of the current limiting resistor is connected to the input end of the selection switch module.

8. The multi-channel output detection circuit according to claim 6, characterized in that: The operational amplifier subunit further includes a first filter capacitor, a first end of the first filter capacitor is connected to a first end of the fourth resistor; and a second end of the first filter capacitor is connected to a second end of the fourth resistor.

9. The multi-channel output detection circuit according to claim 6, characterized in that: The operational amplifier subunit further includes a second filter capacitor, a first end of the second filter capacitor is connected to the output end of the operational amplifier; and a second end of the second filter capacitor is grounded.

10. A switching power supply, characterized in that: It comprises a multi-channel DC output link and a multi-channel output detection circuit as claimed in any one of claims 1 to 9, wherein the multi-channel output detection circuit is connected to the DC output link and is used to detect the output voltage of the DC output link.

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