UPS (Uninterrupted Power Supply) and power supply circuit thereof

Abstract

The invention discloses a UPS (Uninterrupted Power Supply) and a power supply circuit thereof. The power supply circuit comprises a first switch module which is controlled by a first control signal and is set to be in a normally open state; the input end of the first switch module receives a first input voltage from a mains supply end and outputs a first output voltage from the output end; the second switch module is controlled by a second control signal and is set to be in a normally open state; the input end of the second switch module receives a second input voltage from the storage battery power supply end and outputs a second output voltage from the output end; the positive electrode of the power diode is connected with the output end of the second switch module, and the negative electrode is connected with the output end of the first switch module and connected to a load power supply end. According to the power supply circuit, when the mains supply input fails and loses voltage, the control signal formed and sent by the main control chip based on real-time monitoring of the mains supply state does not need to be waited, the storage battery power supply can be immediately and automatically connected to the load power supply end, and the delay time of switching from the mains supply power supply to the storage battery power supply in the UPS power supply is greatly shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of UPS power supply and relates to a UPS power supply and a power supply circuit thereof. Background Art

[0002] An uninterruptible power supply (UPS) is a device that can continuously supply power to a load. A UPS power supply usually consists of the following parts: mains input, rectifier, inverter, and battery. When the mains input is normal, the input mains is rectified by the rectifier, and then the inverter is used to supply power to the load and the battery is charged. When the mains input fails and loses voltage, the energy stored in the battery is used to supply power to the load through the inverter, thereby achieving uninterrupted power supply to the load.

[0003] The power supply circuit of an existing UPS power supply usually needs to be provided with a power supply switching module. When the AC input fails and loses voltage, the power supply switching module switches from the AC power supply mode to the battery power supply mode. The control process of the power supply switching module generally includes: the main control chip monitors the AC input status in real time. When the AC power loses voltage, the main control chip sends a control signal, and the power supply switching module switches to the battery power supply mode in response to the control signal. Therefore, there is a certain delay time when switching from the AC power supply mode to the battery power supply mode. This delay time is an important indicator for evaluating the performance of the UPS power supply.

[0004] At present, the switching delay time of general UPS power supply can reach about 20ms, and the better UPS power supply can reach 7ms to 15ms. Such switching speed can meet the requirements for most application scenarios and will not cause the UPS power supply to cause the subsequent load to fail due to the power supply mode switching. However, for high-precision electronic equipment and other application places with strict switching time requirements, there will still be hidden dangers of failure. Therefore, how to further reduce the delay time of switching from AC power supply to battery power supply in UPS power supply is a problem that needs to be solved. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a UPS power supply and a power supply circuit thereof to solve the problem of how to further reduce the delay time of switching from mains power supply to battery power supply in the UPS power supply.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A power supply circuit of a UPS power supply, comprising:

[0008] A first switch module, controlled by a first control signal and set to a normally open state; an input end of the first switch module receives a first input voltage from a mains power supply end and outputs a first output voltage from an output end;

[0009] A second switch module, controlled by a second control signal and set to a normally open state; the input end of the second switch module receives a second input voltage from the battery power supply end and outputs a second output voltage from the output end;

[0010] A power diode, wherein the anode of the power diode is connected to the output end of the second switch module, and the cathode of the power diode is connected to the output end of the first switch module and to the load power supply end.

[0011] Preferably, the first switch module includes a first MOS switch tube, a source of the first MOS switch tube serves as an input end to receive the first input voltage, a drain of the first MOS switch tube serves as an output end to output the first output voltage, and a gate of the first MOS switch tube is controlled by the first control signal so that the first MOS switch tube is in a normally open state.

[0012] Preferably, the first switch module also includes a second MOS switch tube, the first MOS switch tube is a PMOS tube, and the second MOS switch tube is an NMOS tube; wherein a first resistor and a first capacitor are connected in parallel between the source and the gate of the first MOS switch tube, the source of the second MOS switch tube is connected to the ground, the drain of the second MOS switch tube is connected to the gate of the first MOS switch tube through the second resistor, and the gate of the second MOS switch tube receives the first control signal provided by the main control chip.

[0013] Preferably, the second switch module includes a third MOS switch tube, the source of the third MOS switch tube serves as an input end to receive the second input voltage, the drain of the third MOS switch tube serves as an output end to output the second output voltage, and the gate of the third MOS switch tube is controlled by the second control signal so that the third MOS switch tube is in a normally open state.

[0014] Preferably, the second switch module also includes a fourth MOS switch tube, the third MOS switch tube is a PMOS tube, and the fourth MOS switch tube is an NMOS tube; wherein, a third resistor and a second capacitor are connected in parallel between the source and the gate of the third MOS switch tube, the source of the fourth MOS switch tube is connected to the ground, the drain of the fourth MOS switch tube is connected to the gate of the third MOS switch tube through a fourth resistor, and the gate of the fourth MOS switch tube receives the second control signal provided by the main control chip.

[0015] Preferably, the power diode is a high current Schottky diode.

[0016] Preferably, the power supply circuit also includes a third switch module, which is controlled by a third control signal and is set to a normally closed state; the input end of the third switch module is connected to the output end of the second switch module, and the output end of the third switch module is interconnected with the cathode of the power diode and connected to the load power supply end; when the AC power supply end cannot supply power normally and the power diode is turned on, the third control signal controls the third switch module to an open state.

[0017] Preferably, the third switch module includes a fifth MOS switch tube, the drain of the fifth MOS switch tube is connected to the output end of the second switch module as an input end, the source of the fifth MOS switch tube is connected to the negative electrode of the power diode as an output end and connected to the load power supply end, and the gate of the fifth MOS switch tube is controlled by the third control signal so that the fifth MOS switch tube is in a normally off state.

[0018] Preferably, the third switch module also includes a sixth MOS switch tube, the fifth MOS switch tube is a PMOS tube, and the sixth MOS switch tube is an NMOS tube; wherein, a fifth resistor and a third capacitor are connected in parallel between the source and the gate of the fifth MOS switch tube, the source of the sixth MOS switch tube is connected to the ground, the drain of the sixth MOS switch tube is connected to the gate of the fifth MOS switch tube through the sixth resistor, and the gate of the sixth MOS switch tube receives the third control signal provided by the main control chip.

[0019] Another aspect of the present invention is to provide a UPS power supply, which includes the power supply circuit as described above.

[0020] The UPS power supply and its power supply circuit provided by the embodiment of the present invention are provided with a first switch module and a second switch module in a normally open state in the power supply circuit, and the output ends of the first switch module and the second switch module are connected through a power diode, the mains voltage is connected via the first switch module to form a first output voltage to supply power to the load and is connected to the negative pole of the power diode in real time, and the battery voltage is connected via the second switch module to form a second output voltage to be connected to the positive pole of the power diode in real time. The characteristics of the UPS power supply system itself are utilized and combined with the conduction characteristics of the power diode: when the mains power supply end is supplying power normally, the first output voltage is greater than the second output voltage, the power diode is cut off, and the first output voltage output by the first switch module is connected to the load power supply end to supply power to the load; when the mains power supply end is abnormal and cannot supply power normally, the first output voltage loses pressure and is less than the second output voltage, the power diode is turned on, and the second output voltage output by the second switch module is connected to the load power supply end via the power diode to supply power to the load. Therefore, in this power supply circuit, when the AC input fails and the voltage is lost, and it is necessary to switch from the AC power supply mode to the battery power supply mode, there is no need to wait for the control signal generated and sent by the main control chip based on real-time monitoring of the AC power status. The battery power supply can be automatically connected to the load power supply end immediately, which greatly reduces the delay time of switching from AC power supply to battery power supply in the UPS power supply and improves the performance of the UPS power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural block diagram of a power supply circuit of a UPS power supply in an embodiment of the present invention;

[0022] Figure 2 4 is a circuit diagram of a power supply circuit of a UPS power supply in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present invention clearer, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Examples of these preferred embodiments are illustrated in the accompanying drawings. The embodiments of the present invention shown in the accompanying drawings and described according to the accompanying drawings are merely exemplary, and the present invention is not limited to these embodiments.

[0024] It should be noted that the same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0025] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0026] The embodiment of the present invention first provides a power supply circuit of a UPS power supply. Figure 1 and Figure 2 The power supply circuit mainly includes a first switch module 10, a second switch module 20 and a power diode D1.

[0027] The control end of the first switch module 10 is connected to the first control signal EN1, the first switch module 10 is controlled by the first control signal EN1 and is set to a normally open state, and the input end of the first switch module 10 receives a first input voltage V from the mains power supply end. i1 And output the first output voltage V from the output terminal o1 The control end of the second switch module 20 is connected to the second control signal EN2. The second switch module 20 is controlled by the second control signal EN2 and is set to a normally open state. The input end of the second switch module 20 receives a second input voltage V from the battery power supply end. i2 And output the second output voltage V o2 The anode of the power diode D1 is connected to the output end of the second switch module 20 , and the cathode is connected to the output end of the first switch module 10 and connected to the load power supply end.

[0028] Specifically, Figure 1 and Figure 2 As shown, the mains power supply end is provided with a mains power bus L1, the input end of the first switch module 10 is connected to the mains power bus L1, and the mains power bus L1 provides a first input voltage V i1The battery power supply end is provided with a battery power bus L2, and the input end of the second switch module 20 is connected to the battery power bus L2, and the battery power bus L2 provides a second input voltage V i2 The load power supply end is provided with a load power supply bus L3, and the load power supply bus L3 is connected to the cathode of the power diode D1 and the output end of the first switch module 10, so as to provide the output voltage to the load.

[0029] It should be noted that the first input voltage V i1 It is a DC voltage formed after the external mains electricity is rectified and filtered. The battery power bus L2 provides a second input voltage V i2 The DC output voltage is the DC voltage output by the battery. The DC output voltage received by the load power supply bus L3 is provided to the load after being processed by inversion, filtering, etc.

[0030] In the UPS power system, the voltage on the mains power bus L1 is also needed to charge the battery, so the voltage on the mains power bus L1 is usually greater than the output voltage of the battery, that is, the first input voltage V i1 is greater than the second input voltage V i2 In some commonly used UPS power supplies, the first input voltage V i1 is 7.2V, the second input voltage V i2 Correspondingly, the output terminal of the first switch module 10 outputs a first output voltage V o1 is also greater than the second output voltage V outputted by the output terminal of the second switch module 20 o2 .

[0031] The power supply circuit as described above:

[0032] (1) When the mains power supply end is supplying power normally: the first switch module 10 in the normally open state receives the first input voltage V i1 And output the first output voltage V o1 , the first output voltage V o1 The second switch module 20 in the normally open state receives the second input voltage V i2 And output the second output voltage V o2 , the second output voltage V o2 Connected to the anode of the power diode D1. Since the first output voltage V o1 Greater than the second output voltage V o2 , the power diode D1 is turned off, and the first output voltage V output by the first switch module 10 is o1Connected to the load power supply bus L3 to supply power to the load.

[0033] (2) When the mains power supply terminal is abnormal and cannot supply power normally, that is, the first input voltage V i1 Loss of voltage, the first output voltage V o1 The voltage is also lost accordingly and is less than the second output voltage V o2 , the power diode D1 is turned on, and the second output voltage V output by the second switch module 20 is o2 The load is powered by the power diode D1 connected to the load power supply bus L3.

[0034] Therefore, in the power supply circuit described in the above embodiment, when the AC input fails and the voltage is lost, it is necessary to switch from the AC power supply mode to the battery power supply mode, without waiting for the control signal formed and sent by the main control chip based on real-time monitoring of the AC power state, the battery power supply can be immediately and automatically connected to the load power supply end, which greatly reduces the delay time of switching from AC power supply to battery power supply in the UPS power supply, and improves the performance of the UPS power supply. Without considering the conduction time of the power diode D1, the switching delay time is close to 0ms, which can be understood as zero delay.

[0035] It should be noted that the first control signal EN1 and the second control signal EN2 are both provided by the main control chip MCU 40. Further, when the main control chip MCU 40 detects that the main power supply end is abnormal and cannot supply power normally, the first control signal EN1 controls the first switch module 10 to turn off, and its input end is disconnected from the output end.

[0036] In a specific embodiment, Figure 2 As shown, the first switch module 10 includes a first MOS switch tube Q1, the source of the first MOS switch tube Q1 is connected to the mains power bus L1 as an input end, and receives the first input voltage V i1 The drain of the first MOS switch tube Q1 is used as an output terminal, connected to the load power supply bus L3 and the cathode of the power diode D1, and outputs the first output voltage V o1 The gate of the first MOS switch tube Q1 is controlled by the first control signal EN1 so that the first MOS switch tube Q1 is in a normally-on state.

[0037] More specifically, in this embodiment, if Figure 2As shown, the first switch module 10 further includes a second MOS switch tube Q2, the first MOS switch tube Q1 is a PMOS tube, and the second MOS switch tube Q2 is an NMOS tube. A first resistor R1 and a first capacitor C1 are connected in parallel between the source and the gate of the first MOS switch tube Q1, the source of the second MOS switch tube Q2 is connected to the ground, the drain of the second MOS switch tube Q2 is connected to the gate of the first MOS switch tube Q1 through the second resistor R2, and the gate of the second MOS switch tube Q2 receives the first control signal EN1 provided by the main control chip MCU 40.

[0038] The first switch module 10 as described above: when the mains power supply end normally supplies power to provide the first input voltage V i1 When the main control chip MCU 40 provides the first control signal EN1 of high level, the NMOS tube Q2 is turned on, and the first input voltage V received by the source of the PMOS tube Q1 is i1 The voltage is divided by the first resistor R1 and the second resistor R2 and connected to the gate, which lowers the gate voltage. The PMOS tube Q1 is turned on, and the drain of the PMOS tube Q1 outputs the first output voltage V o1 When the main control chip MCU 40 detects that the mains power supply end is abnormal and cannot supply power normally, it provides the first control signal EN1 of low level, the NMOS tube Q2 is turned off, the PMOS tube Q1 is also turned off, and the input end and the output end of the first switch module 10 are disconnected. Therefore, in the first switch module 10 of this specific circuit, the first control signal EN1 is high level, and the first switch module 10 is set to a normally open state.

[0039] In a specific embodiment, Figure 2 As shown, the second switch module 20 includes a third MOS switch tube Q3, the source of the third MOS switch tube Q3 is connected to the battery power bus L2 as an input end, and receives the second input voltage V i2 The drain of the third MOS switch tube Q3 is used as an output terminal, connected to the anode of the power diode D1, and outputs the second output voltage V o2 The gate of the third MOS switch tube Q3 is controlled by the second control signal EN2 so that the third MOS switch tube Q3 is in a normally-on state.

[0040] More specifically, in this embodiment, if Figure 2As shown, the second switch module 20 further includes a fourth MOS switch tube Q4, the third MOS switch tube Q3 is a PMOS tube, and the fourth MOS switch tube Q4 is an NMOS tube. Among them, a third resistor R3 and a second capacitor C2 are connected in parallel between the source and the gate of the third MOS switch tube Q3, the source of the fourth MOS switch tube Q4 is connected to the ground, the drain of the fourth MOS switch tube Q4 is connected to the gate of the third MOS switch tube Q3 through the fourth resistor R4, and the gate of the fourth MOS switch tube Q4 receives the second control signal EN2 provided by the main control chip MCU 40.

[0041] The second switch module 20 as described above: when the battery power supply end is normally powered to provide the second input voltage V i2 When the main control chip MCU 40 provides the second control signal EN2 of high level, the NMOS tube Q4 is turned on, and the source of the PMOS tube Q3 receives the second input voltage V i2 The third resistor R3 and the fourth resistor R4 divide the voltage and connect it to the gate, pulling down the gate voltage, turning on the PMOS tube Q3, and the drain of the PMOS tube Q3 outputs the second output voltage V o2 When the main control chip MCU 40 detects that the battery power supply end is abnormal and cannot supply power normally, it provides the second control signal EN2 of low level, the NMOS tube Q4 is turned off, the PMOS tube Q3 is also turned off, and the input end and the output end of the second switch module 20 are disconnected. Therefore, in the second switch module 20 of this specific circuit, the second control signal EN2 is high level, and the second switch module 20 is set to a normally open state.

[0042] As a preferred solution, the power diode D1 is selected as a high-current Schottky diode, which has the advantages of fast response speed, small forward voltage drop and good reverse blocking performance.

[0043] As a preferred solution, in this embodiment, Figure 1 and Figure 2 As shown, the power supply circuit also includes a third switch module 30, which is controlled by a third control signal EN3 and is set to a normally closed state. The input end of the third switch module 30 is connected to the output end of the second switch module 20, and the output end of the third switch module 30 is connected to the cathode of the power diode D1 and connected to the load power supply end. When the mains power supply end cannot supply power normally and the power diode D1 is turned on, the third control signal EN3 controls the third switch module 30 to be in an open state. Among them, the third control signal EN3 is provided by the main control chip MCU 40.

[0044] As described above, the power supply circuit provided by the embodiment of the present invention uses the power diode D1 to automatically switch the second output voltage V output by the second switch module 20 to the power supply circuit when the mains power supply end fails to supply power normally. o2 Connected to the load power supply end for power supply. Since the power diode D1 is easy to heat up and has a relatively large internal resistance, it is not conducive to being connected to the power supply circuit for a long time. Therefore, the third switch module 30 is set at the output end and the load power supply end of the second switch module 20. The third switch module 30 is set to a normally closed state. When the mains power supply end cannot supply power normally and the power diode D1 is turned on, the third control signal EN3 controls the third switch module 30 to be turned on. At this time, the second output voltage V output by the second switch module 20 is o2 The third switch module 30 is connected to the load power supply terminal for power supply. It should be noted that, in the third switch module 30, the components connected to the power supply circuit should be selected to have lower heat generation and smaller internal resistance than the power diode D1.

[0045] In a specific embodiment, Figure 2 As shown, the third switch module 30 includes a fifth MOS switch tube Q5, the drain of which is connected to the output end of the second switch module 10 as an input end to receive the second output voltage V o2 The source of the fifth MOS switch tube Q5 is connected to the cathode of the power diode D1 as an output terminal and connected to the load power supply bus L3. The gate of the fifth MOS switch tube Q5 is controlled by the third control signal EN3 so that the fifth MOS switch tube Q5 is in a normally off state.

[0046] More specifically, in this embodiment, if Figure 2 As shown, the third switch module 30 further includes a sixth MOS switch tube Q6, the fifth MOS switch tube Q5 is a PMOS tube, and the sixth MOS switch tube Q6 is an NMOS tube. A fifth resistor R5 and a third capacitor C3 are connected in parallel between the source and the gate of the fifth MOS switch tube Q5, the source of the sixth MOS switch tube Q6 is connected to the ground, the drain of the sixth MOS switch tube Q6 is connected to the gate of the fifth MOS switch tube Q5 through the sixth resistor R6, and the gate of the sixth MOS switch tube Q6 receives the third control signal EN3 provided by the main control chip MCU 40.

[0047] The third switch module 30 as described above: when the mains power supply end is supplying power normally, the main control chip MCU 40 provides the third control signal EN3 of low level, the NMOS tube Q6 is turned off, the PMOS tube Q5 is also turned off, and the input end and the output end of the third switch module 30 are disconnected. When the mains power supply end cannot supply power normally and the power diode D1 is turned on, the main control chip MCU40 provides the third control signal EN3 of high level, the NMOS tube Q6 is turned on, the voltage of the negative electrode of the power diode D1 connected to the source of the PMOS tube Q5 is divided by the fifth resistor R5 and the sixth resistor R6 and connected to the gate, the gate voltage is pulled down, the PMOS tube Q5 is turned on, and the drain of the PMOS tube Q5 is connected to the second output voltage V o2 Through the source output, it is connected to the load power supply end for power supply. Therefore, in the third switch module 30 of this specific circuit, the third control signal EN3 is at a low level, and the third switch module 30 is set to a normally closed state. When the third switch module 30 needs to be turned on, the third control signal EN3 is controlled to be set to a high level. Among them, in the third switch module 30, the component connected to the power supply circuit is the PMOS tube Q5, which has lower heat generation and smaller internal resistance than the power diode D1.

[0048] Furthermore, the power supply circuit of the UPS power supply in this embodiment, in addition to supplying power to the load, also needs to provide working voltage to some functional units of the UPS power supply itself, such as the main control chip MCU, display unit, communication unit and other functional units.

[0049] As a specific example, in this embodiment, Figure 2 As shown, the power supply circuit also includes an MCU power supply module 50, an LCD power supply module 60 and a BLUE power supply module 70. Among them, the MCU power supply module 50 is used to convert the voltage provided by the mains power supply end, the battery power supply end, or the photovoltaic power supply, etc., into a 3.3V working voltage and provide it to the main control chip MCU 40 to drive the main control chip MCU 40; the LCD power supply module 60 is used to convert the voltage provided by the mains power supply end, the battery power supply end, or the photovoltaic power supply end, etc., into a 3.3V working voltage and provide it to the LCD display unit to drive the LCD display unit; the BLUE power supply module 70 is used to convert the voltage provided by the mains power supply end, the battery power supply end, or the photovoltaic power supply end, etc., into a 3.3V working voltage and provide it to the Bluetooth communication unit to obtain the Bluetooth communication unit. The specific circuits of the power supply modules of these functional units can be realized by referring to the existing technology, and will not be described in detail here.

[0050] Based on the power supply circuit provided in the above embodiment, this embodiment also provides a UPS power supply including the power supply circuit as described above, and the UPS power supply also includes a mains input terminal, a rectifier, an inverter, a battery, a main control chip MCU, a charging management unit, a battery management unit, an LCD display unit, and a Bluetooth communication unit, etc. The UPS power supply uses the power supply circuit provided in the above embodiment of the present invention to supply power to the load.

[0051] To summarize, in the UPS power supply and its power supply circuit provided by the embodiments of the present invention, when the AC input fails and the voltage is lost, and it is necessary to switch from the AC power supply mode to the battery power supply mode, there is no need to wait for the control signal generated and sent by the main control chip based on real-time monitoring of the AC power status. The battery power supply can be immediately and automatically connected to the load power supply end, which greatly reduces the delay time of switching from AC power supply to battery power supply in the UPS power supply and improves the performance of the UPS power supply.

[0052] The above is only a specific implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A power supply circuit of a UPS power supply, characterized in that: include: A first switch module, controlled by a first control signal and set to a normally open state; The input end of the first switch module receives a first input voltage from the mains power supply end and outputs a first output voltage from the output end; A second switch module, controlled by a second control signal and set to a normally open state; the input end of the second switch module receives a second input voltage from the battery power supply end and outputs a second output voltage from the output end; A power diode, wherein the anode of the power diode is connected to the output end of the second switch module, and the cathode of the power diode is connected to the output end of the first switch module and to the load power supply end.

2. The power supply circuit according to claim 1, characterized in that: The first switch module includes a first MOS switch tube, a source of the first MOS switch tube serves as an input end to receive the first input voltage, a drain of the first MOS switch tube serves as an output end to output the first output voltage, and a gate of the first MOS switch tube is controlled by the first control signal so that the first MOS switch tube is in a normally open state.

3. The power supply circuit according to claim 2, characterized in that: The first switch module also includes a second MOS switch tube, the first MOS switch tube is a PMOS tube, and the second MOS switch tube is an NMOS tube; wherein a first resistor and a first capacitor are connected in parallel between the source and the gate of the first MOS switch tube, the source of the second MOS switch tube is connected to the ground, the drain of the second MOS switch tube is connected to the gate of the first MOS switch tube through a second resistor, and the gate of the second MOS switch tube receives the first control signal provided by the main control chip.

4. The power supply circuit according to claim 1, characterized in that: The second switch module includes a third MOS switch tube, the source of the third MOS switch tube serves as an input end to receive the second input voltage, the drain of the third MOS switch tube serves as an output end to output the second output voltage, and the gate of the third MOS switch tube is controlled by the second control signal so that the third MOS switch tube is in a normally open state.

5. The power supply circuit according to claim 4, characterized in that: The second switch module also includes a fourth MOS switch tube, the third MOS switch tube is a PMOS tube, and the fourth MOS switch tube is an NMOS tube; wherein a third resistor and a second capacitor are connected in parallel between the source and the gate of the third MOS switch tube, the source of the fourth MOS switch tube is connected to the ground, the drain of the fourth MOS switch tube is connected to the gate of the third MOS switch tube through a fourth resistor, and the gate of the fourth MOS switch tube receives the second control signal provided by the main control chip.

6. The power supply circuit according to claim 1, characterized in that: The power diode is a high-current Schottky diode.

7. The power supply circuit according to any one of claims 1 to 6, characterized in that: The power supply circuit further includes a third switch module, which is controlled by a third control signal and is set to a normally closed state; an input end of the third switch module is connected to an output end of the second switch module, and an output end of the third switch module is connected to the cathode of the power diode and connected to a load power supply end; When the mains power supply end fails to supply power normally and the power diode is turned on, the third control signal controls the third switch module to be in an on state.

8. The power supply circuit according to claim 7, characterized in that: The third switch module includes a fifth MOS switch tube, the drain of the fifth MOS switch tube is connected to the output end of the second switch module as an input end, the source of the fifth MOS switch tube is connected to the negative electrode of the power diode as an output end and connected to the load power supply end, and the gate of the fifth MOS switch tube is controlled by the third control signal so that the fifth MOS switch tube is in a normally off state.

9. The power supply circuit according to claim 8, characterized in that: The third switch module also includes a sixth MOS switch tube, the fifth MOS switch tube is a PMOS tube, and the sixth MOS switch tube is an NMOS tube; wherein a fifth resistor and a third capacitor are connected in parallel between the source and the gate of the fifth MOS switch tube, the source of the sixth MOS switch tube is connected to the ground, the drain of the sixth MOS switch tube is connected to the gate of the fifth MOS switch tube through the sixth resistor, and the gate of the sixth MOS switch tube receives the third control signal provided by the main control chip.

10. A UPS power supply, characterized in that: Comprising the power supply circuit as described in any one of claims 1-9.

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