Power supply device with protection circuit

Abstract

The present disclosure provides a power supply device with a protection circuit, comprising a power module, a power output terminal, a converter module, a bus capacitor and a protection circuit. The power module receives an input power supply. The converter module, the protection circuit and the bus capacitor are electrically connected between the power module and the power output terminal. The protection circuit architecture is used to implement overvoltage protection when the input power supply is overvoltage, and to suppress surge current when the power supply device is turned on, and to adjust the voltage of the bus capacitor under overvoltage and undervoltage conditions.

Description

Technical Field

[0001] The present disclosure relates to a power supply device with a protection circuit, and in particular to a power supply device which realizes overvoltage and overcurrent protection with fewer power devices. Background Art

[0002] According to the IEC (International Electrotechnical Commission) standard, low-voltage electrical devices need to be protected against voltage interference and electromagnetic interference. This requires that in specific applications, the power supply must not be damaged within a specific period of time when subjected to abnormal overvoltage. For this reason, additional protection circuits must be set up accordingly. Existing protection circuits are mainly designed based on cutting off the input voltage or building a busbar discharge branch. However, they use more power devices and complex circuits, which are more expensive.

[0003] Therefore, how to develop a protection circuit that can improve the above-mentioned prior art is an urgent need. Summary of the invention

[0004] The purpose of the present disclosure is to provide a power supply device with a protection circuit, which realizes overvoltage protection with fewer power devices by integrating and reusing power devices, suppresses surge current when the power supply device is turned on, and regulates the voltage of the bus capacitor under overvoltage and undervoltage conditions, effectively reducing circuit complexity and cost, while improving the power density of the power supply.

[0005] To achieve the above-mentioned purpose, the present disclosure provides a power supply device with a protection circuit, comprising a power supply module, a power supply output terminal, a converter module, a bus capacitor and a protection circuit. The power supply module receives input power and has a first end and a second end. The converter module is electrically connected between the power supply module and the power supply output terminal. The bus capacitor is electrically connected between the second end of the power supply module and the power supply output terminal. The protection circuit comprises a protection switch, a first diode, a second diode, a resistor, a third diode and a switch tube. The protection switch is electrically connected between the first end of the power supply module and the converter module, the anode of the first diode is electrically connected to the first end of the power supply module, the cathode of the first diode is electrically connected to the cathode of the second diode and one end of the resistor, the anode of the second diode is electrically connected to the cathode of the third diode and the power supply output terminal, the anode of the third diode is electrically connected to the other end of the resistor and one end of the switch tube, and the other end of the switch tube is electrically connected to the second end of the power supply module.

[0006] To achieve the above-mentioned purpose, the present disclosure further provides a power supply device with a protection circuit, comprising a power module, a power output terminal, a converter module, a bus capacitor and a protection circuit. The power module receives input power and has a first terminal and a second terminal. The converter module comprises an inductor, a boost diode and a switch tube, wherein the cathode of the boost diode is electrically connected to the power output terminal, the anode of the boost diode is electrically connected to one end of the inductor and the switch tube, and the other end of the switch tube is electrically connected to the second end of the power module. The bus capacitor is electrically connected between the second end of the power module and the power output terminal. The protection circuit comprises a protection switch, a first diode, a second diode and a resistor, wherein the protection switch has a common terminal, a first contact terminal and a second contact terminal. The anode of the first diode is electrically connected to the first end of the power module and the first contact terminal of the protection switch, the cathode of the first diode is electrically connected to the cathode of the second diode and one end of the resistor, the other end of the resistor is electrically connected to the second contact terminal of the protection switch, the common end of the protection switch is electrically connected to the inductor of the converter module, and the anode of the second diode is electrically connected to the power output terminal.

[0007] To achieve the above-mentioned purpose, the present disclosure further provides a power supply device with a protection circuit, comprising a power supply module, a power supply output terminal, a converter module, a bus capacitor and a protection circuit. The power supply module receives input power and has a first end and a second end. The converter module is electrically connected between the power supply module and the power supply output terminal. The bus capacitor is electrically connected between the second end of the power supply module and the power supply output terminal. The protection circuit comprises a protection switch, a first diode, a first resistor, a second diode, a third diode, a second resistor and a switch tube. The protection switch is electrically connected between the first end of the power supply module and the converter module, the anode of the first diode is electrically connected to the first end of the power supply module, the cathode of the first diode is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to the anode of the second diode and the anode of the third diode, one end of the second resistor is electrically connected to the cathode of the second diode, the other end of the second resistor is electrically connected to the cathode of the third diode and one end of the switch tube, and the other end of the switch tube is electrically connected to the second end of the power supply module.

[0008] To achieve the above-mentioned purpose, the present disclosure further provides a power supply device with a protection circuit, comprising a power supply module, a power supply output terminal, a converter module, a bus capacitor and a protection circuit. The power supply module receives input power and has a first end and a second end. The converter module is electrically connected between the power supply module and the power supply output terminal. The bus capacitor is electrically connected between the second end of the power supply module and the power supply output terminal. The protection circuit comprises a protection switch, a first diode, a first resistor, a second resistor and a switch tube. The protection switch is electrically connected between the first end of the power supply module and the converter module, the anode of the first diode is electrically connected to the first end of the power supply module, the cathode of the first diode is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to one end of the second resistor and one end of the switch tube, the other end of the second resistor is electrically connected to the power supply output terminal, and the other end of the switch tube is electrically connected to the second end of the power supply module. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic diagram of the circuit structure of a power supply device with a protection circuit according to the first preferred embodiment of the present disclosure.

[0010] Figure 2 It is a circuit structure schematic diagram of a power supply device with a protection circuit according to a second preferred embodiment of the present disclosure.

[0011] Figure 3 It is a schematic diagram of the circuit structure of a power supply device with a protection circuit according to the third preferred embodiment of the present disclosure.

[0012] Figure 4 Schematic diagram of the circuit structure of a power supply device with a protection circuit according to the fourth preferred embodiment of the present disclosure.

[0013] Figure 5 Show Figure 1 A circuit variation of the first embodiment.

[0014] Figure 6 A bridgeless PFC circuit of a converter module in an embodiment of the present disclosure is shown.

[0015] Figure 7 A bridgeless PFC circuit of a converter module in an embodiment of the present disclosure is shown.

[0016] Description of reference numerals:

[0017] 1, 2, 3, 4: Power supply device with protection circuit

[0018] 10: Power module

[0019] 10a: First end

[0020] 10b: Second end

[0021] Po: power output terminal

[0022] C1: busbar capacitor

[0023] Vac: Input power

[0024] L1: Inductor

[0025] D1: Boost diode

[0026] D2: diode

[0027] Q1, Q11, Q31, Q41: switch tube

[0028] S1, S2, S3, S4: protection switch

[0029] A: First contact end

[0030] B: Second contact end

[0031] C: Public terminal

[0032] D11, D21, D31, D41: first diode

[0033] D12, D22, D32: Second diode

[0034] D13, D33: The third diode

[0035] R11, R21: resistors

[0036] R31, R41: first resistor

[0037] R32, R42: Second resistor DETAILED DESCRIPTION

[0038] Some typical embodiments that embody the features and advantages of the present disclosure will be described in detail in the following description. It should be understood that the present disclosure can have various changes in different implementations without departing from the scope of the present disclosure, and the descriptions and illustrations therein are essentially for illustrative purposes, rather than for limiting the present disclosure.

[0039] Figure 1 FIG. 1 is a schematic diagram of the circuit structure of a power supply device with a protection circuit according to the first preferred embodiment of the present disclosure. Figure 1As shown, the power supply device 1 with a protection circuit includes a power module 10, a power output terminal Po, a converter module, a bus capacitor C1 and a protection circuit. The power module 10 receives an input power supply Vac, and the power module 10 has a first terminal 10a and a second terminal 10b. The converter module includes an inductor L1, a boost diode D1 and a switch tube Q1, wherein the cathode of the boost diode D1 is electrically connected to the power output terminal Po, the anode of the boost diode D1 is electrically connected to the inductor L1 and one end of the switch tube Q1, and the other end of the switch tube Q1 is electrically connected to the second end 10b of the power module 10. The bus capacitor C1 is electrically connected between the second end 10b of the power module 10 and the power output terminal Po. The protection circuit includes a protection switch S1, a first diode D11, a second diode D12, a resistor R11, a third diode D13 and a switch tube Q11. The protection switch S1 is electrically connected between the first end 10a of the power module 10 and the converter module, the anode of the first diode D11 is electrically connected to the first end 10a of the power module 10, the cathode of the first diode D11 is electrically connected to the cathode of the second diode D12 and one end of the resistor R11, the anode of the second diode D12 is electrically connected to the cathode of the third diode D13 and the power output end Po, the anode of the third diode D13 is electrically connected to the other end of the resistor R11 and one end of the switch tube Q11, and the other end of the switch tube Q11 is electrically connected to the second end 10b of the power module 10.

[0040] When the input power Vac is lower than the preset value, it is determined that the input power Vac is within the normal range. In this case, when the circuit is initially turned on, the protection switch S1 is turned off to suppress the surge current generated during startup using the resistor R11. When the surge current disappears, the protection switch S1 is controlled to be turned on to allow the converter module to work normally.

[0041] On the contrary, when the input power Vac is higher than the preset value, it is determined that the input power Vac is over-voltage. In this case, the protection circuit operates alternately in two working modes. First, when the input power Vac is detected to be over-voltage and the protection switch S1 is controlled to be turned off, since it takes a certain time to detect the input power Vac, and there is also a delay in controlling the protection switch S1 to be turned off, the bus capacitor C1 is already in an over-voltage state (that is, the voltage on the bus capacitor C1 is higher than the first preset value). Therefore, the protection circuit operates in the first working mode, turning on the switch tube Q11, so that the second diode D12, the resistor R11, the switch tube Q11 and the bus capacitor C1 form a discharge circuit, and discharge the bus capacitor C1 through the discharge circuit, thereby reducing the voltage on the bus capacitor C1. After a period of discharge, if the voltage on the bus capacitor C1 drops below the set second preset value, the protection circuit operates in the second working mode, and the switch tube Q11 is turned off, so that the power module 10, the first diode D11, the resistor R11, the third diode D13 and the bus capacitor C1 form a charging circuit, so that the input power Vac charges the bus capacitor C1 through the charging circuit, thereby increasing the voltage on the bus capacitor C1. When the voltage on the bus capacitor C1 is increased to higher than the first preset value and is in an overvoltage state, the protection circuit switches to the first working mode again, and repeats this process, so that the voltage on the bus capacitor C1 can be continuously controlled and adjusted while the overvoltage protection of the input power Vac is realized.

[0042] Thus, the power supply device 1 with the protection circuit can achieve surge current suppression and overvoltage protection with fewer power devices, effectively reducing circuit complexity and cost, while increasing the power density of the power supply. Furthermore, when performing overvoltage protection, the voltage on the bus capacitor C1 can still be continuously regulated.

[0043] Figure 2 FIG. 1 is a schematic diagram of the circuit structure of a power supply device with a protection circuit according to a second preferred embodiment of the present disclosure. Figure 2 As shown, the power supply device 2 with a protection circuit includes a power module 10, a power output terminal Po, a converter module, a bus capacitor C1 and a protection circuit. The power module 10 receives an input power supply Vac, and the power module 10 has a first terminal 10a and a second terminal 10b. The components and connection relationship in the converter module are similar to Figure 1The converter module of the first preferred embodiment shown is the same and will not be described again here. The bus capacitor C1 is electrically connected between the second end 10b of the power module 10 and the power output terminal Po. The protection circuit includes a protection switch S2, a first diode D21, a second diode D22 and a resistor R21. The protection switch S2 has a common terminal C, a first contact terminal A and a second contact terminal B, the anode of the first diode D21 is electrically connected to the first end 10a of the power module 10 and the first contact terminal A of the protection switch S2, the cathode of the first diode D21 is electrically connected to the cathode of the second diode D22 and one end of the resistor R21, the other end of the resistor R21 is electrically connected to the second contact terminal B of the protection switch S2, the common terminal C of the protection switch S2 is electrically connected to the inductor L1 of the converter module, and the anode of the second diode D22 is electrically connected to the power output terminal Po.

[0044] When the input power Vac is lower than the preset value, it is determined that the input power Vac is within the normal range. In this case, when the circuit is initially turned on, the common terminal C of the protection switch S2 is connected to the second contact terminal B, so that the surge current generated during the startup is suppressed by the resistor R21. When the surge current disappears, the common terminal C of the protection switch S2 is controlled to be connected to the first contact terminal A, so that the converter module can work normally.

[0045] On the contrary, when the input power Vac is higher than the preset value, it is determined that the input power Vac is over-voltage. In this case, the protection circuit operates alternately in two working modes. First, when the input power Vac is detected to be over-voltage and the common terminal C of the protection switch S2 is controlled to be connected to the second contact terminal B, since it takes a certain time to detect the input power Vac and there is also a time delay in controlling the protection switch S2, the bus capacitor C1 is already in an over-voltage state (that is, the voltage on the bus capacitor C1 is higher than the first preset value). Therefore, the protection circuit operates in the first working mode, turning on the switch tube Q1 so that the second diode D22, the resistor R21, the inductor L1, the switch tube Q1 and the bus capacitor C1 form a discharge circuit, and discharge the bus capacitor C1 through the discharge circuit, thereby reducing the voltage on the bus capacitor C1. After a period of discharge, if the voltage on the bus capacitor C1 drops below the set second preset value, the protection circuit operates in the second working mode, and the switch tube Q1 is turned off, so that the power module 10, the first diode D21, the resistor R21, the inductor L1, the boost diode D1 and the bus capacitor C1 form a charging circuit, so that the input power Vac charges the bus capacitor C1 through the charging circuit, thereby increasing the voltage on the bus capacitor C1. When the voltage on the bus capacitor C1 is increased to higher than the first preset value and is in an overvoltage state, the protection circuit switches to the first working mode again, and repeats this process, so that the overvoltage protection of the input power Vac can be achieved while continuing to control and adjust the voltage on the bus capacitor C1.

[0046] Thus, the power supply device 2 with protection circuit can realize surge current suppression and overvoltage protection with fewer power devices, effectively reducing circuit complexity and cost, while improving the power density of the power supply. Furthermore, when performing overvoltage protection, the voltage on the bus capacitor C1 can still be continuously regulated.

[0047] Figure 3 FIG. 1 is a schematic diagram of the circuit structure of a power supply device with a protection circuit according to a third preferred embodiment of the present disclosure. Figure 3 As shown, the power supply device 3 with protection circuit includes a power module 10, a power output terminal Po, a converter module, a bus capacitor C1 and a protection circuit. The power module 10 receives the input power Vac, and the power module 10 has a first terminal 10a and a second terminal 10b. The components and connection relationship in the converter module are similar to Figure 1 The converter module of the first preferred embodiment shown is the same and will not be described again. The bus capacitor C1 is electrically connected between the second end 10b of the power module 10 and the power output terminal Po. The protection circuit includes a protection switch S3, a first diode D31, a first resistor R31, a second diode D32, a third diode D33, a second resistor R32 and a switch tube Q31. The protection switch S3 is electrically connected between the first end 10a of the power module 10 and the converter module, the anode of the first diode D31 is electrically connected to the first end 10a of the power module 10, the cathode of the first diode D31 is electrically connected to one end of the first resistor R31, the other end of the first resistor R31 is electrically connected to the anode of the second diode D32 and the anode of the third diode D33, one end of the second resistor R32 is electrically connected to the cathode of the second diode D32, the other end of the second resistor R32 is electrically connected to the cathode of the third diode D33 and one end of the switch tube Q31, and the other end of the switch tube Q31 is electrically connected to the second end 10b of the power module 10.

[0048] In other embodiments, the first diode D31 and the third diode D33 may be provided selectively or simultaneously. Specifically, when the first diode D31 is provided, the branch where the third diode D33 is located may be replaced with a wire, and vice versa, when the third diode D33 is provided, the branch where the first diode D31 is located may be replaced with a wire, or both the first diode D31 and the third diode D33 may be provided. Figure 3 The above implementations can all achieve surge current suppression and overvoltage protection through the control method described below, effectively reducing circuit complexity and cost, while improving the technical effect of the power density of the power supply.

[0049] When the input power Vac is lower than the preset value, it is determined that the input power Vac is within the normal range. In this case, when the circuit is initially turned on, the protection switch S3 is turned off to suppress the surge current generated during startup using the first resistor R31. When the surge current disappears, the protection switch S3 is controlled to be turned on to allow the converter module to work normally.

[0050] On the contrary, when the input power Vac is higher than the preset value, it is determined that the input power Vac is over-voltage. In this case, the protection circuit operates alternately in two working modes. First, when the input power Vac is detected to be over-voltage and the protection switch S3 is controlled to be turned off, since it takes a certain time to detect the input power Vac, and there is also a delay in controlling the protection switch S3 to be turned off, the bus capacitor C1 is already in an over-voltage state (that is, the voltage on the bus capacitor C1 is higher than the first preset value). Therefore, the protection circuit operates in the first working mode, and the switch tube Q31 is turned on, so that the second resistor R32, the switch tube Q31 and the bus capacitor C1 form a discharge circuit, and the bus capacitor C1 is discharged through the discharge circuit, thereby reducing the voltage on the bus capacitor C1. After a period of discharge, if the voltage on the bus capacitor C1 drops below the set second preset value, the protection circuit operates in the second working mode, and the switch tube Q31 is turned off, so that the power module 10, the first diode D31, the first resistor R31, the second diode D32 and the bus capacitor C1 form a charging circuit, so that the input power Vac charges the bus capacitor C1 through the charging circuit, thereby increasing the voltage on the bus capacitor C1. When the voltage on the bus capacitor C1 is increased to higher than the first preset value and is in an overvoltage state, the protection circuit switches to the first working mode again, and repeats this process, so that the overvoltage protection of the input power Vac can be achieved while continuing to control and adjust the voltage on the bus capacitor C1.

[0051] Thus, the power supply device 3 with protection circuit can realize surge current suppression and overvoltage protection with fewer power devices, effectively reducing circuit complexity and cost, while improving the power density of the power supply. Furthermore, when performing overvoltage protection, the voltage on the bus capacitor C1 can still be continuously regulated.

[0052] Figure 4 FIG. 4 is a schematic diagram of the circuit structure of a power supply device with a protection circuit according to a fourth preferred embodiment of the present disclosure. Figure 4 As shown, the power supply device 4 with a protection circuit includes a power module 10, a power output terminal Po, a converter module, a bus capacitor C1 and a protection circuit. The power module 10 receives an input power supply Vac, and the power module 10 has a first terminal 10a and a second terminal 10b. The components and connection relationship in the converter module are similar to Figure 1The converter module of the first preferred embodiment shown is the same and will not be described again. The bus capacitor C1 is electrically connected between the second end 10b of the power module 10 and the power output terminal Po. The protection circuit includes a protection switch S4, a first diode D41, a first resistor R41, a second resistor R42 and a switch tube Q41. The protection switch S4 is electrically connected between the first end 10a of the power module 10 and the converter module, the anode of the first diode D41 is electrically connected to the first end 10a of the power module 10, the cathode of the first diode D41 is electrically connected to one end of the first resistor R41, the other end of the first resistor R41 is electrically connected to one end of the second resistor R42 and one end of the switch tube Q41, the other end of the second resistor R42 is electrically connected to the power output terminal Po, and the other end of the switch tube Q41 is electrically connected to the second end 10b of the power module 10.

[0053] When the input power Vac is lower than the preset value, it is determined that the input power Vac is within the normal range. In this case, when the circuit is initially turned on, the protection switch S4 is turned off to suppress the surge current generated during startup using the first resistor R41 and the second resistor R42. When the surge current disappears, the protection switch S4 is controlled to be turned on to allow the converter module to work normally.

[0054] On the contrary, when the input power Vac is higher than the preset value, it is determined that the input power Vac is over-voltage. In this case, the protection circuit operates alternately in two working modes. First, when the input power Vac is detected to be over-voltage and the protection switch S4 is controlled to be turned off, since it takes a certain time to detect the input power Vac, and there is also a delay in controlling the protection switch S4 to be turned off, the bus capacitor C1 is already in an over-voltage state (that is, the voltage on the bus capacitor C1 is higher than the first preset value). Therefore, the protection circuit operates in the first working mode, turning on the switch tube Q41, so that the second resistor R42, the switch tube Q41 and the bus capacitor C1 form a discharge loop, and the bus capacitor C1 is discharged through the discharge loop, thereby reducing the voltage on the bus capacitor C1. After a period of discharge, if the voltage on the bus capacitor C1 drops below the set second preset value, the protection circuit operates in the second working mode, and the switch tube Q41 is turned off, so that the power module 10, the first diode D41, the first resistor R41, the second resistor R42 and the bus capacitor C1 form a charging circuit, so that the input power Vac charges the bus capacitor C1 through the charging circuit, thereby increasing the voltage on the bus capacitor C1. When the voltage on the bus capacitor C1 is increased to higher than the first preset value and is in an overvoltage state, the protection circuit switches to the first working mode again, and so on repeatedly, while achieving overvoltage protection for the input power Vac, it can still continue to control and adjust the voltage on the bus capacitor C1.

[0055] Thus, the power supply device 4 with protection circuit can realize surge current suppression and overvoltage protection with fewer power devices, effectively reducing circuit complexity and cost, while improving the power density of the power supply. Furthermore, when performing overvoltage protection, the voltage on the bus capacitor C1 can still be continuously regulated.

[0056] In some embodiments, the aforementioned converter module further includes a diode D2 , wherein an anode of the diode D2 is electrically connected to the inductor L1 , and a cathode of the diode D2 is electrically connected to a cathode of the boost diode D1 .

[0057] The aforementioned resistors (R11, R21, R31, R32, R41, R42) are preferably positive temperature coefficient (PTC) thermistors, but are not limited thereto. In some embodiments, the charging or discharging speed of the bus capacitor C1 by the charging circuit or the discharging circuit can be adjusted by changing the resistance values ​​of the resistors (R11, R21, R31, R32, R41, R42).

[0058] In other embodiments, the first diodes D11, D21, D31, and D41 may also be connected to the input power supply Vac. Specifically, the anodes of the first diodes D11, D21, D31, and D41 are connected to one end of the input power supply Vac, and correspondingly, the protection switches S1, S2, S3, and S4 are connected between the anodes of the first diodes and the rectifier circuit. Figure 5 Shows Figure 1 The specific circuit changes of the first embodiment, of course, in Figure 2 , Figure 3 and Figure 4 In other embodiments, the positions of the first diode and the protection switch can be similarly deformed, and only adaptive modifications need to be made to the circuit structure. The specific implementation method is the existing technical means of those skilled in the art and will not be described in detail here.

[0059] In other embodiments, the control method for the voltage on the bus capacitor C1 is not limited to the control method described in the above embodiment. For example, loop compensation, such as a proportional integral link, can be added to the detection control loop to further stabilize the voltage on the bus capacitor C1. The loop compensation method is an existing technical means for those skilled in the art and will not be described in detail here.

[0060] In other embodiments, the converter module may also be implemented by other circuit topologies, such as Figure 6 The bridgeless PFC circuit shown, or Figure 7 The bridgeless PFC circuit shown in FIG. Alternatively, it may be an existing buck circuit. Figure 6 and Figure 7Only variation examples are given for the protection circuit of the first embodiment proposed in the present invention. For the implementation methods of the various converter modules mentioned above, the protection circuits provided in other embodiments only need to adaptively adjust the connection relationship of the components. The specific implementation methods are existing technical means for those skilled in the art and will not be described in detail here.

[0061] In summary, the present disclosure provides a power supply device with a protection circuit, which can achieve surge current suppression and overvoltage protection with fewer power devices, effectively reduce circuit complexity and cost, and improve the power density of the power supply. Furthermore, when the power supply device with a protection circuit performs overvoltage protection, the voltage on the bus capacitor can still be continuously regulated, and the bus capacitor can provide electrical energy to the auxiliary power supply terminal.

[0062] It should be noted that the above are only preferred embodiments for illustrating the present disclosure, and the present disclosure is not limited to the embodiments described. The scope of the present disclosure is determined by the claims. Moreover, the present disclosure may be modified in various ways by those skilled in the art, but all of them are within the scope of the claims.

Claims

1. A power supply device with a protection circuit, comprising: A power module receives input power and has a first end and a second end; Power supply output terminal; A converter module, electrically connected between the power module and the power output terminal; A bus capacitor, electrically connected between the second end of the power module and the power output end; as well as A protection circuit, comprising a protection switch, a first diode, a second diode, a resistor, a third diode and a switch tube, wherein the protection switch is electrically connected between the first end of the power module and the converter module, the anode of the first diode is electrically connected to the first end of the power module, the cathode of the first diode is electrically connected to the cathode of the second diode and one end of the resistor, the anode of the second diode is electrically connected to the cathode of the third diode and the power output end, the anode of the third diode is electrically connected to the other end of the resistor and one end of the switch tube, and the other end of the switch tube is electrically connected to the second end of the power module. When the voltage on the bus capacitor is higher than a first preset value, the protection switch is turned off, the switch tube is turned on, and the second diode, the resistor, the switch tube and the bus capacitor form a discharge loop to reduce the voltage on the bus capacitor. When the voltage on the bus capacitor is lower than a second preset value, the protection switch is turned off, the switch tube is turned off, and the power module, the first diode, the resistor, the third diode and the bus capacitor form a charging loop to increase the voltage on the bus capacitor.

2. A power supply device with a protection circuit as described in claim 1, wherein the rate of change of the voltage on the bus capacitor varies with the resistance value of the discharge circuit or the charging circuit.

3. A power supply device with a protection circuit, comprising: A power module receives input power and has a first end and a second end; Power supply output terminal; The converter module comprises an inductor, a boost diode and a switch tube, wherein the cathode of the boost diode is electrically connected to the power output end, the anode of the boost diode is electrically connected to the inductor and one end of the switch tube, and the other end of the switch tube is electrically connected to the second end of the power module; a bus capacitor, electrically connected between the second end of the power module and the power output end; and A protection circuit comprises a protection switch, a first diode, a second diode and a resistor, wherein the protection switch has a common terminal, a first contact terminal and a second contact terminal, an anode of the first diode is electrically connected to the first terminal of the power module and the first contact terminal of the protection switch, a cathode of the first diode is electrically connected to the cathode of the second diode and one end of the resistor, the other end of the resistor is electrically connected to the second contact terminal of the protection switch, the common terminal of the protection switch is electrically connected to the inductor of the converter module, and an anode of the second diode is electrically connected to the power output terminal. When the voltage on the bus capacitor is higher than a first preset value, the common end of the protection switch is connected to the second contact end, the switch tube is turned on, and the second diode, the resistor, the inductor, the switch tube and the bus capacitor form a discharge loop to reduce the voltage on the bus capacitor. When the voltage on the bus capacitor is lower than a second preset value, the common end of the protection switch is connected to the second contact end, the switch tube is turned off, and the power module, the first diode, the resistor, the inductor, the boost diode and the bus capacitor form a charging circuit to increase the voltage on the bus capacitor.

4. The power supply device with a protection circuit as claimed in claim 3, wherein the rate of change of the voltage on the bus capacitor varies with the resistance of the discharge circuit or the charging circuit.

5. A power supply device with a protection circuit, comprising: A power module receives input power and has a first end and a second end; Power output terminal; A converter module, electrically connected between the power module and the power output terminal; A bus capacitor, electrically connected between the second end of the power module and the power output end; as well as A protection circuit, comprising a protection switch, a first diode, a first resistor, a second diode, a third diode, a second resistor and a switch tube, wherein the protection switch is electrically connected between the first end of the power module and the converter module, the anode of the first diode is electrically connected to the first end of the power module, the cathode of the first diode is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to the anode of the second diode and the anode of the third diode, one end of the second resistor is electrically connected to the cathode of the second diode, the other end of the second resistor is electrically connected to the cathode of the third diode and one end of the switch tube, and the other end of the switch tube is electrically connected to the second end of the power module. When the voltage on the bus capacitor is higher than a first preset value, the protection switch is turned off, the switch tube is turned on, and the second resistor, the switch tube and the bus capacitor form a discharge loop to reduce the voltage on the bus capacitor. When the voltage on the bus capacitor is lower than a second preset value, the protection switch is turned off, the switch tube is turned off, and the power module, the first diode, the first resistor, the second diode and the bus capacitor form a charging loop to increase the voltage on the bus capacitor.

6. The power supply device with a protection circuit as claimed in claim 5, wherein the rate of change of the voltage on the bus capacitor varies with the resistance of the discharge circuit or the charging circuit.

7. A power supply device with a protection circuit, comprising: A power module receives input power and has a first end and a second end; Power output terminal; A converter module, electrically connected between the power module and the power output terminal; A bus capacitor, electrically connected between the second end of the power module and the power output end; as well as A protection circuit, comprising a protection switch, a first diode, a first resistor, a second resistor and a switch tube, wherein the protection switch is electrically connected between the first end of the power module and the converter module, the anode of the first diode is electrically connected to the first end of the power module, the cathode of the first diode is electrically connected to one end of the first resistor, the other end of the first resistor is electrically connected to one end of the second resistor and one end of the switch tube, the other end of the second resistor is electrically connected to the power output end, and the other end of the switch tube is electrically connected to the second end of the power module. When the voltage on the bus capacitor is higher than a first preset value, the protection switch is turned off, the switch tube is turned on, and the second resistor, the switch tube and the bus capacitor form a discharge loop to reduce the voltage on the bus capacitor. When the voltage on the bus capacitor is lower than a second preset value, the protection switch is turned off, the switch tube is turned off, and the power module, the first diode, the first resistor, the second resistor and the bus capacitor form a charging loop to increase the voltage on the bus capacitor.

8. The power supply device with a protection circuit as claimed in claim 7, wherein the rate of change of the voltage on the bus capacitor varies with the resistance of the discharge circuit or the charging circuit.

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