Overcurrent detection circuit

Abstract

The utility model relates to the technical field of power electronics, and discloses an over-current detection circuit, which comprises a current sampling unit, an over-current detection unit, a threshold voltage generation unit and a signal processing unit, the output end of the current sampling unit is connected with the first input end of the overcurrent detection unit; the input end of the threshold voltage generation unit is connected with the output end of the signal processing unit, and the first output end and the second output end of the threshold voltage generation unit are correspondingly connected with the second input end and the third input end of the overcurrent detection unit respectively. The second output end of the threshold voltage generation unit is also connected with the first input end of the signal processing unit; the output end of the overcurrent detection unit is connected with the second input end of the signal processing unit. According to the utility model, the threshold voltage of the over-current detection unit can be flexibly adjusted, so that the over-current point of over-current detection can be flexibly set.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of power electronics, specifically relates to a overcurrent detection circuit. BACKGROUND

[0002] With energy storage converter application more and more widely, the safe and reliable operation of energy storage converter is more and more important, and overcurrent protection is essential when energy storage converter operates, in order to realize that energy storage system is safe and reliable operation, and wave limiting current is applied in succession, and the energy storage converter of present stage adopts fixed overcurrent point and carries out wave limiting current, and the overcurrent point is poor in adaptability, cannot be flexibly adjusted, is difficult to debug, and the ability of adapting to different working conditions is poor. CONTENT OF UTILITY MODEL

[0003] Therefore, the utility model provides a overcurrent detection circuit to solve the problem that overcurrent detection circuit cannot flexibly set overcurrent point.

[0004] The utility model provides a overcurrent detection circuit, include: current sampling unit, overcurrent detection unit, threshold voltage generating unit and signal processing unit, wherein, the input end of current sampling unit inputs the output current of equipment to be protected, and the output end of current sampling unit is connected with the first input end of overcurrent detection unit, and current sampling unit is used to convert the output current of equipment to be protected into output voltage, the input end of threshold voltage generating unit is connected with the output end of signal processing unit, and the first output end and the second output end of threshold voltage generating unit are connected with the second input end and the third input end of overcurrent detection unit respectively, and the second output end of threshold voltage generating unit is also connected with the first input end of signal processing unit, and threshold voltage generating unit is used to generate first reference voltage and second reference voltage based on the control signal outputted by signal processing unit, the output end of overcurrent detection unit is connected with the second input end of signal processing unit, and overcurrent detection unit is used to output overcurrent signal when output voltage is less than first reference voltage or output voltage is greater than second reference voltage, signal processing unit is used to adjust control signal based on the size of second reference voltage and internal preset voltage, and first reference voltage is less than second reference voltage.

[0005] The overcurrent detection circuit provided by the utility model, after threshold voltage generating unit generates first reference voltage and second reference voltage based on control signal, signal processing unit can compare second reference voltage with internal preset voltage, thereby adjusting the outputted control signal, that is, the preset voltage in signal processing unit can be adjusted to realize the flexible adjustment of first reference voltage and second reference voltage, and further realize the adjustable overcurrent point of overcurrent detection circuit, improve the accuracy and flexibility of overcurrent detection circuit, and expand the application range of overcurrent detection circuit.

[0006] In an alternative embodiment, the threshold voltage generating unit comprises: a multi-stage filtering unit, a first follower unit, a first reference voltage generating unit and a second reference voltage generating unit, wherein the input end of the multi-stage filtering unit is connected with the output end of the signal processing unit, and the output end of the multi-stage filtering unit is connected with the first end of the first follower unit; the second end and the third end of the first follower unit are both connected with the input end of the first reference voltage generating unit, and the third end of the first follower unit is also connected with the input end of the second reference voltage generating unit; the output end of the first reference voltage generating unit is connected with the second input end of the overcurrent detection unit; and the output end of the second reference voltage generating unit is connected with the third input end of the overcurrent detection unit.

[0007] The overcurrent detection circuit provided by the utility model improves the smoothness of the control signal through multiple filtering of the control signal by the multi-stage filtering unit, improves the accuracy of the first reference voltage and the second reference voltage, and thus improves the precision of the overcurrent detection circuit.

[0008] In an alternative embodiment, the multi-stage filtering unit comprises: a plurality of RC filtering circuits connected in series.

[0009] In an alternative embodiment, the first follower unit comprises: a first operational amplifier, wherein the positive input end of the first operational amplifier is connected with the output end of the multi-stage filtering unit, the negative input end of the first operational amplifier is connected with the input end of the second reference voltage generating unit, the output end of the first operational amplifier and the input end of the first reference voltage generating unit.

[0010] In an alternative embodiment, the first reference voltage generating unit comprises: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor and a second operational amplifier, wherein the first end of the first resistor is connected with the first end of the first capacitor and outputs the first reference voltage, the second end of the first resistor is connected with the first end of the second resistor and the output end of the second operational amplifier; the second end of the second resistor is connected with the first end of the third resistor and the negative input end of the second operational amplifier; the second end of the third resistor is connected with the second end of the first follower unit; the first end of the fourth resistor is grounded, the second end of the fourth resistor is connected with the first end of the fifth resistor and the positive input end of the second operational amplifier; the second end of the fifth resistor is connected with the first external power supply; and the second end of the first capacitor is grounded.

[0011] In an alternative embodiment, the overcurrent detection unit comprises a second follower unit, a first comparison unit and a second comparison unit, wherein the input end of the second follower unit is connected with the output end of the current sampling unit, the output end of the second follower unit is connected with the first input end of the first comparison unit and the first input end of the second comparison unit; the second input end of the first comparison unit inputs a first reference voltage, the output end of the first comparison unit is connected with the output end of the second comparison unit and the second input end of the signal processing unit; the second input end of the second comparison unit inputs a second reference voltage.

[0012] In an alternative embodiment, the second follower unit comprises a sixth resistor, a seventh resistor, a second capacitor, a third capacitor and a third operational amplifier, wherein the first end of the sixth resistor is connected with the output end of the current sampling unit, the second end of the sixth resistor is connected with the first end of the second capacitor and the positive input end of the third operational amplifier; the second end of the second capacitor is grounded; the reverse input end of the third operational amplifier is connected with its output end and the first end of the seventh resistor; the second end of the seventh resistor is connected with the first end of the third capacitor and the first input end of the first comparison unit; the second end of the third capacitor is grounded.

[0013] In an alternative embodiment, the first comparison unit comprises a fourth capacitor, an eighth resistor, a ninth resistor and a comparator, wherein the first end of the fourth capacitor is connected with the reverse input end of the comparator and inputs a first reference voltage, the second end of the fourth capacitor is grounded; the positive input end of the comparator is connected with the first end of the eighth resistor and the first end of the ninth resistor, the output end of the comparator is connected with the second end of the ninth resistor and the second input end of the signal processing unit; the second end of the eighth resistor is connected with the output end of the second follower unit.

[0014] In an alternative embodiment, the overcurrent detection circuit further comprises an output circuit, wherein the input end of the output circuit is connected with the output end of the overcurrent detection unit, the output end of the output circuit is connected with the second input end of the signal processing unit, the power supply end of the output circuit is connected with the second external power supply, and the output circuit is used for outputting after filtering out the interference of the overcurrent signal.

[0015] In an alternative embodiment, the overcurrent detection circuit further comprises a voltage sampling unit, wherein the input end of the voltage sampling unit is connected with the second output end of the threshold voltage generating unit, the output end of the voltage sampling unit is connected with the first input end of the signal processing unit, and the voltage sampling unit is used for collecting a second reference voltage and inputting the second reference voltage to the signal processing unit. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0017] Figure 1 is a component diagram of the overcurrent detection circuit according to the embodiment of the present application;

[0018] Figure 2 is a specific circuit structure diagram of the threshold voltage generation unit according to the embodiment of the present application;

[0019] Figure 3 is a specific circuit structure diagram of the overcurrent detection unit according to the embodiment of the present application;

[0020] Figure 4 is a specific circuit structure diagram of the output circuit according to the embodiment of the present application;

[0021] Figure 5 is a specific circuit structure diagram of the voltage sampling circuit according to the embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0023] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0024] In the description of the utility model, it is to explain, unless otherwise definite and limited, the term "installation", "link", "connection" should do the broad sense understanding, for example, can be fixed connection, also can be detachable connection, or integrally connected;Can be mechanical connection, also can be electrical connection;Can be directly connected, also can be indirectly connected through the intermediate medium, also can be the intercommunication of two elements, can be wireless connection, also can be wired connection.For the ordinary skill in the art, the specific meaning of the above-mentioned terms in the utility model can be understood according to the specific circumstances.

[0025] In addition, the technical features involved in the different embodiments of the utility model described below can be combined with each other as long as there is no conflict between them.

[0026] The embodiment provides a kind of overcurrent detection circuit, as shown in Figure 1 It includes: current sampling unit 1, overcurrent detection unit 2, threshold voltage generation unit 3 and signal processing unit 4, wherein the input end of current sampling unit 1 inputs the output current of the device to be protected, and the output end of current sampling unit 1 is connected with the first input end of overcurrent detection unit 2;The input end of threshold voltage generation unit 3 is connected with the output end of signal processing unit 4, and the first output end and the second output end of threshold voltage generation unit 3 are respectively connected with the second input end and the third input end of overcurrent detection unit 2 corresponding, and the second output end of threshold voltage generation unit 3 is also connected with the first input end of signal processing unit 4;The output end of overcurrent detection unit 2 is connected with the second input end of signal processing unit 4.

[0027] Specifically, Figure 1 In the embodiment, current sampling unit 1 is used to collect the output current of the device to be protected, and convert the output current into output voltage IV;Threshold voltage generation unit 3 is used to generate first reference voltage VL and second reference voltage VH based on the control signal output by signal processing unit 4, and first reference voltage VL is less than second reference voltage VH;Overcurrent detection unit 2 is used to output overcurrent signal Vtr when output voltage IV is less than first reference voltage VL or output voltage IV is greater than second reference voltage VH;Signal processing unit 4 is used to adjust the control signal based on the size of second reference voltage VH and internal preset voltage.

[0028] Optionally, Figure 1 In the embodiment, current sampling unit 1 can be resistance sampling circuit, hall current sensor, etc.

[0029] Exemplarily, Figure 1 In the embodiment, when overcurrent occurs in the device to be protected, overcurrent signal Vtr is low level, and signal processing unit 4 judges whether the device to be protected overflows by judging the level state of overcurrent signal Vtr.

[0030] Optionally, Figure 1 In the embodiment, the control signal can be a PWM signal, and the signal processing unit 4 can send a fixed duty ratio PWM wave according to a preset overcurrent multiple. When the signal processing unit 4 determines that the second reference voltage VH is greatly different from the internal preset voltage, the size of the second reference voltage VH can be changed by adjusting the duty ratio of the PWM signal, and then the first reference voltage VL is adjusted, so as to realize flexible adjustment of the threshold voltage. The signal processing unit 4 can also adjust the duty ratio of the PWM signal by comparing the size of the second reference voltage VH with the internal preset voltage and combining the size of the overcurrent signal Vtr. Those skilled in the art can design a specific adjustment basis for the duty ratio of the PWM signal according to actual needs, which is not limited herein.

[0031] The overcurrent detection circuit provided in the embodiment can adjust the output control signal according to the comparison between the second reference voltage and the internal preset voltage after the threshold voltage generation unit generates the first reference voltage and the second reference voltage based on the control signal. That is, the first reference voltage and the second reference voltage can be flexibly adjusted by adjusting the preset voltage in the signal processing unit, and then the overcurrent point of the overcurrent detection circuit is adjustable, the accuracy and flexibility of the overcurrent detection circuit are improved, and the application range of the overcurrent detection circuit is expanded.

[0032] In some optional embodiments, as shown in Figure 2 The threshold voltage generation unit 3 includes a multi-stage filter unit 31, a first follower unit 32, a first reference voltage generation unit 33, and a second reference voltage generation unit 32. The input end of the multi-stage filter unit 31 is connected with the output end of the signal processing unit 4, and the output end of the multi-stage filter unit 31 is connected with the first end of the first follower unit 32. The second end and the third end of the first follower unit 32 are both connected with the input end of the first reference voltage generation unit 33, and the third end of the first follower unit 32 is also connected with the input end of the second reference voltage generation unit 32. The output end of the first reference voltage generation unit 33 (i.e., one end of the output VL) is connected with the second input end of the overcurrent detection unit 2, and the output end of the second reference voltage generation unit 32 (i.e., one end of the output VH) is connected with the third input end of the overcurrent detection unit 2.

[0033] Optionally, Figure 2 In the embodiment, the multi-stage filter unit 31 includes a plurality of RC filter circuits connected in series.

[0034] Specifically, Figure 2In the embodiment, the signal processing unit 4 outputs the control signal VPWM of the PWM in turn through the multi-stage RC filter, eliminates the interference in the control signal VPWM, makes the control signal VPWM more smooth, and then the first following unit 32 performs following processing on the control signal VPWM and divides the generated signal into two paths: one path is input to the first reference voltage generating unit 33 to be converted into the first reference voltage VL, and the other path is input to the second reference voltage generating unit 34 to be converted into the second reference voltage VH.

[0035] Specifically, Figure 2 In the embodiment, the first following unit 32 includes: a first operational amplifier U4, wherein the positive input end of the first operational amplifier U4 is connected with the output end of the multi-stage filter unit 31, the negative input end of the first operational amplifier U4 is connected with the input end of the second reference voltage generating unit 32, the output end of the first operational amplifier U4 and the input end of the first reference voltage generating unit 33. When the signal processing unit adjusts the duty cycle of the control signal VPWM based on the size of the second reference voltage VH, the output voltage of the first operational amplifier U4 changes and is input to the first reference voltage generating unit 33 and the second reference voltage generating unit 34 respectively, thereby realizing dynamic adjustment of the first reference voltage VL and the second reference voltage VH.

[0036] Specifically, Figure 2 In the embodiment, the first reference voltage generating unit 33 includes: a first resistor R10, a second resistor R11, a third resistor R12, a fourth resistor R13, a fifth resistor R14, a first capacitor C6 and a second operational amplifier U5, wherein the first end of the first resistor R10 is connected with the first end of the first capacitor C6 and outputs the first reference voltage, the second end of the first resistor R10 is connected with the first end of the second resistor R11 and the output end of the second operational amplifier U5; the second end of the second resistor R11 is connected with the first end of the third resistor R12 and the negative input end of the second operational amplifier U5; the second end of the third resistor R12 is connected with the second end of the first following unit 32; the first end of the fourth resistor R13 is grounded, the second end of the fourth resistor R13 is connected with the first end of the fifth resistor R14 and the positive input end of the second operational amplifier U5; the second end of the fifth resistor R14 is connected with the first external power supply; and the second end of the first capacitor C6 is grounded.

[0037] Specifically, Figure 2In this circuit, the first external power supply voltage VCC1 is divided by the fourth resistor R13 and the fifth resistor R14 and then input to the non-inverting input of the second operational amplifier U5. The output voltage of the first operational amplifier U4 is divided by the second resistor R11 and the third resistor R12 and then input to the inverting input of the second operational amplifier U5. The output voltage of the second operational amplifier is then filtered by the first capacitor C6 and the first resistor R10 and converted into the first reference voltage VL. The second reference voltage generation unit 34 includes a resistor R15 and a capacitor C7, which is used to filter the output voltage of the first operational amplifier U4 and directly convert it into the second reference voltage VH.

[0038] In some alternative implementations, such as Figure 3 As shown, the overcurrent detection unit 2 includes: a second follower unit 21, a first comparison unit 22, and a second comparison unit 23. The input terminal (i.e., the end receiving IV) of the second follower unit 21 is connected to the output terminal of the current sampling unit 1, and the output terminal of the second follower unit 21 is connected to the first input terminal of the first comparison unit 22 and the first input terminal of the second comparison unit 23. The second input terminal of the first comparison unit 22 receives a first reference voltage, and the output terminal of the first comparison unit 22 is connected to the output terminal of the second comparison unit 23 and the second input terminal of the signal processing unit 4. The second input terminal of the second comparison unit 23 receives a second reference voltage.

[0039] Specifically, Figure 3 In the process, when there is an output voltage IV, the second follower unit 21 performs filtering, following, and impedance conversion on the output voltage IV, and then inputs the converted voltage to the first comparison unit 22 and the second comparison unit 23 respectively. When the first comparison unit 22 determines that the output voltage of the second follower unit 21 is less than the first reference voltage VL, it indicates that the output current of the device to be protected is less than the minimum limit and an overcurrent has occurred, and outputs a low-level overcurrent signal Vtr. When the second comparison unit 23 determines that the output voltage of the second follower unit 21 is greater than the second reference voltage VH, it indicates that the output current of the device to be protected is greater than the maximum limit and an overcurrent has occurred, and outputs a low-level overcurrent signal Vtr.

[0040] Specifically, Figure 3In the second following unit 21, a sixth resistor R1, a seventh resistor R2, a second capacitor C14, a third capacitor C2 and a third operational amplifier U1 are included, wherein the first end of the sixth resistor R1 is connected with the output end of the current sampling unit 1, the second end of the sixth resistor R1 is connected with the first end of the second capacitor C14 and the positive input end of the third operational amplifier U1; the second end of the second capacitor C14 is grounded; the negative input end of the third operational amplifier U1 is connected with its output end and the first end of the seventh resistor R2; the second end of the seventh resistor R2 is connected with the first end of the third capacitor C2 and the first input end of the first comparison unit 22; the second end of the third capacitor C2 is grounded. The output voltage IV is input to the third operational amplifier U1 after being filtered by the sixth resistor R1 and the second capacitor C14 for following processing, and after the impedance conversion is realized synchronously, the output voltage IV is input to the first comparison unit 22 and the second comparison unit 23 after being filtered by the seventh resistor R2 and the third capacitor C2.

[0041] Specifically, Figure 3 In the first comparison unit 22, a fourth capacitor C3, an eighth resistor R5, a ninth resistor R6 and a comparator U3 are included, wherein the first end of the fourth capacitor C3 is connected with the negative input end of the comparator U3 and inputs a first reference voltage, the second end of the fourth capacitor C3 is grounded; the positive input end of the comparator U3 is connected with the first end of the eighth resistor R5 and the first end of the ninth resistor R6, the output end of the comparator U3 is connected with the second end of the ninth resistor R6 and the second input end of the signal processing unit 4; the second end of the eighth resistor R5 is connected with the output end of the second following unit 21. The second comparison unit 23 includes a capacitor C4, resistors R3 and R4 and a comparator U2.

[0042] Specifically, Figure 3 In the first comparison unit 22, when the output voltage IV after processing is determined to be less than the first reference voltage VL, the comparator U3 outputs an undercurrent signal Vtr of low level; when the second comparison unit 23 determines that the output voltage IV after processing is greater than the second reference voltage VH, the comparator U2 outputs an undercurrent signal Vtr of low level. The resistors R3 and R4 are a setting loop of the second reference voltage VH, and the eighth resistor R5 and the ninth resistor R6 are a setting loop of the first reference voltage VL.

[0043] In some optional embodiments, as shown in Figure 4 The undercurrent detection circuit further includes an output circuit 5, wherein the input end of the output circuit 5 is connected with the output end of the undercurrent detection unit 2, the output end of the output circuit 5 is connected with the second input end of the signal processing unit 4, the power supply end of the output circuit 5 is connected with the second external power supply, and the output circuit 5 is used for outputting after filtering out the interference of the undercurrent signal.

[0044] Specifically, Figure 4In the embodiment, resistors R7 and R8 pull up the output signals of comparators U2 and U3 based on the second external power supply voltage VCC2, and then the output signals are filtered by resistor R9 and capacitor C5.

[0045] In some alternative embodiments, as shown in FIG. Figure 5 As shown in FIG. The overcurrent detection circuit further comprises a voltage sampling unit 6, wherein an input end of the voltage sampling unit 6 is connected with a second output end of the threshold voltage generating unit 3, an output end of the voltage sampling unit 6 is connected with a first input end of the signal processing unit 4, and the voltage sampling unit 6 is configured to collect the second reference voltage and input the second reference voltage to the signal processing unit 4.

[0046] Specifically, Figure 5 In the embodiment, the second reference voltage VH is followed by an operational amplifier U6, and then is converted into a sampling voltage VHADC after impedance conversion and filtering by a filter circuit composed of resistor R19 and capacitor C11, and is input to the signal processing unit 4.

[0047] It should be noted that the embodiment only describes the working process of one of the isolation driving circuits, and the internal structure and working process of the other isolation driving circuits are consistent with the content of the embodiment, and thus will not be described herein.

[0048] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. An overcurrent detection circuit, characterized by comprising: The application relates to a current sampling unit, an overcurrent detection unit, a threshold voltage generation unit and a signal processing unit, wherein, an input end of the current sampling unit inputs an output current of a device to be protected, an output end of the current sampling unit is connected with a first input end of the overcurrent detection unit, and the current sampling unit is used for converting the output current of the device to be protected into an output voltage; an input end of the threshold voltage generation unit is connected with an output end of the signal processing unit, a first output end and a second output end of the threshold voltage generation unit are correspondingly connected with a second input end and a third input end of the overcurrent detection unit, the second output end of the threshold voltage generation unit is also connected with a first input end of the signal processing unit, and the threshold voltage generation unit is used for generating a first reference voltage and a second reference voltage based on a control signal output by the signal processing unit; an output end of the overcurrent detection unit is connected with a second input end of the signal processing unit, and the overcurrent detection unit is used for outputting an overcurrent signal when the output voltage is less than the first reference voltage or the output voltage is greater than the second reference voltage; the signal processing unit is used for adjusting the control signal based on the size of the second reference voltage and an internal preset voltage; the first reference voltage is less than the second reference voltage. The threshold voltage generation unit comprises a multi-stage filter unit, a first follower unit, a first reference voltage generation unit and a second reference voltage generation unit, wherein, 2. The overcurrent detection circuit of claim 1, wherein an input end of the multi-stage filter unit is connected with an output end of the signal processing unit, and an output end of the multi-stage filter unit is connected with a first end of the first follower unit; a second end and a third end of the first follower unit are both connected with an input end of the first reference voltage generation unit, and the third end of the first follower unit is also connected with an input end of the second reference voltage generation unit; an output end of the first reference voltage generation unit is connected with a second input end of the overcurrent detection unit; an output end of the second reference voltage generation unit is connected with a third input end of the overcurrent detection unit. The multi-stage filter unit comprises:

3. The overcurrent detection circuit of claim 2, wherein a plurality of RC filter circuits connected in series. The first follower unit comprises a first operational amplifier, wherein, 4. The overcurrent detection circuit of claim 2, wherein a positive input end of the first operational amplifier is connected with an output end of the multi-stage filter unit, a negative input end of the first operational amplifier is connected with an input end of the second reference voltage generation unit, an output end of the first operational amplifier and an input end of the first reference voltage generation unit. The first reference voltage generation unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor and a second operational amplifier, wherein, 5. The overcurrent detection circuit of claim 2, wherein, a first end of the first resistor is connected with a first end of the first capacitor and outputs the first reference voltage, a second end of the first resistor is connected with a first end of the second resistor and an output end of the second operational amplifier; a second end of the second resistor is connected with a first end of the third resistor and a negative input end of the second operational amplifier; ​ The second end of the third resistor is connected with the second end of the first follower unit; The first end of the fourth resistor is grounded, and the second end of the fourth resistor is connected with the first end of the fifth resistor and the positive input end of the second operational amplifier; The second end of the fifth resistor is connected with the first external power supply; The second end of the first capacitor is grounded.

6. The overcurrent detection circuit of claim 1, wherein The overcurrent detection unit comprises a second follower unit, a first comparison unit and a second comparison unit, wherein, The input end of the second follower unit is connected with the output end of the current sampling unit, and the output end of the second follower unit is connected with the first input end of the first comparison unit and the first input end of the second comparison unit; The second input end of the first comparison unit inputs the first reference voltage, and the output end of the first comparison unit is connected with the output end of the second comparison unit and the second input end of the signal processing unit; The second input end of the second comparison unit inputs the second reference voltage.

7. The overcurrent detection circuit of claim 6, wherein The second follower unit comprises a sixth resistor, a seventh resistor, a second capacitor, a third capacitor and a third operational amplifier, wherein, The first end of the sixth resistor is connected with the output end of the current sampling unit, and the second end of the sixth resistor is connected with the first end of the second capacitor and the positive input end of the third operational amplifier; The second end of the second capacitor is grounded; The reverse input end of the third operational amplifier is connected with the output end thereof and the first end of the seventh resistor; The second end of the seventh resistor is connected with the first end of the third capacitor and the first input end of the first comparison unit; The second end of the third capacitor is grounded.

8. The overcurrent detection circuit of claim 7, wherein, The first comparison unit comprises a fourth capacitor, an eighth resistor, a ninth resistor and a comparator, wherein, The first end of the fourth capacitor is connected with the reverse input end of the comparator and inputs the first reference voltage, and the second end of the fourth capacitor is grounded; The positive input end of the comparator is connected with the first end of the eighth resistor and the first end of the ninth resistor, and the output end of the comparator is connected with the second end of the ninth resistor and the second input end of the signal processing unit; The second end of the eighth resistor is connected with the output end of the second follower unit.

9. The overcurrent detection circuit of claim 1, wherein, Further comprising: an output circuit, wherein, the input end of the output circuit is connected with the output end of the overcurrent detection unit, the output end of the output circuit is connected with the second input end of the signal processing unit, the power supply end of the output circuit is connected with the second external power supply, and the output circuit is used for outputting after filtering out the interference of the overcurrent signal.

10. The overcurrent detection circuit of claim 1, wherein, Further comprising: a voltage sampling unit, wherein, the input end of the voltage sampling unit is connected with the second output end of the threshold voltage generation unit, the output end of the voltage sampling unit is connected with the first input end of the signal processing unit, and the voltage sampling unit is used for collecting the second reference voltage and inputting the second reference voltage to the signal processing unit.

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