Bus overcurrent protection circuit and frequency converter
A cost-effective bus overcurrent protection circuit using basic circuit elements addresses the high-cost issues of traditional methods, ensuring inverter protection and operation by detecting and responding to bus current signals.
Patent Information
- Application Number
- CN202323454811.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-18
- Publication Date
- 2024-12-10
- Estimated Expiration
- 2033-12-18
AI Technical Summary
Existing bus overcurrent protection methods for inverters, such as using fuses or drive optocouplers, are costly and do not effectively protect the inverter from bus overcurrent, which can lead to damage and operational issues.
A bus overcurrent protection circuit composed of basic circuit elements, including a power module, overcurrent detection module, and overcurrent protection module, which detects and responds to bus current signals to trigger overcurrent protection, reducing costs by using components like resistors, capacitors, and transistors.
The proposed circuit effectively protects against bus overcurrent while significantly lowering costs compared to traditional methods, ensuring the inverter's normal operation without the need for expensive components like fuses or drive optocouplers.
Smart Images
Figure CN222147153U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of power electronics, in particular to a busbar overcurrent protection circuit and a frequency converter. Background Art
[0002] Bus overcurrent protection is an important overcurrent protection function of the inverter. If the bus overcurrent protection is not timely, it will easily damage the inverter and affect the normal operation of the inverter. At present, the inverter is usually protected from bus overcurrent by connecting a fuse in series with the inverter, or by a drive optocoupler with a Vce detection function. However, the cost of these bus overcurrent protection methods is usually high. Utility Model Content
[0003] The main purpose of the utility model is to provide a busbar overcurrent protection circuit, aiming to reduce the cost of busbar overcurrent protection for a frequency converter.
[0004] To achieve the above object, the utility model proposes a bus overcurrent protection circuit, the bus overcurrent protection circuit is connected between the power supply P terminal and the power supply N terminal of the target device, and the bus overcurrent protection circuit includes a power supply module, an overcurrent detection module and an overcurrent protection module;
[0005] The overcurrent detection module is respectively connected to the power supply module and the overcurrent protection module;
[0006] The overcurrent detection module is used to receive the bus current signal output by the target device, and output an overcurrent trigger signal to the overcurrent protection module when the bus current signal drives each switch tube inside the overcurrent detection module to be in a conducting state;
[0007] The overcurrent protection module is used to receive the overcurrent trigger signal to trigger the overcurrent protection module to output an overcurrent protection signal, and the overcurrent protection signal is used to perform bus overcurrent protection on the target device.
[0008] Optionally, the overcurrent detection module includes an overcurrent detection unit and an overcurrent triggering unit;
[0009] The overcurrent detection unit is respectively connected to the target device, the power module and the overcurrent trigger unit, and the overcurrent trigger unit is respectively connected to the power module and the overcurrent protection module;
[0010] The overcurrent detection unit is used to receive the bus current signal output by the target device, and output a switch tube conduction signal to the overcurrent trigger unit when the bus current signal drives each switch tube inside the overcurrent detection unit to be in a conduction state;
[0011] The overcurrent trigger unit is used to control the internal switch tube to be turned on according to the received switch tube conduction signal, so as to output the overcurrent trigger signal to the overcurrent protection module.
[0012] Optionally, the overcurrent detection unit includes a first switch tube, a second switch tube, a first resistor, a second resistor, a third resistor, a first capacitor and a second capacitor;
[0013] The emitter of the first switch tube is connected to one end of the first resistor, the base of the first switch tube is connected to the base of the second switch tube and one end of the first capacitor, the collector of the first switch tube is connected to one end of the second resistor, the other end of the first resistor is connected to the power supply P end of the target device, and the other end of the second resistor and the other end of the first capacitor are connected to the output end of the power module;
[0014] The emitter of the second switching tube is connected to one end of the third resistor, the collector of the second switching tube is connected to one end of the second capacitor and the input end of the overcurrent trigger unit, the other end of the third resistor is connected to the power supply P end of the target device, and the other end of the second capacitor is connected to the output end of the power module.
[0015] Optionally, both the first switch tube and the second switch tube are PNP transistors.
[0016] Optionally, the overcurrent trigger unit includes a third switch tube, a first voltage regulator diode and a fourth resistor;
[0017] One end of the fourth resistor is connected to the collector of the second switch tube and the base of the third switch tube, the collector of the third switch tube is connected to the cathode of the first voltage regulator diode, the emitter of the third switch tube is connected to the input end of the overcurrent protection module, and the other end of the fourth resistor and the anode of the first voltage regulator diode are connected to the output end of the power module.
[0018] Optionally, the third switch tube is an NPN transistor.
[0019] Optionally, the resistance of the fourth resistor is smaller than the resistance of the third resistor.
[0020] Optionally, the overcurrent protection module includes an optical coupler, a fifth resistor, a sixth resistor, a seventh resistor and a third capacitor;
[0021] The anode input terminal of the optocoupler is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the power supply P terminal of the target device, the cathode input terminal of the optocoupler is connected to the output terminal of the overcurrent detection module, the emitter output terminal of the optocoupler is the output terminal of the overcurrent protection signal, the emitter output terminal of the optocoupler is connected to one end of the sixth resistor and one end of the seventh resistor, the collector output terminal of the optocoupler is connected to the other end of the seventh resistor and the power supply N terminal of the target device, the other end of the sixth resistor is connected to the power supply, one end of the sixth resistor and one end of the seventh resistor are connected to one end of the third capacitor, and the other end of the third capacitor is connected to the power supply N terminal of the target device.
[0022] Optionally, the power module includes a second voltage stabilizing diode, a fourth capacitor and an eighth resistor;
[0023] One end of the eighth resistor is connected to the power supply N terminal of the target device, the other end of the eighth resistor is connected to the input end of the overcurrent detection module, the anode of the second voltage regulator diode and one end of the fourth capacitor, and the cathode of the second voltage regulator diode is connected to the other end of the fourth capacitor and the power supply P terminal of the target device.
[0024] In addition, the utility model also provides a frequency converter, including the above-mentioned bus overcurrent protection circuit, which is specifically referred to above and will not be described again here.
[0025] The utility model provides a bus overcurrent protection circuit, which is connected between the power supply P terminal and the power supply N terminal of the target device. The bus overcurrent protection circuit includes a power module, an overcurrent detection module and an overcurrent protection module. The overcurrent detection module is respectively connected to the power module and the overcurrent protection module, so that the normal operation of the overcurrent detection module can be driven by the power module. The overcurrent detection module will receive the bus current signal output by the target device during operation. If the bus current signal can drive all the switch tubes inside the overcurrent detection module to be in a conducting state, it is necessary to output an overcurrent trigger signal to the overcurrent protection module to trigger the overcurrent protection module to output an overcurrent protection signal for performing bus overcurrent protection on the target device. Since the power module, the overcurrent detection module and the overcurrent protection module can all be composed of basic circuit elements, and the basic circuit elements are lower in cost than components such as fuses and drive optocouplers with Vce detection functions, the utility model reduces the cost of bus overcurrent protection for the inverter by constructing a bus overcurrent protection circuit composed of basic circuit elements and capable of performing overcurrent protection on the bus. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.
[0027] Figure 1 It is a module schematic diagram of an embodiment of a busbar overcurrent protection circuit of the utility model;
[0028] Figure 2 It is a schematic diagram of a module of an embodiment of an overcurrent detection module in a busbar overcurrent protection circuit of the utility model, including an overcurrent detection unit and an overcurrent trigger unit;
[0029] Figure 3 It is a structural schematic diagram of an embodiment of a busbar overcurrent protection circuit of the utility model.
[0030] The purpose, features and advantages of the present invention will be further described in conjunction with the embodiments and with reference to the accompanying drawings.
[0031] Description of Figure Numbers:
[0032] Label name Label name 10 Power Module R1-R8 resistance 20 Overcurrent detection module C1-C4 capacitance 30 Overcurrent protection module ZD1-ZD2 Zener diode 21 Overcurrent detection unit Q1-Q3 Switching tube 22 Overcurrent trigger unit PC1 Optocoupler FO Overcurrent protection signal DETAILED DESCRIPTION
[0033] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0034] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0035] It should be noted that the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.
[0036] Bus overcurrent protection is an important overcurrent protection function of the inverter. If the bus overcurrent protection is not timely, it will easily damage the inverter and affect the normal operation of the inverter. At present, the inverter is usually protected from bus overcurrent by connecting a fuse in series with the inverter, or by a drive optocoupler with a Vce detection function. However, the cost of these bus overcurrent protection methods is usually high.
[0037] Based on this, the utility model provides a busbar overcurrent protection circuit, referring to Figure 1 In one embodiment, the bus overcurrent protection circuit includes a power module 10, an overcurrent detection module 20 and an overcurrent protection module 30; the first input end of the power module 10 is connected to the power P end of the target device, the second input end of the power module 10 is connected to the power N end of the target device, the output end of the power module 10 is connected to the first input end of the overcurrent detection module 20, the second input end of the overcurrent detection module 20 is connected to the power P end of the target device, the output end of the overcurrent detection module 20 is connected to the first input end of the overcurrent protection module 30, the second input end of the overcurrent protection module 30 is connected to the power P end of the target device, and the third input end of the overcurrent protection module 30 is connected to the power N end of the target device;
[0038] The overcurrent detection module 20 is used to receive the bus current signal output by the target device, and when the bus current signal drives each switch tube inside the overcurrent detection module 20 to be in the on state, outputs an overcurrent trigger signal to the overcurrent protection module 30; the overcurrent protection module 30 is used to receive the overcurrent trigger signal to trigger the overcurrent protection module 30 to output an overcurrent protection signal, and the overcurrent protection signal is used to perform bus overcurrent protection on the target device.
[0039] It should be noted that the target device refers to a device carrying a bus, and the target device may be a frequency converter, a servo drive, etc. The bus current signal is used to characterize the bus current condition of the target device at the current moment, and the overcurrent trigger signal is used to trigger the overcurrent protection module 30 to output an overcurrent protection signal for performing bus overcurrent protection on the target device. The power module 10, the overcurrent detection module 20, and the overcurrent protection module 30 are all composed of basic circuit elements, and the basic circuit elements are used to characterize commonly used circuit elements, and the basic circuit elements may include resistors, capacitors, inductors, crystal diodes, voltage regulator diodes, transistors, optocouplers, etc. It can be understood that since the basic circuit elements are commonly used circuit elements, the basic circuit elements are usually cheaper than non-basic circuit elements, that is, the cost is lower, and therefore the cost of the bus overcurrent protection circuit composed of the basic circuit elements is also lower than that of the bus overcurrent protection circuit composed of non-basic circuit elements.
[0040] In addition, it should be noted that the power supply P terminal and the power supply N terminal of the target device can actually be used to represent the PN terminal of the bus in the target device.
[0041] The present embodiment provides a bus overcurrent protection circuit, which is connected between the power supply P terminal and the power supply N terminal of the target device, and includes a power module 10, an overcurrent detection module 20 and an overcurrent protection module 30, wherein the overcurrent detection module 20 is respectively connected to the power module 10 and the overcurrent protection module 30, so that the normal operation of the overcurrent detection module 20 can be driven by the power module 10. During operation, the overcurrent detection module 20 receives the bus current signal output by the target device, and if the bus current signal can drive all the switch tubes inside the overcurrent detection module 20 to be in the on state, it is necessary to output an overcurrent trigger signal to the overcurrent protection module 30 to trigger the overcurrent protection module 30 to output an overcurrent protection signal for bus overcurrent protection of the target device. Since the power module 10, the overcurrent detection module 20 and the overcurrent protection module 30 can all be composed of basic circuit elements, and the basic circuit elements are lower in cost than components such as fuses and drive optocouplers with Vce detection functions, this embodiment reduces the cost of bus overcurrent protection for the inverter by constructing a bus overcurrent protection circuit composed of basic circuit elements and capable of performing overcurrent protection on the bus.
[0042] In one possible implementation, see Figure 2 The overcurrent detection module 20 includes an overcurrent detection unit 21 and an overcurrent trigger unit 22; a first input end of the overcurrent detection unit 21 is connected to the output end of the power module 10, a second input end of the overcurrent detection unit 21 is connected to the power supply P end of the target device, an output end of the overcurrent detection unit 21 is connected to the input end of the overcurrent trigger unit 22, and an output end of the overcurrent trigger unit 22 is connected to the input end of the overcurrent protection module 30;
[0043] The overcurrent detection unit 21 is used to receive the bus current signal output by the target device, and when the bus current signal drives each switch tube inside the overcurrent detection unit 21 to be in the on state, output a switch tube conduction signal to the overcurrent trigger unit 22; the overcurrent trigger unit 22 is used to control the internal switch tube to be turned on according to the received switch tube conduction signal, so as to output an overcurrent trigger signal to the overcurrent protection module 30.
[0044] In this embodiment, if the bus current signal received by the overcurrent detection unit 21 can drive all the switch tubes inside the overcurrent detection unit 21 to be in the on state, it can be determined that the target device has a bus overcurrent problem. In order to ensure that there is sufficient power to trigger the overcurrent protection module 30 to output an overcurrent protection signal, it is necessary to first use the overcurrent detection unit 21 to output a switch tube conduction signal to the overcurrent trigger unit 22, so as to prompt the switch tube inside the overcurrent trigger unit 22 to turn on, and then prompt the overcurrent trigger unit 22 to output an overcurrent trigger signal that can trigger the overcurrent protection module 30 to output an overcurrent protection signal, thereby ensuring the normal operation of the bus overcurrent protection circuit.
[0045] As an example, see Figure 3 The overcurrent detection unit 21 may include a first switch tube Q1, a second switch tube Q2, a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1 and a second capacitor C2, and the overcurrent trigger unit 22 may include a third switch tube Q3, a first voltage regulator diode ZD1 and a fourth resistor R4;
[0046] The emitter of the first switch tube Q1 is connected to one end of the first resistor R1, the base of the first switch tube Q1 is connected to the base of the second switch tube Q2 and one end of the first capacitor C1, the collector of the first switch tube Q1 is connected to one end of the second resistor R2, the other end of the first resistor R1 is connected to the power supply P end of the target device, and the other end of the second resistor R2 and the other end of the first capacitor C1 are connected to the output end of the power module 10;
[0047] The emitter of the second switch tube Q2 is connected to one end of the third resistor R3, the collector of the second switch tube Q2 is connected to one end of the second capacitor C2 and one end of the fourth resistor R4, the other end of the third resistor R3 is connected to the power supply P end of the target device, and the other end of the second capacitor C2 is connected to the output end of the power module 10;
[0048] One end of the fourth resistor R4 is connected to the base of the third switch tube Q3, the collector of the third switch tube Q3 is connected to the cathode of the first voltage regulator diode ZD1, the emitter of the third switch tube Q3 is connected to the input end of the overcurrent protection module 30, and the other end of the fourth resistor R4 and the anode of the first voltage regulator diode ZD1 are connected to the output end of the power module 10.
[0049] It should be noted that the first switch tube Q1 and the second switch tube Q2 can both be PNP type transistors, or both can be NPN type transistors (if the first switch tube Q1 and the second switch tube Q2 are both NPN type transistors, the circuit structure of the overcurrent detection module 20 also needs to be adaptively changed), and this embodiment does not specifically limit this. The third switch tube Q3 can be an NPN type transistor or a PNP type transistor, and this embodiment does not specifically limit this. In this embodiment, the first switch tube Q1 and the second switch tube Q2 are both PNP type transistors, and the third switch tube Q3 is an NPN type transistor.
[0050] In addition, it should be noted that in order to ensure that the second switch tube Q2 can successfully drive the third switch tube Q3 to be turned on after being turned on, the resistance value of the fourth resistor R4 should be smaller than the resistance value of the third resistor R3.
[0051] In this example, when the bus current signal of the target device is normal, since the emitter voltage of the first switch tube Q1 is greater than the emitter voltage of the second switch tube Q2, the second switch tube Q2 will not be turned on, and the third switch tube Q3 will not be turned on either, that is, among the first switch tube Q1, the second switch tube Q2 and the third switch tube Q3, only the first switch tube Q1 is in the on state, and thus the overcurrent trigger signal will not be output to the overcurrent protection module 30. When the bus current signal of the target device is abnormal, that is, when the bus current signal of the target device is too large, the emitter voltage of the first switch tube Q1 will be pulled down. If the emitter voltage of the first switch tube Q1 is pulled down to be less than the emitter voltage of the second switch tube Q2, the second switch tube Q2 will be turned on at this time; and after the second switch tube Q2 is in the on state, the base voltage of the third switch tube Q3 will be pulled up to cause the third switch tube Q3 to be turned on, thereby outputting the overcurrent trigger signal to the overcurrent protection module 30.
[0052] In one possible implementation, see Figure 3 , the overcurrent protection module 30 may include an optical coupler PC1, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7 and a third capacitor C3;
[0053] The anode input terminal of the optocoupler PC1 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to the power supply P terminal of the target device, the cathode input terminal of the optocoupler PC1 is connected to the output terminal of the overcurrent detection module 20, the emitter output terminal of the optocoupler PC1 is the output terminal of the overcurrent protection signal FO, the emitter output terminal of the optocoupler PC1 is connected to one end of the sixth resistor R6 and one end of the seventh resistor R7, the collector output terminal of the optocoupler PC1 is connected to the other end of the seventh resistor R7 and the power supply N terminal of the target device, the other end of the sixth resistor R6 is connected to a 5V power supply, one end of the sixth resistor R6 and one end of the seventh resistor R7 are connected to one end of the third capacitor C3, and the other end of the third capacitor C3 is connected to the power supply N terminal of the target device.
[0054] In this embodiment, after the optocoupler PC1 receives the overcurrent trigger signal output by the overcurrent detection module 20, the primary side of the optocoupler PC1 will be turned on, thereby being able to control the signal output by the secondary side of the optocoupler PC1 from a high level signal to a low level signal, and the low level signal is the overcurrent protection signal FO.
[0055] In other embodiments, after the primary side of the optocoupler PC1 is turned on, the signal output by the secondary side of the optocoupler PC1 may be controlled to change from a low level signal to a high level signal, and the high level signal is the overcurrent protection signal FO.
[0056] In one possible implementation, see Figure 3 , the power module 10 may include a second voltage stabilizing diode ZD2, a fourth capacitor C4 and an eighth resistor R8;
[0057] One end of the eighth resistor R8 is connected to the power supply N terminal of the target device, the other end of the eighth resistor R8 is connected to the input end of the overcurrent detection module 20, the anode of the second voltage zener diode ZD2 and one end of the fourth capacitor C4, and the cathode of the second voltage zener diode ZD2 is connected to the other end of the fourth capacitor C4 and the power supply P terminal of the target device.
[0058] In this embodiment, one end of the eighth resistor R8 is connected to the power supply N terminal of the target device, and the cathode of the second voltage stabilizing diode ZD2 is connected to the power supply P terminal of the target device, that is, the loop composed of the two voltage stabilizing diodes ZD2, the fourth capacitor C4 and the eighth resistor R8 is mounted on the target device, so that under the action of the voltage signal output by the target device, the loop composed of the two voltage stabilizing diodes ZD2, the fourth capacitor C4 and the eighth resistor R8 will form a stable voltage, so that this loop can be regarded as a power supply. Therefore, by using the output voltage signal of the target device, this embodiment can directly carry a power supply module that can be used to drive the normal operation of the overcurrent detection module 20 inside the target device, so that there is no need to set up another power supply module outside the target device for driving the normal operation of the overcurrent detection module 20, thereby avoiding the circuit isolation operation caused by setting up an external power supply module, which can also reduce the cost of the bus overcurrent protection circuit to a certain extent.
[0059] The utility model also provides a frequency converter, which includes a bus overcurrent protection circuit. The structure of the bus overcurrent protection circuit can refer to the above embodiment and will not be described in detail here. As it should be, since the frequency converter of this embodiment includes all technical solutions of all embodiments of the above bus overcurrent protection circuit, and the technical effects achieved are also exactly the same, they will not be described in detail here.
[0060] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. A busbar overcurrent protection circuit, characterized in that: The bus overcurrent protection circuit is connected between the power supply P terminal and the power supply N terminal of the target device, and the bus overcurrent protection circuit includes a power supply module, an overcurrent detection module and an overcurrent protection module; The overcurrent detection module is respectively connected to the power supply module and the overcurrent protection module; The overcurrent detection module is used to receive the bus current signal output by the target device, and output an overcurrent trigger signal to the overcurrent protection module when the bus current signal drives each switch tube inside the overcurrent detection module to be in a conducting state; The overcurrent protection module is used to receive the overcurrent trigger signal to trigger the overcurrent protection module to output an overcurrent protection signal, and the overcurrent protection signal is used to perform bus overcurrent protection on the target device.
2. The busbar overcurrent protection circuit according to claim 1, characterized in that: The overcurrent detection module includes an overcurrent detection unit and an overcurrent triggering unit; The overcurrent detection unit is respectively connected to the target device, the power module and the overcurrent trigger unit, and the overcurrent trigger unit is respectively connected to the power module and the overcurrent protection module; The overcurrent detection unit is used to receive the bus current signal output by the target device, and output a switch tube conduction signal to the overcurrent trigger unit when the bus current signal drives each switch tube inside the overcurrent detection unit to be in a conduction state; The overcurrent trigger unit is used to control the internal switch tube to be turned on according to the received switch tube conduction signal, so as to output the overcurrent trigger signal to the overcurrent protection module.
3. The busbar overcurrent protection circuit according to claim 2, characterized in that: The overcurrent detection unit includes a first switch tube, a second switch tube, a first resistor, a second resistor, a third resistor, a first capacitor and a second capacitor; The emitter of the first switch tube is connected to one end of the first resistor, the base of the first switch tube is connected to the base of the second switch tube and one end of the first capacitor, the collector of the first switch tube is connected to one end of the second resistor, the other end of the first resistor is connected to the power supply P end of the target device, and the other end of the second resistor and the other end of the first capacitor are connected to the output end of the power module; The emitter of the second switching tube is connected to one end of the third resistor, the collector of the second switching tube is connected to one end of the second capacitor and the input end of the overcurrent trigger unit, the other end of the third resistor is connected to the power supply P end of the target device, and the other end of the second capacitor is connected to the output end of the power module.
4. The busbar overcurrent protection circuit according to claim 3, characterized in that: The first switch tube and the second switch tube are both PNP type triodes.
5. The busbar overcurrent protection circuit according to claim 3, characterized in that: The overcurrent trigger unit includes a third switch tube, a first voltage stabilizing diode and a fourth resistor; One end of the fourth resistor is connected to the collector of the second switch tube and the base of the third switch tube, the collector of the third switch tube is connected to the cathode of the first voltage regulator diode, the emitter of the third switch tube is connected to the input end of the overcurrent protection module, and the other end of the fourth resistor and the anode of the first voltage regulator diode are connected to the output end of the power module.
6. The busbar overcurrent protection circuit according to claim 5, characterized in that: The third switch tube is an NPN transistor.
7. The busbar overcurrent protection circuit according to claim 5, characterized in that: The resistance of the fourth resistor is smaller than the resistance of the third resistor.
8. The busbar overcurrent protection circuit according to claim 1, characterized in that: The overcurrent protection module includes an optical coupler, a fifth resistor, a sixth resistor, a seventh resistor and a third capacitor; The anode input terminal of the optocoupler is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the power supply P terminal of the target device, the cathode input terminal of the optocoupler is connected to the output terminal of the overcurrent detection module, the emitter output terminal of the optocoupler is the output terminal of the overcurrent protection signal, the emitter output terminal of the optocoupler is connected to one end of the sixth resistor and one end of the seventh resistor, the collector output terminal of the optocoupler is connected to the other end of the seventh resistor and the power supply N terminal of the target device, the other end of the sixth resistor is connected to the power supply, one end of the sixth resistor and one end of the seventh resistor are connected to one end of the third capacitor, and the other end of the third capacitor is connected to the power supply N terminal of the target device.
9. The busbar overcurrent protection circuit according to claim 1, characterized in that: The power module includes a second voltage stabilizing diode, a fourth capacitor and an eighth resistor; One end of the eighth resistor is connected to the power supply N terminal of the target device, the other end of the eighth resistor is connected to the input end of the overcurrent detection module, the anode of the second voltage regulator diode and one end of the fourth capacitor, and the cathode of the second voltage regulator diode is connected to the other end of the fourth capacitor and the power supply P terminal of the target device.
10. A frequency converter, characterized in that: The frequency converter comprises a bus overcurrent protection circuit as claimed in any one of claims 1 to 9.