Current detection circuit and circuit breaker

Abstract

The utility model provides a kind of current detection circuit and circuit breaker, current detection circuit includes leakage current transformer, rectifier unit, current sampling unit, phase sampling unit and control unit;Leakage current transformer is electrically connected with the input end of rectifier unit and the input end of phase sampling unit respectively;The output end of rectifier unit is electrically connected with the amplitude sampling input end of control unit by current sampling unit;The output end of phase sampling unit is electrically connected with the phase sampling input end of control unit;Control unit is used to obtain the ground fault current of the loop to be measured according to the amplitude sampling signal output by current sampling unit and the phase sampling signal output by phase sampling unit.This utility model utilizes original leakage current transformer, respectively configures corresponding current sampling unit and phase sampling unit, so that it is not necessary to additionally set ground fault current transformer for ground fault current detection, and the volume and cost of circuit breaker are reduced.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, specifically to a current detection circuit and a circuit breaker. Background Technology

[0002] With the improvement of electrical safety standards and the advancement of technology, circuit breakers have become more comprehensive in their functions. These circuit breakers can not only prevent fires caused by short circuits or overloads, but also quickly cut off the power supply to protect safety in the event of leakage or grounding faults.

[0003] Existing circuit breakers typically add a dedicated ground fault current transformer for ground fault current detection to the existing leakage current transformer to achieve ground fault protection. However, this method results in a larger circuit breaker size and higher cost. Utility Model Content

[0004] In view of the shortcomings of the existing technology, this utility model provides a current detection circuit and a circuit breaker.

[0005] In one embodiment, the present invention provides a current detection circuit, which includes a leakage current transformer, a rectifier unit, a current sampling unit, a phase sampling unit, and a control unit. The leakage current transformer is electrically connected to the input terminal of the rectifier unit and the input terminal of the phase sampling unit, respectively, and is used to detect the current of the circuit under test and output the corresponding detection current. The output of the rectifier unit is electrically connected to the amplitude sampling input of the control unit through the current sampling unit. The current sampling unit is used to sample the current amplitude of the detection current after rectification by the rectifier unit and output the amplitude sampling signal to the control unit. The output of the phase sampling unit is electrically connected to the phase sampling input of the control unit, and is used to sample the current phase of the detected current and output a phase sampling signal to the control unit. The control unit is used to obtain the ground fault current of the circuit under test based on the amplitude sampling signal and the phase sampling signal.

[0006] In one embodiment, the current sampling unit includes a current sampling resistor and an amplification subunit; The negative output terminal of the rectifier unit is electrically connected to the input terminal of the amplifier subunit and is used to ground through the current sampling resistor. The output terminal of the amplifier subunit is electrically connected to the amplitude sampling input terminal of the control unit.

[0007] In one embodiment, the amplification subunit includes an amplitude sampling operational amplifier; The inverting input of the amplitude sampling operational amplifier is electrically connected to the negative output of the rectifier unit, the non-inverting input of the amplitude sampling operational amplifier is used for grounding, and the output of the amplitude sampling operational amplifier is electrically connected to the amplitude sampling input of the control unit.

[0008] In one embodiment, the phase sampling unit includes a phase sampling operational amplifier; The non-inverting input of the phase sampling operational amplifier is electrically connected to the positive output of the leakage current transformer, the inverting input of the phase sampling operational amplifier is used for grounding, and the output of the phase sampling operational amplifier is electrically connected to the phase sampling input of the control unit.

[0009] In one embodiment, the current detection circuit further includes a power supply unit; The input terminal of the power supply unit is electrically connected to the output terminal of the rectifier unit, and the output terminal of the power supply unit is electrically connected to the power supply terminal of the control unit.

[0010] In one embodiment, the power supply unit includes a Zener diode, a pull-down resistor, a monitoring chip, and a switching transistor; The cathode of the Zener diode is electrically connected to the positive output terminal of the rectifier unit, the input terminal of the switching transistor, and the power supply terminal of the control unit, respectively. The anode of the Zener diode is electrically connected to the input terminal of the monitoring chip and is used to ground through a pull-down resistor. The output terminal of the monitoring chip is electrically connected to the control electrode of the switching transistor, and the output terminal of the switching transistor is used to ground. The monitoring chip is used to control the switching transistor to turn on when the Zener diode is broken down.

[0011] In one embodiment, the power supply unit further includes a TVS diode; The cathode of the TVS diode is electrically connected to the positive output terminal of the rectifier unit, the input terminal of the switching transistor, the cathode of the Zener diode, and the power supply terminal of the control unit, respectively, while the anode of the TVS diode is used for grounding.

[0012] In one embodiment, the power supply unit further includes a first rectifier diode; The anode of the first rectifier diode is electrically connected to the positive output terminal of the rectifier unit and the input terminal of the switching transistor, respectively, and the cathode of the first rectifier diode is electrically connected to the cathode of the Zener diode and the power supply terminal of the control unit, respectively.

[0013] In one embodiment, the power supply unit further includes a second rectifier diode; The anode of the second rectifier diode is electrically connected to the cathode of the first rectifier diode and the cathode of the Zener diode, respectively, and the cathode of the second rectifier diode is electrically connected to the power supply terminal of the control unit.

[0014] Secondly, in one embodiment, the present invention provides a circuit breaker, which includes a trip unit and a current detection circuit as described in any of the above embodiments. The trip unit is connected in series with the circuit under test and electrically connected to the output terminal of the control unit. It is used to control the on / off state of the circuit under test under the control of the control unit.

[0015] By using the aforementioned current detection circuit and circuit breaker, and utilizing the existing leakage current transformer, corresponding current sampling units and phase sampling units are configured respectively, enabling the control unit to acquire the amplitude sampling signal and phase sampling signal corresponding to the current in the circuit under test, and to obtain the ground fault current in the circuit under test based on the amplitude sampling signal and phase sampling signal, thereby achieving ground fault protection. This utility model eliminates the need for an additional ground fault current transformer specifically for ground fault current detection, reducing the size and cost of the circuit breaker. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the current detection circuit in one embodiment of the present invention; Figure 2 This is a schematic diagram of the rectifier unit and the current sampling unit in one embodiment of the present invention; Figure 3 This is a schematic diagram of the phase sampling unit in one embodiment of the present invention; Figure 4 This is a schematic diagram of the rectifier unit and the power supply unit in one embodiment of the present invention; Figure 5 A circuit diagram showing that, in one embodiment of the present invention, the power supply unit further includes a TVS diode and a rectifier diode; Figure 6 This is a schematic diagram of the circuit breaker in one embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0019] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified. In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to implement and use this invention. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this invention can be implemented without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of this invention with unnecessary detail. Therefore, this invention is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0020] Firstly, such as Figure 1 As shown, in one embodiment, the present invention provides a current detection circuit, which includes a leakage current transformer, a rectifier unit, a current sampling unit, a phase sampling unit, and a control unit.

[0021] The specific structure of the leakage current transformer can be configured according to the circuit under test, for example in... Figure 1 In this embodiment, the circuit under test is specifically a three-phase four-wire circuit consisting of phases A, B, C, and N. Therefore, the leakage current transformer specifically includes mutual transformers A, B, C, and N, corresponding to phases A, B, C, and N, respectively. In other embodiments, the circuit under test can also be a three-phase three-wire circuit or a single-phase circuit.

[0022] Similarly, when the circuit under test adopts... Figure 1In the three-phase four-wire circuit shown, the rectifier unit specifically includes an A-phase rectifier unit, a B-phase rectifier unit, a C-phase rectifier unit, and an N-phase rectifier unit. The current sampling unit also specifically includes an A-phase current sampling unit, a B-phase current sampling unit, a C-phase current sampling unit, and an N-phase current sampling unit. The phase sampling unit also specifically includes an A-phase phase sampling unit, a B-phase phase sampling unit, a C-phase phase sampling unit, and an N-phase phase sampling unit.

[0023] Based on the above examples, in this case, the A-phase mutual inductor, A-phase rectifier unit, A-phase current sampling unit, and A-phase phase sampling unit correspond to each other; the B-phase mutual inductor, B-phase rectifier unit, B-phase current sampling unit, and B-phase phase sampling unit correspond to each other; the C-phase mutual inductor, C-phase rectifier unit, C-phase current sampling unit, and C-phase phase sampling unit correspond to each other; and the N-phase mutual inductor, N-phase rectifier unit, N-phase current sampling unit, and N-phase phase sampling unit correspond to each other.

[0024] The rectifier unit can use a bridge structure to achieve full-wave rectification or other structures to achieve half-wave rectification. The control unit includes, but is not limited to, an MCU (Micro Control Unit).

[0025] The leakage current transformer is electrically connected to the input terminal of the rectifier unit and the input terminal of the phase sampling unit, respectively, and is used to detect the current of the circuit under test and output the corresponding detection current.

[0026] The leakage current transformer converts a large current in the circuit under test into a small current through electromagnetic induction and outputs it as the detection current so that the subsequent units can perform relevant processing.

[0027] The output of the rectifier unit is electrically connected to the amplitude sampling input of the control unit through the current sampling unit. The current sampling unit is used to sample the current amplitude of the detection current after rectification by the rectifier unit and output the amplitude sampling signal to the control unit.

[0028] To eliminate the influence of AC on sampling, a corresponding rectifier unit needs to be installed before the current sampling unit. This rectifier unit rectifies the detection current output from the leakage current transformer, enabling the current sampling unit to directly sample the amplitude of the rectified detection current.

[0029] Normally, the control unit cannot directly sample the current amplitude of the current output by the rectifier unit. Therefore, the purpose of setting up a current sampling unit to sample the current amplitude is to output an amplitude sampling signal that meets the processing requirements of the control unit, so that the control unit can determine the amplitude of the detected current after obtaining the amplitude sampling signal.

[0030] The output of the phase sampling unit is electrically connected to the phase sampling input of the control unit, and is used to sample the current phase of the detected current and output a phase sampling signal to the control unit.

[0031] Among them, current phase sampling refers to sampling the phase angle of the detected current. However, the detected current after rectification by the rectifier unit cannot distinguish between the positive and negative half-cycles. Therefore, the phase sampling unit needs to be directly electrically connected to the leakage current transformer to achieve current phase sampling based on the AC detected current.

[0032] The control unit is used to obtain the ground fault current of the circuit under test based on the amplitude sampling signal and the phase sampling signal.

[0033] Among them, such as Figure 1 The three-phase four-wire circuit shown assumes that the amplitude of the current in phase A is I. A The amplitude of the B-phase current is I B The amplitude of the C-phase current is I C The amplitude of the N-phase current is I N If the phase angle of the A-phase current is α, the phase angle of the B-phase current is β, the phase angle of the C-phase current is γ, and the phase angle of the N-phase current is θ, then the real part of the ground fault current is Equation (1), the imaginary part of the ground fault current is Equation (2), and the ground fault current is Equation (3).

[0034] (1) (2) (3) By using the aforementioned current detection circuit and the existing leakage current transformer, corresponding current sampling units and phase sampling units are configured respectively, enabling the control unit to obtain the amplitude sampling signal and phase sampling signal corresponding to the current in the circuit under test. Based on the amplitude sampling signal and phase sampling signal, the ground fault current in the circuit under test can be obtained, and ground fault protection can be achieved accordingly. This invention eliminates the need for an additional ground fault current transformer specifically for ground fault current detection, thus reducing the size and cost of the circuit breaker.

[0035] In one embodiment, the current sampling unit includes a current sampling resistor and an amplification subunit. The negative output terminal of the rectifier unit is electrically connected to the input terminal of the amplification subunit and is used to ground through the current sampling resistor. The output terminal of the amplification subunit is electrically connected to the amplitude sampling input terminal of the control unit. The amplification subunit may include an amplitude sampling operational amplifier.

[0036] Among them, such as Figure 2As shown, taking phase A as an example, the phase A rectifier unit includes the phase A rectifier bridge BRA, the phase A current sampling unit includes the phase A current sampling resistor R1 and the phase A amplification subunit mainly composed of the phase A amplitude sampling operational amplifier U1A.

[0037] Specifically, the positive input terminal of the A-phase rectifier bridge BRA is electrically connected to the positive output terminal IA+ of the A-phase mutual inductor, and the negative input terminal of the A-phase rectifier bridge BRA is electrically connected to the negative output terminal IA- of the A-phase mutual inductor. The positive output terminal of the A-phase rectifier bridge BRA is used to output the power supply (such as a +12V power supply), and the negative output terminal of the A-phase rectifier bridge BRA is used to ground through the A-phase current sampling resistor R1 and connected to the A-phase amplitude sampling operational amplifier U1A through resistor R6, capacitor C1, and resistor R7. The inverting input terminal of the A-phase amplitude sampling operational amplifier U1A is electrically connected to the output terminal of the A-phase amplitude sampling operational amplifier U1A through resistor R5. The non-inverting input terminal of the A-phase amplitude sampling operational amplifier U1A is grounded through resistor R9. The output terminal of the A-phase amplitude sampling operational amplifier U1A is also electrically connected to the A-phase amplitude sampling input terminal of the control unit through resistor R8 and capacitor C2 to output the A-phase amplitude sampling signal IA_ADC to the control unit.

[0038] The A-phase amplitude sampling signal IA is amplified by the A-phase amplitude sampling operational amplifier U1A to obtain the A-phase amplitude sampling signal IA_ADC, which meets the signal processing requirements of the control unit.

[0039] After acquiring the A-phase amplitude sampling signal IA_ADC, the control unit can determine the amplitude of the A-phase current based on the amplification factor implemented by the A-phase amplitude sampling operational amplifier U1A, the resistance value of the A-phase current sampling resistor R1, the mapping relationship between the input and output of the A-phase rectifier bridge, and the mutual inductance parameters of the A-phase mutual inductors.

[0040] It is understandable that the B-phase current sampling unit, C-phase current sampling unit, and N-phase current sampling unit can adopt the same circuit structure, which will not be elaborated here.

[0041] In one embodiment, the phase sampling unit includes a phase sampling operational amplifier, the non-inverting input of which is electrically connected to the positive output of the leakage current transformer, the inverting input of which is grounded, and the output of which is electrically connected to the phase sampling input of the control unit.

[0042] Among them, such as Figure 3 As shown, taking phase A as an example, the phase A phase sampling unit includes phase A phase sampling operational amplifier U2A.

[0043] Specifically, the non-inverting input of phase A phase sampling operational amplifier U2A is electrically connected to the positive output terminal IA+ of phase A mutual inductor through resistor R28. The inverting input of phase A phase sampling operational amplifier U2A is electrically connected to the output terminal of phase A phase sampling operational amplifier U2A through resistor R25 and is used to ground through resistor R26. The output terminal of phase A phase sampling operational amplifier U2A is also electrically connected to the phase A phase sampling input terminal of the control unit through resistor R27 and capacitor C9 to output the phase A phase sampling signal Phase_A to the control unit.

[0044] If the voltage at the positive output terminal IA+ of transformer A is as follows:

[0045] The voltage corresponding to the A-phase sampling signal Phase_A is as follows:

[0046] This allows us to determine the starting point of the phase of the current in phase A, that is, to determine the phase angle of the current in phase A.

[0047] like Figure 1 As shown, in one embodiment, the current detection circuit further includes a power supply unit.

[0048] The input terminal of the power supply unit is electrically connected to the output terminal of the rectifier unit, and the output terminal of the power supply unit is electrically connected to the power supply terminal of the control unit.

[0049] The control unit requires a power supply to function properly. The rectifier unit can output a DC power supply based on the detection current output by the leakage current transformer. The power supply unit can process the amplitude of the DC power supply output by the rectifier unit to meet the power supply requirements of the control unit.

[0050] like Figure 4 As shown, in one embodiment, taking phase A as an example, the phase A rectifier unit includes the phase A rectifier bridge BRA, and the power supply unit includes a Zener diode D5, a pull-down resistor R41, a monitoring chip U3, and a switching transistor Q1.

[0051] The cathode of Zener diode D5 is electrically connected to the positive output terminal of phase A rectifier bridge BRA, the input terminal of switching transistor Q1, and the power supply terminal of the control unit, respectively, to connect to the initial power supply (e.g., +12V) and output the target power supply (e.g., +12V_D). The anode of Zener diode D5 is electrically connected to the input terminal VIN of monitoring chip U3 and is used to ground through pull-down resistor R41. The output terminal VOUT of monitoring chip U3 is electrically connected to the control terminal of switching transistor Q1, and the output terminal of switching transistor Q1 is used to ground.

[0052] The monitoring chip U3 is used to control the switching transistor Q1 to conduct when the Zener diode D5 is broken down.

[0053] Specifically, the switching transistor Q1 is an NMOS transistor. The voltage at the cathode of the Zener diode D5 can be represented by the potential +12V_T. When the potential +12V_T is higher than the preset voltage, the Zener diode D5 breaks down, and the capacitor C13 charges to input a high level to the input terminal VIN of the monitoring chip U3. This causes the output terminal VOUT of the monitoring chip U3 to input a high level to the control electrode of the switching transistor Q1 through resistors R42 and R43. Since the switching transistor Q1 is an NMOS transistor, it turns on, thus stopping the circuit. The target power supply (e.g., +12V_D) is stopped. Similarly, when the potential +12V_T is lower than the preset voltage, the Zener diode D5 is not broken down, and the capacitor C13 cannot be charged, so that a low level is input to the input terminal VIN of the monitoring chip U3. This causes the output terminal VOUT of the monitoring chip U3 to input a low level to the control terminal of the switching transistor Q1 through resistors R42 and R43. Since the switching transistor Q1 is an NMOS transistor, it is turned off, thereby outputting the target power supply (e.g., +12V_D).

[0054] like Figure 5 As shown, in one embodiment, the power supply unit further includes a TVS tube D4.

[0055] The cathode of TVS diode D4 is electrically connected to the positive output terminal of the rectifier unit (such as the positive output terminal of phase A rectifier bridge BRA), the input terminal of switching transistor Q1, the cathode of Zener diode D5, and the power supply terminal of the control unit. The anode of TVS diode D4 is used for grounding.

[0056] Among them, TVS diode D4 can be used for surge protection. When the voltage output of the A-phase rectifier bridge BRA suddenly increases, TVS diode D4 turns on, thereby short-circuiting the subsequent circuit and achieving the protection purpose.

[0057] like Figure 5 As shown, in one embodiment, the power supply unit further includes a first rectifier diode D2.

[0058] The anode of the first rectifier diode D2 is electrically connected to the positive output terminal of the rectifier unit (such as the positive output terminal of the A-phase rectifier bridge BRA) and the input terminal of the switching transistor Q1, respectively. The cathode of the first rectifier diode D2 is electrically connected to the cathode of the Zener diode D5 and the power supply terminal of the control unit, respectively.

[0059] The first rectifier diode D2 is used to rectify the voltage before the Zener diode D5, thereby improving the reliability of the power supply.

[0060] like Figure 5 As shown, in one embodiment, the power supply unit further includes a second rectifier diode D3.

[0061] The anode of the second rectifier diode D3 is electrically connected to the cathode of the first rectifier diode D2 and the cathode of the Zener diode D5, respectively. The cathode of the second rectifier diode D3 is electrically connected to the power supply terminal of the control unit.

[0062] The second rectifier diode D3 is used to rectify the voltage after the Zener diode D5, and also improves the reliability of the power supply.

[0063] Secondly, such as Figure 6 As shown, in one embodiment, the present invention provides a circuit breaker, which includes a trip unit and a current detection circuit as described in any of the above embodiments. The trip unit is connected in series with the circuit under test and electrically connected to the output terminal of the control unit. It is used to control the on / off state of the circuit under test under the control of the control unit.

[0064] By utilizing the current detection circuit included in the circuit breaker, and by configuring corresponding current sampling units and phase sampling units using the existing leakage current transformer, the control unit can acquire the amplitude sampling signal and phase sampling signal corresponding to the current in the circuit under test. Based on the amplitude sampling signal and phase sampling signal, the ground fault current in the circuit under test can be obtained, and ground fault protection can be achieved accordingly. This invention eliminates the need for an additional ground fault current transformer specifically for ground fault current detection, thus reducing the size and cost of the circuit breaker.

[0065] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.

[0066] The present invention provides a detailed description of a current detection circuit and circuit breaker. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, those skilled in the art will know that there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A current detection circuit, characterized in that, The current detection circuit includes a leakage current transformer, a rectifier unit, a current sampling unit, a phase sampling unit, and a control unit. The leakage current transformer is electrically connected to the input terminal of the rectifier unit and the input terminal of the phase sampling unit, respectively, and is used to detect the current of the circuit under test and output the corresponding detection current. The output terminal of the rectifier unit is electrically connected to the amplitude sampling input terminal of the control unit through the current sampling unit. The current sampling unit is used to sample the current amplitude of the detection current after rectification by the rectifier unit and output the amplitude sampling signal to the control unit. The output terminal of the phase sampling unit is electrically connected to the phase sampling input terminal of the control unit, and is used to sample the current phase of the detected current and output a phase sampling signal to the control unit. The control unit is used to obtain the ground fault current of the circuit under test based on the amplitude sampling signal and the phase sampling signal.

2. The current detection circuit according to claim 1, characterized in that, The current sampling unit includes a current sampling resistor and an amplification subunit; The negative output terminal of the rectifier unit is electrically connected to the input terminal of the amplifier subunit and is used to ground through the current sampling resistor. The output terminal of the amplifier subunit is electrically connected to the amplitude sampling input terminal of the control unit.

3. The current detection circuit according to claim 2, characterized in that, The amplification subunit includes an amplitude sampling operational amplifier; The inverting input terminal of the amplitude sampling operational amplifier is electrically connected to the negative output terminal of the rectifier unit, the non-inverting input terminal of the amplitude sampling operational amplifier is grounded, and the output terminal of the amplitude sampling operational amplifier is electrically connected to the amplitude sampling input terminal of the control unit.

4. The current detection circuit according to claim 1, characterized in that, The phase sampling unit includes a phase sampling operational amplifier; The non-inverting input of the phase sampling operational amplifier is electrically connected to the positive output of the leakage current transformer, the inverting input of the phase sampling operational amplifier is grounded, and the output of the phase sampling operational amplifier is electrically connected to the phase sampling input of the control unit.

5. The current detection circuit according to claim 1, characterized in that, The current detection circuit also includes a power supply unit; The input terminal of the power supply unit is electrically connected to the output terminal of the rectifier unit, and the output terminal of the power supply unit is electrically connected to the power supply terminal of the control unit.

6. The current detection circuit according to claim 5, characterized in that, The power supply unit includes a voltage regulator, a pull-down resistor, a monitoring chip, and a switching transistor; The cathode of the Zener diode is electrically connected to the positive output terminal of the rectifier unit, the input terminal of the switching transistor, and the power supply terminal of the control unit, respectively. The anode of the Zener diode is electrically connected to the input terminal of the monitoring chip and is used to ground through the pull-down resistor. The output terminal of the monitoring chip is electrically connected to the control terminal of the switching transistor, and the output terminal of the switching transistor is used to ground. The monitoring chip is used to control the switching transistor to conduct when the Zener diode is broken down.

7. The current detection circuit according to claim 6, characterized in that, The power supply unit also includes a TVS diode; The cathode of the TVS diode is electrically connected to the positive output terminal of the rectifier unit, the input terminal of the switching transistor, the cathode of the Zener diode, and the power supply terminal of the control unit, respectively, and the anode of the TVS diode is used for grounding.

8. The current detection circuit according to claim 6, characterized in that, The power supply unit also includes a first rectifier diode; The anode of the first rectifier diode is electrically connected to the positive output terminal of the rectifier unit and the input terminal of the switching transistor, respectively, and the cathode of the first rectifier diode is electrically connected to the cathode of the Zener diode and the power supply terminal of the control unit, respectively.

9. The current detection circuit according to claim 8, characterized in that, The power supply unit also includes a second rectifier diode; The anode of the second rectifier diode is electrically connected to the cathode of the first rectifier diode and the cathode of the Zener diode, respectively, and the cathode of the second rectifier diode is electrically connected to the power supply terminal of the control unit.

10. A circuit breaker, characterized in that, The circuit breaker includes a trip unit and a current detection circuit as described in any one of claims 1 to 9; The trip unit is connected in series with the circuit under test and electrically connected to the output terminal of the control unit, and is used to control the on / off state of the circuit under test under the control of the control unit.

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