Current transformer circuit and current transformer

Abstract

The present application discloses a current mutual induction circuit and a current mutual inductor, and relates to the technical field of current mutual induction. The present application discloses a current mutual induction circuit, comprising: an input shunt unit, the input shunt unit is connected to the output end of the circuit to be measured, the input shunt unit is used to receive the input current of the circuit to be measured, and shunt the input current to obtain a mutual induction input current; a current mutual induction unit, the input end of the current mutual induction unit is connected to the input shunt unit and the output end of the circuit to be measured, the current mutual induction unit is used to perform mutual induction sampling based on the mutual induction input current to obtain a sampled output current; a mutual induction output unit, the mutual induction output unit is connected to the output end of the current mutual induction unit and a collection device, and the mutual induction output unit is used to output the sampled output current to the collection device. The present application reduces the cost of current mutual induction.

Description

Technical Field

[0001] The present application relates to the technical field of current mutual induction, and in particular to a current mutual induction circuit and a current mutual induction device. Background Art

[0002] With the development of optocouplers, users have also put forward higher requirements for current mutual inductance.

[0003] As the collected current increases, the volume of the magnetic core or coil in the traditional current transformer needs to be increased to achieve the effect of collecting a larger current. This type of current transformer will result in high cost of the current transformer due to the need to increase the volume of the magnetic core or coil in the current transformer.

[0004] The above contents are only used to assist in understanding the technical solution of the present application and do not constitute an admission that the above contents are prior art. Utility Model Content

[0005] The main purpose of the present application is to provide a current mutual induction circuit and a current mutual inductor, aiming to solve the technical problem of high cost of current mutual induction.

[0006] To achieve the above object, the present application provides a current mutual induction circuit, the current mutual induction circuit comprising:

[0007] An input shunt unit, the input shunt unit is connected to the output end of the circuit to be tested, the input shunt unit is used to receive the input current of the circuit to be tested, and shunt the input current to obtain a mutual inductance input current;

[0008] A current mutual induction unit, the input end of which is connected to the input shunt unit and the output end of the circuit to be tested, and the current mutual induction unit is used to perform mutual induction sampling based on the mutual induction input current to obtain a sampled output current;

[0009] A mutual inductance output unit, wherein the mutual inductance output unit is connected to an output end of the current mutual inductance unit and a collection device, and the mutual inductance output unit is used to output the sampled output current to the collection device.

[0010] In one embodiment, the output end of the circuit under test includes a first output end and a second output end, and the input current splitting unit includes:

[0011] A plurality of shunt resistors, wherein a first end of each shunt resistor is connected to the first output end, and a second end of each shunt resistor is connected to the second output end.

[0012] In one embodiment, the input split unit further includes a multi-terminal selector and a control chip, wherein the multi-terminal selector is provided with a multi-terminal input terminal, a plurality of multi-terminal output terminals and a multi-terminal control terminal:

[0013] The multi-terminal input terminal is connected to the first output terminal, each of the multi-terminal output terminals is connected to a first terminal of the shunt resistor, and the multi-terminal control terminal is connected to the control chip, or;

[0014] The multi-terminal input end is connected to the second output end, each of the multi-terminal output ends is connected to a second end of the shunt resistor, and the multi-terminal control end is connected to the control chip.

[0015] In one embodiment, the multi-terminal output terminal includes a first control state terminal and a second control state terminal:

[0016] The multi-terminal input terminal is connected to the first control state terminal, and the multi-terminal input terminal is disconnected from the second control state terminal, or;

[0017] The multi-terminal input terminal is connected to the second control state terminal, and the multi-terminal input terminal is disconnected from the first control state terminal.

[0018] In one embodiment, the input shunt unit further includes a plurality of two-to-one selectors and a control chip, wherein the two-to-one selector is provided with a selection input terminal, a first selection output terminal, a second selection output terminal and a selection control terminal:

[0019] The selection input terminal is connected to the first output terminal, each of the first selection output terminals is connected to the first terminal of the shunt resistor, each of the second selection output terminals is suspended, and the selection control terminal is connected to the control chip, or;

[0020] The selection input terminal is connected to the second output terminal, each of the first selection output terminals is connected to the second end of the shunt resistor, each of the second selection output terminals is suspended, and the selection control terminal is connected to the control chip.

[0021] In one embodiment, the selection input terminal is connected to the first selection output terminal, and the selection input terminal is disconnected from the second selection output terminal, or;

[0022] The selection input terminal is connected to the second selection output terminal, and the selection input terminal is disconnected from the first selection output terminal.

[0023] In one embodiment, the acquisition device includes a first input terminal and a second input terminal, and the current mutual inductance unit includes a transformer, and the transformer includes:

[0024] An input coil, a first end of the input coil is connected to the first output end, and a second end of the input coil is connected to the second output end;

[0025] A magnetic core, the magnetic core being wound around the input coil;

[0026] An output coil, wherein a first end of the output coil is connected to the first input end, and a second end of the output coil is connected to the second input end, wherein the output coil is wound on the magnetic core.

[0027] In one embodiment, the first end of the input coil is a terminal of a different name, and the second end of the input coil is a terminal of the same name, or the first end of the input coil is a terminal of the same name, and the second end of the input coil is a terminal of a different name.

[0028] In one embodiment, the mutual inductance output unit includes:

[0029] an output resistor, a first end of the output resistor and a first end of the output coil, and a second end of the output resistor and a second end of the output coil.

[0030] In addition, to achieve the above-mentioned purpose, the present application also provides a current transformer, which includes the above-mentioned current transformer circuit.

[0031] The embodiment of the present application provides a current mutual induction circuit, comprising an input shunt unit, the input shunt unit is connected to the output end of the circuit to be tested, the input shunt unit is used to receive the input current of the circuit to be tested, and shunt the input current to obtain a mutual induction input current; a current mutual induction unit, the input end of the current mutual induction unit is connected to the input shunt unit and the output end of the circuit to be tested, the current mutual induction unit is used to perform mutual induction sampling based on the mutual induction input current to obtain a sampled output current; a mutual induction output unit, the mutual induction output unit is connected to the output end of the current mutual induction unit and a collection device, the mutual induction output unit is used to output the sampled output current to the output end of the current mutual induction unit The output current is output to the acquisition device, and the input current of the circuit to be tested is received through the input shunt unit, and the input current is shunted to obtain the mutual inductance input current. At this time, the mutual inductance input current can be directly sampled based on the current mutual inductance unit to obtain the sampled output current, so there is no need to increase the volume of the magnetic core or coil in the current transformer (changing the magnetic core or coil requires complex processes, and the components corresponding to the magnetic core or coil need to be directly replaced to achieve the change). Then, the input current is shunted through the input shunt unit to obtain the mutual inductance input current, and the sampled output current can be directly obtained based on the current mutual inductance unit. The cost of the current mutual inductance is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the framework of the first embodiment of the current mutual induction circuit of the present application;

[0033] Figure 2 A circuit diagram of a commonly used current mutual inductance circuit;

[0034] Figure 3 A circuit diagram of a first embodiment of a current mutual induction circuit of the present application;

[0035] Figure 4 A circuit diagram of a second embodiment of the current mutual induction circuit of the present application;

[0036] Figure 5 A circuit diagram of a third embodiment of the current mutual induction circuit of the present application;

[0037] Figure 6 A schematic diagram of a usage scenario of the current mutual inductance circuit of the present application.

[0038] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings.

[0039] Description of Figure Numbers:

[0040] 100, circuit to be tested; 10, input shunt unit; 20, current mutual inductance unit; 30, mutual inductance output unit; 200, acquisition device; 110, first output terminal; 120, second output terminal; R1, shunt resistor;

[0041] L1, input coil; L2, output coil; CX, magnetic core; R2, output resistor; 210, first input terminal; 220, second input terminal; 11, multi-terminal selector; 12, control chip; 13, two-to-one selector; 111, multi-terminal input terminal; 112, multi-terminal output terminal; 113, multi-terminal control terminal; 131, selection input terminal; 132, first selection output terminal; 133, second selection output terminal; 134, selection control terminal; 300, current transformer. DETAILED DESCRIPTION

[0042] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0043] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0044] In the current test circuit, an isolated circuit transformer or Hall device is required. As the measured current increases, the volume and wire diameter of the transformer will continue to increase, and the corresponding cost will also increase (based on the actual acquisition principle, it can be known that the actual increase is the volume of the magnetic core and the number of coils inside the transformer). Because the existing transformer uses the transformer ratio to complete the current sampling, refer to Figure 2 , Figure 2This is a circuit diagram of a commonly used current mutual inductance circuit. When current flows through the coil, according to the transformer current conservation law, the current relationship is I1 / I2=N2 / N1. For example, here N1:N2=1:100, then I1:I2=100:1. At this time, when 10A passes through N1, the current of N1 is 10 / 100=0.1A, that is, when the output resistance R=33R, the voltage is 33*0.1=3.3V.

[0045] At this time, when the current flows through the line, heat will be generated due to the built-in wire. N1 and N2 are designed according to the existing parameters. When the current exceeds the current, it will burn out due to excessive stability. Secondly, since the cross-section of the core is certain, when the current is too high, according to the law of electromagnetic induction, LI=NФ, and because the primary and secondary inductances L and the number of turns N are fixed, the current and Φ are proportional, and Φ=B*AB is the magnetic flux density, A is the area, and the area is also unchanged, then the current I is proportional to the magnetic flux density B. When the current increases, it will exceed the original designed magnetic flux density, causing the core to saturate. After the core is saturated, the magnetic failure will cause the normal current transmission to fail and the current mutual inductance function will be lost. Based on the above problems, the common solution is to redesign the turns ratio of the transformer, increase the input wire diameter and increase the volume of the core. The volume and material costs increase, and the new device increases the material types. At the same time, the turns ratio of the transformer needs to be replaced in real time, which is difficult.

[0046] Therefore, based on the shortcomings of the above current mutual inductance circuits, a current mutual inductance circuit of the present application is proposed. The main solution of the embodiment of the present application is: receiving the input current of the circuit to be tested through an input shunt unit, and shunting the input current to obtain a mutual inductance input current. At this time, the mutual inductance input current can be directly sampled based on the current mutual inductance unit to obtain a sampled output current, thereby eliminating the need to increase the volume of the magnetic core or coil in the current transformer (changing the magnetic core or coil requires a complex process, and the components corresponding to the magnetic core or coil need to be directly replaced to achieve the change). Furthermore, the input current is shunted through the input shunt unit to obtain a mutual inductance input current, and the sampled output current can be directly obtained based on the current mutual inductance unit through mutual inductance sampling, thereby reducing the cost of the current mutual inductance.

[0047] Based on this, the embodiment of the present application provides a current mutual induction circuit, referring to Figure 1 , Figure 1 This is a schematic diagram of the framework of the first embodiment of the current mutual inductance circuit of the present application.

[0048] Reference Figure 1 , the present application provides a current mutual induction circuit, the current mutual induction circuit comprising:

[0049] An input shunt unit 10, the input shunt unit 10 is connected to the output end of the circuit under test 100, the input shunt unit 10 is used to receive the input current of the circuit under test 100, and shunt the input current to obtain a mutual inductance input current;

[0050] A current mutual inductance unit 20, wherein the input end of the current mutual inductance unit 20 is connected to the input shunt unit 10 and the output end of the circuit to be tested 100, and the current mutual inductance unit 20 is used to perform mutual inductance sampling based on the mutual inductance input current to obtain a sampled output current;

[0051] The mutual inductance output unit 30 is connected to the output end of the current mutual inductance unit 20 and the acquisition device 200 . The mutual inductance output unit 30 is used to output the sampled output current to the acquisition device 200 .

[0052] In this embodiment, the input current of the circuit to be tested 100 is received by the input shunt unit 10, and the input current is shunted to obtain the mutual inductance input current, wherein the circuit to be tested 100 may be a circuit or instrument for current acquisition, the input current refers to the current output by the circuit to be tested 100, and because it is actually an input current mutual inductance circuit, it is also called the input current, and the mutual inductance input current refers to the current obtained after the input current is shunted, thereby reducing the current value received by the current mutual inductance unit 20 in the input current mutual inductance circuit, thereby protecting the current mutual inductance unit 20 while realizing the acquisition of large current at low cost, and the common method is to directly modify the characteristics of the entire circuit, such as the current bearing capacity of the current mutual inductance unit 20 (increasing the coil and core volume of the transformer in the current mutual inductance unit 20). By using the input shunt unit 10, the acquisition of large current can be realized at low cost without replacing the transformer in the current mutual inductance unit 20, thereby greatly reducing the cost of current mutual inductance when acquiring large current.

[0053] In one embodiment, after the mutual inductance input current is obtained, the mutual inductance input current is sampled based on the current mutual inductance unit 20 to obtain the sampled output current, which can be as follows: Figure 2 The transformer mutual inductance method introduced in the above description will be based on the mutual inductance output unit 30 for outputting the sampled output current to the acquisition device 200. The sampled output current refers to the current obtained after the mutual inductance sampling by the current mutual inductance unit 20. The acquisition device 200 can be a host computer or other equipment, which is not limited here. Finally, the input current of the circuit to be tested 100 can be determined based on the sampled output current, the mutual inductance sampling ratio in the current mutual inductance unit 20, and the shunt ratio in the input shunt unit 10, thereby realizing the current acquisition at high current at low cost.

[0054] Further, based on the above-mentioned first embodiment of the present application, a second embodiment of the current mutual inductance circuit of the present application is proposed, referring to Figure 3 , Figure 3 This is a circuit diagram of the first embodiment of the current mutual inductance circuit of the present application. The output end 100 of the circuit to be tested includes a first output end 110 and a second output end 120. The input current dividing unit 10 includes:

[0055] A plurality of shunt resistors R1 , wherein a first end of each shunt resistor R1 is connected to the first output end 110 , and a second end of each shunt resistor R1 is connected to the second output end 120 .

[0056] In this embodiment, the current mutual inductance circuit still uses the existing mutual inductance circuit (no need to increase the wire diameter and volume of the magnetic core and coil in the internal transformer), that is, no re-proofing is required. By designing multiple parallel shunt resistors R1 between the first output terminal 110 and the second output terminal 120, when the current is greater than the mutual inductance current, the input between the first output terminal 110 and the second output terminal 120 is shunted and then collected. At this time, the corresponding shunt resistor R1 position can be directly reserved on the PCB. For example, if the mutual inductance is 0.8mΩ, then 9 0.8mΩ resistors need to be added if 100A is required to be measured. In this way, I=U / R. Since the voltage and resistance are the same, each resistor will flow through the same current. At this time, the mutual inductance only flows through 1 / 10 of the total current. When the current is 100A, the mutual inductor is working within the normal parameter range. Finally, the software sampling needs to add the divided current multiples to restore the test parameters, thereby solving the problem of large current collection from different angles.

[0057] In one embodiment, the shunt resistor R1 can use a commonly used constant resistor, a variable resistor, or a resistor, which is not limited here. For example, the number of resistors connected to the circuit can be selected according to actual conditions (generally speaking, the larger the collection current, the more resistors need to be connected in parallel) or the resistance value (the higher the resistance value accuracy, the higher the collection accuracy).

[0058] In one embodiment, referring to Figure 4 , Figure 4 This is a circuit diagram of a second embodiment of the current mutual inductance circuit of the present application. The input current splitting unit 10 further includes a multi-terminal selector 11 and a control chip 12. The multi-terminal selector 11 is provided with a multi-terminal input terminal 111, a plurality of multi-terminal output terminals 112 and a multi-terminal control terminal 113:

[0059] The multi-terminal input terminal 111 is connected to the first output terminal 110, each of the multi-terminal output terminals 212 is connected to a first terminal of the shunt resistor R1, and the multi-terminal control terminal 213 is connected to the control chip 22, or;

[0060] The multi-terminal input terminal 211 is connected to the second output terminal 120 , each of the multi-terminal output terminals 112 is connected to a second terminal of the shunt resistor R1 , and the multi-terminal control terminal 113 is connected to the control chip 12 .

[0061] Specifically, the multi-terminal output terminal 112 includes a first control state terminal and a second control state terminal:

[0062] The multi-terminal input terminal 111 is connected to the first control state terminal, and the multi-terminal input terminal 111 is disconnected from the second control state terminal, or;

[0063] The multi-terminal input terminal 111 is connected to the second control state terminal, and the multi-terminal input terminal 111 is disconnected from the first control state terminal.

[0064] In this embodiment, in order to ensure that the number of shunt resistors R1 connected to the current mutual inductance circuit is adjustable, a multi-terminal selector 11 and a control chip 12 can be directly connected, and then the multi-terminal input terminal 111 of the multi-terminal selector 11 is controlled by the control chip 12 to be connected to a part or all of the multi-terminal output terminals 212, so as to realize that a part or all of the shunt resistors R1 are connected in parallel to the second output terminal 120 and the first output terminal 110. Among them, the first control state terminal and the second control state terminal are ports for controlling the connection or disconnection of the multi-terminal output terminal 112 and the multi-terminal input terminal 111. At this time, multiple switches can also be directly connected to the shunt resistor R1 for selection. It is worth noting that the control method can be that the control chip 12 inputs 00111, then the first and second multi-terminal output terminals 212 are connected to the multi-terminal input terminal 111, and the third to fifth multi-terminal output terminals 212 are disconnected from the multi-terminal input terminal 111. The above is only one of the connection methods, and other connection methods can also be used, which are not limited here.

[0065] Further, based on the first embodiment and / or the second embodiment of the present application, a third embodiment of the current mutual induction circuit of the present application is proposed, referring to Figure 5 , Figure 5 This is a circuit diagram of a third embodiment of the current mutual inductance circuit of the present application. The input shunt unit 10 further includes a plurality of two-to-one selectors 13 and a control chip 12. The two-to-one selector 13 is provided with a selection input terminal 131, a first selection output terminal 131, a second selection output terminal 133 and a selection control terminal 134:

[0066] The selection input terminal 131 is connected to the first output terminal 110, each of the first selection output terminals 132 is connected to a first end of the shunt resistor R1, each of the second selection output terminals 133 is suspended, and the selection control terminal 134 is connected to the control chip 12, or;

[0067] The selection input terminal 131 is connected to the second output terminal 120 , each of the first selection output terminals 132 is connected to the second end of the shunt resistor R1 , each of the second selection output terminals 133 is suspended, and the selection control terminal 134 is connected to the control chip 12 .

[0068] Specifically, the selection input terminal 131 is connected to the first selection output terminal 132, and the selection input terminal 131 is disconnected from the second selection output terminal 133, or;

[0069] The selection input terminal 131 is connected to the second selection output terminal 133 , and the selection input terminal 131 is disconnected from the first selection output terminal 132 .

[0070] In this embodiment, in order to ensure that the number of shunt resistors R1 connected to the current mutual inductance circuit is adjustable, multiple two-to-one selectors 13 and control chips 12 can be directly connected, and then the selection input terminal 131 of the two-to-one selector 13 is controlled by the control chip 12 to connect to the first selection output terminal 131 or the second selection output terminal 133, so as to achieve that part or all of the shunt resistors R1 are connected in parallel to the second output terminal 120 and the first output terminal 110. That is, the selection input terminal 131 is connected to the first output terminal 132, and the selection input terminal 131 is disconnected from the second output terminal 133. At this time, the shunt resistor R1 connected to the first output terminal 132 is connected between the second output terminal 120 and the first output terminal 110. If the selection input terminal 131 is connected to the second output terminal 133, the selection input terminal 131 is disconnected from the first output terminal 132. At this time, the shunt resistor R1 connected to the first output terminal 132 is not connected between the second output terminal 120 and the first output terminal 110. Furthermore, it is possible to adaptively connect different numbers of shunt resistors R1 to achieve current collection of different magnitudes at a low cost.

[0071] In one embodiment, the above selection method may not be set, and multiple pluggable interfaces may be directly set between the second output terminal 120 and the first output terminal 110. When the user needs a certain value and number of shunt resistors R1, the tubes of the shunt resistors R1 can be directly inserted into the pluggable interfaces, thereby greatly improving the scalability of the control.

[0072] In one embodiment, the acquisition device 200 includes a first input terminal 210 and a second input terminal 220, and the current mutual inductance unit 30 includes a transformer, and the transformer includes:

[0073] An input coil L1, wherein a first end of the input coil L1 is connected to the first output end 110, and a second end of the input coil L1 is connected to the second output end 120;

[0074] A magnetic core CX, the magnetic core CX is wound around the input coil L1;

[0075] An output coil L2, wherein a first end of the output coil L2 is connected to the first input end 210, and a second end of the output coil L2 is connected to the second input end 220, wherein the output coil L2 is wound on the magnetic core CX.

[0076] Specifically, the first end of the input coil L1 is a terminal of different names, and the second end of the input coil L1 is a terminal of the same name, or the first end of the input coil L1 is a terminal of the same name, and the second end of the input coil L1 is a terminal of different names.

[0077] Specifically, the mutual inductance output unit 30 includes:

[0078] an output resistor R2, a first end of the output resistor R2 and a first end of the output coil L2, and a second end of the output resistor R2 and a second end of the output coil L2.

[0079] In this embodiment, the current mutual inductance unit 30 includes a transformer, and the current is collected based on the current sensing method of the transformer. The use of the above transformer and the related parameter settings are consistent with the commonly used transformers for collecting current, and are not limited here. Finally, the current collection is completed by outputting the output coil L2 to the output resistor R2 in the mutual inductance output unit 30. At this time, the input current of the circuit to be tested 100 can be determined based on the collected value, the transformer mutual inductance sampling ratio and the shunt situation, thereby realizing the current collection of large currents at a low cost. Figure 6 , Figure 6 This is a schematic diagram of a usage scenario of the current transformer circuit of the present application. The circuit to be tested 100 and the acquisition device 200 are directly connected through the current transformer 300 to complete the current acquisition of the circuit to be tested 100 by the acquisition device 200 through the current transformer 300. At this time, there is no need to consider the current size of the circuit to be tested 100 (different resistance values ​​and quantities of resistors in the input shunt unit 10 are selected for different current sizes), and there is no need to replace the transformer in the current transformer unit 20, which can greatly reduce the cost of current mutual induction when collecting large currents.

[0080] The present application also provides a current transformer 300, comprising the above-mentioned current transformer circuit.

[0081] The current transformer provided by the present application can solve the technical problem of high cost of current transformer. Compared with the prior art, the beneficial effects of the current transformer provided by the present application are the same as the beneficial effects of the current transformer circuit provided by the above embodiment, which will not be repeated here.

[0082] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A current mutual inductance circuit, characterized in that: The current mutual induction circuit comprises: An input shunt unit, the input shunt unit is connected to the output end of the circuit to be tested, the input shunt unit is used to receive the input current of the circuit to be tested, and shunt the input current to obtain a mutual inductance input current; A current mutual induction unit, the input end of which is connected to the input shunt unit and the output end of the circuit to be tested, and the current mutual induction unit is used to perform mutual induction sampling based on the mutual induction input current to obtain a sampled output current; A mutual inductance output unit, wherein the mutual inductance output unit is connected to an output end of the current mutual inductance unit and a collection device, and the mutual inductance output unit is used to output the sampled output current to the collection device.

2. The current mutual induction circuit according to claim 1, characterized in that: The output end of the circuit to be tested includes a first output end and a second output end, and the input current dividing unit includes: A plurality of shunt resistors, wherein a first end of each shunt resistor is connected to the first output end, and a second end of each shunt resistor is connected to the second output end.

3. The current mutual induction circuit according to claim 2, characterized in that: The input shunt unit further includes a multi-terminal selector and a control chip, wherein the multi-terminal selector is provided with a multi-terminal input terminal, a plurality of multi-terminal output terminals and a multi-terminal control terminal: The multi-terminal input terminal is connected to the first output terminal, each of the multi-terminal output terminals is connected to a first terminal of the shunt resistor, and the multi-terminal control terminal is connected to the control chip, or; The multi-terminal input end is connected to the second output end, each of the multi-terminal output ends is connected to a second end of the shunt resistor, and the multi-terminal control end is connected to the control chip.

4. The current mutual induction circuit according to claim 3, characterized in that: The multi-terminal output terminal includes a first control state terminal and a second control state terminal: The multi-terminal input terminal is connected to the first control state terminal, and the multi-terminal input terminal is disconnected from the second control state terminal, or; The multi-terminal input terminal is connected to the second control state terminal, and the multi-terminal input terminal is disconnected from the first control state terminal.

5. The current mutual induction circuit according to claim 2, characterized in that: The input shunt unit further includes a plurality of two-to-one selectors and a control chip, wherein the two-to-one selector is provided with a selection input terminal, a first selection output terminal, a second selection output terminal and a selection control terminal: The selection input terminal is connected to the first output terminal, each of the first selection output terminals is connected to the first terminal of the shunt resistor, each of the second selection output terminals is suspended, and the selection control terminal is connected to the control chip, or; The selection input terminal is connected to the second output terminal, each of the first selection output terminals is connected to the second end of the shunt resistor, each of the second selection output terminals is suspended, and the selection control terminal is connected to the control chip.

6. The current mutual induction circuit according to claim 5, characterized in that: The selection input terminal is connected to the first selection output terminal, and the selection input terminal is disconnected from the second selection output terminal, or; The selection input terminal is connected to the second selection output terminal, and the selection input terminal is disconnected from the first selection output terminal.

7. The current mutual induction circuit according to claim 2, characterized in that: The acquisition device includes a first input terminal and a second input terminal, and the current mutual inductance unit includes a transformer, and the transformer includes: An input coil, a first end of the input coil is connected to the first output end, and a second end of the input coil is connected to the second output end; A magnetic core, the magnetic core being wound around the input coil; An output coil, wherein a first end of the output coil is connected to the first input end, and a second end of the output coil is connected to the second input end, wherein the output coil is wound on the magnetic core.

8. The current mutual induction circuit according to claim 7, characterized in that: The first end of the input coil is a terminal of a different name, and the second end of the input coil is a terminal of the same name, or the first end of the input coil is a terminal of the same name, and the second end of the input coil is a terminal of a different name.

9. The current mutual induction circuit according to claim 8, characterized in that: The mutual inductance output unit comprises: an output resistor, a first end of the output resistor and a first end of the output coil, and a second end of the output resistor and a second end of the output coil.

10. A current transformer, characterized in that: The current transformer comprises the current transformer circuit according to any one of claims 1 to 9.

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