A step-type copper busbar current detection device

Abstract

The embodiment of the present invention discloses a step-type copper busbar current detection device, which includes: a circuit board, a magnetic induction module and a step-type copper busbar, the magnetic induction module includes a first magnetic induction unit and a second magnetic induction unit, the side of the step-type copper busbar facing the magnetic induction module includes different first steps and second steps, the first magnetic induction unit is located above the first step, and the second magnetic induction unit is located above the second step; the current to be measured flows through a cross section perpendicular to the step-type copper busbar, the first magnetic induction unit and the second magnetic induction unit sense the differential mode magnetic field generated by the current to be measured flowing through the step-type copper busbar in a differential manner, and generate a differential voltage signal and output it. The current detection device provided by the embodiment of the present invention has the characteristics of adjustable common mode magnetic field working point, applicable to a variety of magnetic induction units, adjustable sensitivity, input and output electrical isolation, strong anti-common mode interference capability, and can measure AC and DC currents and large currents.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of electrical quantity measurement, and in particular to a step-type copper busbar current detection device. Background Art

[0002] Current detection devices are widely used in industrial automation technology, detection technology, power monitoring systems, inverter power supplies, electric vehicles, etc. At present, commonly used current detection devices include shunts based on copper bars to realize signal input, current transformers and Rogowski coils based on the principle of electromagnetic induction, optical fiber current sensors, and magnetic current sensors that use conductive materials to generate magnetic fields to input magnetic induction elements.

[0003] The shunt is made based on the principle that voltage is generated across a resistor when a DC current passes through it. It is essentially a resistor with a very small resistance value, which directly applies Ohm's law to convert the current signal into a voltage signal. There is an electrical connection between the measured current loop and the measurement loop of the shunt, and there is no electrical isolation between the signal output end and the measured current loop, which causes mutual interference between the two. It is suitable for low frequency and low power, cannot measure the current of high voltage loops, and is also difficult to measure large AC currents.

[0004] Current transformers are based on the principle of electromagnetic induction and can only measure changing currents. Closed-type current transformers require the busbar to be removed before installation or disassembly, and have a complex structure; the magnetic circuit of open-type current transformers has an air gap, which makes the product itself have a relatively large error and a large size. Rogowski coils are similar to current transformers, with an air core design that can be directly put on the conductor to be measured. They are suitable for measuring AC currents in a wide frequency range, but cannot measure DC currents. They have low sensitivity and are large in size.

[0005] The functional fiber optic sensor in the fiber optic current sensor is based on the Faraday effect of magneto-optical crystals. It uses optical fiber that is sensitive to and capable of detecting external information as a sensing element. It has high measurement accuracy and is easy to miniaturize, but it must use special optical fibers, which is costly.

[0006] Magnetic current sensors use different structural designs of current-carrying conductor materials to generate a magnetic field in space, and then use various magnetic induction elements to sense this magnetic field and output a voltage signal to detect the current. Interference has a great impact on the accuracy of current measurement, and the anti-interference ability of magnetic current sensors can be improved to achieve the effect of improving their current measurement accuracy. The anti-interference ability of existing magnetic current sensors is generally designed to use the difference in magnetic fields generated by current-carrying conductors at different positions in space, and perform differential tests on the magnetic field through magnetic induction elements.

[0007] The current measurement realized in differential mode includes: (1) a current detection method using two magnetic induction elements to differentially sense the magnetic field inside the same annular iron core; however, there is a magnetic leakage problem in the air gap of the iron core and the volume and weight of the magnetic ring structure are large. Since the magnetic lines of force inside the same annular iron core directly pass through the magnetic induction unit, it is difficult to adjust the common-mode magnetic field working point and the input signal range. When measuring large currents, the magnetic induction unit is easily saturated; (2) using U-shaped wires to generate differential signals in opposite directions, or using a copper bar with a neck depression as a signal input, or using a copper busbar wire to be measured with a rectangular or rounded rectangular cross-section as a signal input; however, when the current is large, the magnetic field generated by the current to be measured passing through the above wires is directly used as the input signal of the differential detection magnetoresistive sensitive element. Therefore, when measuring large currents, the common-mode magnetic field will saturate the magnetoresistive sensor chip, resulting in a limited input range. Summary of the invention

[0008] The embodiment of the present invention provides a stepped copper busbar current detection device to solve the problem of limited measurement accuracy and measurement range of existing current sensors.

[0009] An embodiment of the present invention provides a stepped copper busbar current detection device, comprising:

[0010] Circuit board,

[0011] A magnetic induction module fixed on the circuit board, the magnetic induction module at least comprising a first magnetic induction unit and a second magnetic induction unit, the first magnetic induction unit and the second magnetic induction unit are located on the same horizontal plane, and the horizontal plane is parallel to the plane where the circuit board is located;

[0012] A stepped copper busbar, wherein a side of the stepped copper busbar facing the magnetic induction module is stepped, the stepped copper busbar comprises at least a first step and a second step different from the first step, in a direction perpendicular to the circuit board, the first magnetic induction unit is located above the first step, and the second magnetic induction unit is located above the second step, and the stepped copper busbar is electrically isolated from the magnetic induction module;

[0013] The current to be measured flows through a cross section perpendicular to the stepped copper busbar, and the first magnetic induction unit and the second magnetic induction unit differentially sense the differential mode magnetic field generated by the current to be measured flowing through the stepped copper busbar, and generate and output a differential voltage signal.

[0014] The embodiment of the present invention further provides a step-type copper busbar current detection device, comprising: a step-type copper busbar, a shunt copper busbar, a magnetic induction module and a circuit board, wherein the magnetic induction module is fixed on the circuit board;

[0015] The stepped copper busbar and the shunt copper busbar are connected in series and parallel to form a current input module to be measured, the magnetic induction module and the circuit board form a signal output module, and the current input module to be measured is electrically isolated from the signal output module;

[0016] The side of the stepped copper busbar facing the magnetic induction module is stepped, and the stepped copper busbar comprises at least a first step and a second step;

[0017] The magnetic induction module at least includes a first magnetic induction unit and a second magnetic induction unit, the first magnetic induction unit and the second magnetic induction unit are located on the same horizontal plane, and the horizontal plane is parallel to the plane where the circuit board is located, in a direction perpendicular to the circuit board, the first magnetic induction unit is located above the first step, and the second magnetic induction unit is located above the second step;

[0018] The current to be measured flows through a cross section perpendicular to the stepped copper busbar and the shunt copper busbar, and generates a magnetic field at the position of the magnetic induction module; the first magnetic induction unit and the second magnetic induction unit differentially sense the magnetic field generated by the current to be measured flowing through the current to be measured input module, and generate a voltage signal, which forms an output signal of the stepped copper busbar current detection device.

[0019] In the step-type copper busbar current detection device provided by the embodiment of the present invention, the step-type copper busbar has a first step and a second step with a height difference, and the magnetic induction unit in the magnetic induction module senses the differential mode magnetic field generated by the height difference between the first step and the second step in a differential manner; since the cross-sectional current density of the step-type copper busbar is the same, by adjusting the height of the first step and the second step, most of the current to be measured can flow through the lower rectangle of the step-type copper busbar away from the magnetic induction module and form a common mode magnetic field, and at the same time, the size of the differential mode magnetic field can be adjusted and controlled to expand the measurement current range. The step-type copper busbar current detection device has the characteristics of adjustable common mode magnetic field working point, applicable to a variety of magnetic induction units, adjustable sensitivity, input and output electrical isolation, strong anti-common mode interference capability, and can measure AC and DC currents and large currents. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, although the drawings described below are some specific embodiments of the present invention, for those skilled in the art, the basic concepts of the device structure, driving method and manufacturing method disclosed and suggested by the various embodiments of the present invention can be expanded and extended to other structures and drawings, and there is no doubt that these should be within the scope of the claims of the present invention.

[0021] Figure 1 is a schematic diagram of a step-type copper busbar current detection device provided by an embodiment of the present invention;

[0022] Figure 2 yes Figure 1 The magnetic field simulation diagram of the step-type copper busbar current detection device shown;

[0023] Figure 3 yes Figure 1 The schematic diagram of the bridge structure of the step-type copper busbar current detection device shown;

[0024] Figure 4 It is a schematic diagram of a voltage-magnetic field curve of a current detection device of a magnetoresistive sensitive element;

[0025] Figure 5 is a schematic diagram of another step-type copper busbar current detection device provided by an embodiment of the present invention;

[0026] Figure 6 yes Figure 5 The magnetic field simulation diagram of the step-type copper busbar current detection device shown;

[0027] Figure 7 yes Figure 5 The schematic diagram of the bridge structure of the step-type copper busbar current detection device shown;

[0028] Figure 8 is a schematic diagram of another step-type copper busbar current detection device provided by an embodiment of the present invention;

[0029] Fig. 9 yes Figure 8 The magnetic field simulation diagram of the step-type copper busbar current detection device shown;

[0030] Fig.10 It is a schematic diagram of another step-type copper busbar current detection device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described through implementation methods with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the basic concepts disclosed and suggested by the embodiments of the present invention, all other embodiments obtained by those skilled in the art are within the scope of protection of the present invention.

[0032] refer to Figure 1, which is a schematic diagram of a step-type copper busbar current detection device provided by an embodiment of the present invention. The step copper busbar current detection device provided in this embodiment includes: a circuit board 3, a magnetic induction module 2 fixed on the circuit board 3, the magnetic induction module 2 at least including a first magnetic induction unit 211 and a second magnetic induction unit 212, the first magnetic induction unit 211 and the second magnetic induction unit 212 are located on the same horizontal plane, and the horizontal plane is parallel to the plane where the circuit board 3 is located; a step copper busbar 1, the side of the step copper busbar 1 facing the magnetic induction module 2 is stepped, the step copper busbar 1 at least includes a first step 11 and a second step 12 different from the first step 11, in a direction perpendicular to the circuit board 3, the first magnetic induction unit 211 is located above the first step 11, and the second magnetic induction unit 212 is located above the second step 12, and the step copper busbar 1 is electrically isolated from the magnetic induction module 2; the current to be measured flows through the cross section perpendicular to the step copper busbar 1, the first magnetic induction unit 211 and the second magnetic induction unit 212 differentially sense the differential mode magnetic field generated by the current to be measured flowing through the step copper busbar 1, and generate and output a differential voltage signal.

[0033] In this embodiment, the step-type copper busbar current detection device is provided with a step-type copper busbar and a magnetic induction module, so the step-type copper busbar current detection device is also a magnetic resistance current detection device. The specific working principle is that the magnetic induction module 2 differentially senses the differential mode magnetic field generated by the current to be measured flowing through the step-shaped part of the step-type copper busbar 1.

[0034] The optional step-type copper busbar current detection device further includes: a mechanical support housing 4, which wraps and fixes the magnetic induction module 2 and the step-type copper busbar 1. The mechanical support housing 4 not only wraps and fixes the various parts of the step-type copper busbar current detection device, but also provides an external interface.

[0035] The step-type copper busbar current detection device includes a circuit board 3. It can be understood that the plane where the circuit board 3 is located is perpendicular to the Z direction. In the direction Z perpendicular to the plane where the circuit board 3 is located, the optional magnetic induction module 2, the circuit board 3 and the step-type copper busbar 1 are arranged in sequence, that is, the magnetic induction module 2 and the step-type copper busbar 1 are located on opposite sides of the circuit board 3. Optionally, along the Z direction, the magnetic induction module 2 is fixedly arranged above the circuit board 3, and the step-type copper busbar 1 is arranged below the circuit board 3. The step-type copper busbar 1 is electrically isolated from the magnetic induction module 2, and the step-type copper busbar 1 is also electrically isolated from the circuit board 3.

[0036] The side of the stepped copper busbar 1 facing the magnetic induction module 2 is stepped. The cross section of the stepped copper busbar 1 is a cross section obtained by cutting with the XZ plane as the cutting plane, so the cross section of the stepped copper busbar 1 is parallel to the XZ plane. Figure 1The cross section of the magnetic induction module 2, the circuit board 3 and the stepped copper busbar 1 is shown. The side of the stepped copper busbar 1 facing the magnetic induction module 2 is stepped, and includes at least a first step 11 and a second step 12 different from the first step 11.

[0037] The magnetic induction module 2 at least includes a first magnetic induction unit 211 and a second magnetic induction unit 212, which are located on the same horizontal plane, and the horizontal plane is parallel to the plane where the circuit board 3 is located. In the direction Z perpendicular to the circuit board 3, the first magnetic induction unit 211 is located above the first step 11, and the second magnetic induction unit 212 is located above the second step 12.

[0038] The sensitivity direction of each magnetic induction unit in the optional magnetic induction module 2 is the same, and the sensitivity direction of the magnetic induction unit is the same as or opposite to the direction of the magnetic field generated by the stepped copper busbar 1 at the position of the magnetic induction unit. In this embodiment, the sensitivity direction of the first magnetic induction unit 211 and the second magnetic induction unit 212 is the same, and its sensitivity direction can be selected to be the rightward X direction as shown in the figure. The direction of the magnetic field generated by the stepped copper busbar 1 at the position of the first magnetic induction unit 211 and the second magnetic induction unit 212 is the same as the sensitivity direction of the magnetic induction unit, and the direction of the magnetic field generated by the stepped copper busbar 1 at the position of the first magnetic induction unit 211 and the second magnetic induction unit 212 is also the rightward X direction as shown in the figure. It can be understood that the sensitivity direction of the magnetic induction unit shown to the right is only an example, and relevant practitioners can reasonably design the sensitivity direction of the magnetic induction unit according to product requirements, which is not limited to the rightward direction as shown in the figure.

[0039] The current to be measured flows through the stepped copper busbar 1 in a current direction perpendicular to the cross section of the stepped copper busbar 1. Specifically, the current direction is perpendicular to the XZ plane and is perpendicular to the paper plane and inward. The first magnetic induction unit 211 and the second magnetic induction unit 212 sense the differential mode magnetic field generated by the current to be measured flowing through the stepped copper busbar 1 in a differential manner, and generate a differential voltage signal and output it.

[0040] The specific analysis process is as follows. Figure 2 As shown, Figure 1 The magnetic field simulation diagram of the step-type copper busbar current detection device is shown in FIG. The current I1 of the step-type copper busbar 1 is 50A, the cross-section width of the step-type copper busbar 1 along the Z direction is 10mm, and the magnetic induction module 2 is located at a horizontal position 0.6mm above the step-type copper busbar 1. When the current to be measured flows through the step-type copper busbar 1 in a current direction perpendicular to the XZ plane, a magnetic field is generated at the position of the magnetic induction module 2. The simulation diagram is shown in FIG. Figure 2 As shown, it can be seen that near the step rising section, the magnetic field in the same plane above the first step 11 and the second step 12 has an obvious difference, and the magnetic field distribution is relatively uniform.

[0041] Assume that the first magnetic induction unit 211 is located in the uniform magnetic field area above the first step 11, and the second magnetic induction unit 212 is located in the uniform magnetic field area above the second step 12. Since the material of the step-type copper busbar 1 is considered to be uniform, when the current to be measured flows through the step-type copper busbar 1 in a current direction perpendicular to the XZ plane, the current density in the step cross section can be regarded as the same, that is, the current magnitude is proportional to the cross-sectional area, so the step-type copper busbar 1 can be re-divided into two upper and lower rectangular cross-sectional parts according to the first step 11 and the second step 12. The height of the lower rectangle divided in the step-type copper busbar 1 is consistent with the height of the second step 12, and the width of the lower rectangle is the sum of the width of the first step 11 and the width of the second step 12; the height of the upper rectangle is the difference between the height of the first step 11 and the height of the second step 12, and the width of the upper rectangle is consistent with the width of the first step 11. Here, the height is the dimension along the Z direction, and the width is the dimension along the X direction.

[0042] Based on this, it can be considered that the first magnetic induction unit 211 and the second magnetic induction unit 212 are both located in the lower rectangular uniform magnetic field area, and the first magnetic induction unit 211 is also located in the upper rectangular uniform magnetic field area.

[0043] Let the current to be measured be I in , the current flowing through the stepped copper busbar 1 is I1, then the current I1 flowing through the stepped copper busbar 1 can be divided into the current I'1 flowing through the lower rectangle and the current ΔI1 flowing through the upper rectangle, and the formula (1) is obtained:

[0044] I1=I′1+ΔI1 (1).

[0045] Taking the rightward X direction as the positive direction of the magnetic field, according to the Bissard law of the magnetic field generated by the current-carrying wire, the magnetic field H generated by the current I1 of the stepped copper busbar 1 at the position of the first magnetic induction unit 211 is 211 The magnetic field H generated by the current I1 at the position of the second magnetic induction unit 212 changes linearly with the current. 212 With the current changing linearly, we get formula (2):

[0046] H 211 =k1I'1+k 21 ΔI1;

[0047] H 212 =k1I'1+k 22 ΔI1 (2).

[0048] Wherein, k1 is the linear constant of the uniform magnetic field generated by the lower rectangular current I'1 at the first magnetic induction unit 211 and the second magnetic induction unit 212, k 21 is the linear constant of the magnetic field generated by the rectangular current ΔI1 at the position of the first magnetic induction unit 211, k 22is the linear constant of the magnetic field generated by the upper rectangular current ΔI1 at the position of the second magnetic induction unit 212 .

[0049] Equivalent transformation is performed on equation (2), and the magnetic field at the positions of the first magnetic induction unit 211 and the second magnetic induction unit 212 is decomposed into the common mode magnetic field H CM and differential mode magnetic field H DM , we get formula (3):

[0050]

[0051] Accordingly, the magnetic field at the position of the first magnetic induction unit 211 and the magnetic field at the position of the second magnetic induction unit 212 can be converted into a common mode magnetic field H CM and differential mode magnetic field H DM Superposition expression, we get formula (4):

[0052] H 211 =H CM +H DM ;

[0053] H 212 =H CM -H DM (4).

[0054] As described above, the step-type copper busbar current detection device provided in this embodiment, I in =I1, combining equations (3) and (4), it can be seen that the magnetic field at the position of the first magnetic induction unit 211 and the second magnetic induction unit 212 is related to the current to be measured I in Proportional to the differential mode magnetic field H DM Realize the current detection to be measured.

[0055] The step-type copper busbar current detection device provided by the embodiment of the present invention has a first step and a second step with a height difference, and the magnetic induction unit in the magnetic induction module senses the differential mode magnetic field generated by the height difference between the first step and the second step in a differential manner; since the cross-sectional current density of the step-type copper busbar is the same, by adjusting the height of the first step and the second step, most of the current to be measured can flow through the lower rectangle of the step-type copper busbar away from the magnetic induction module and form a common mode magnetic field, so by adjusting and controlling the size of the differential mode magnetic field, the measurement current range can be expanded. The step-type copper busbar current detection device has the characteristics of adjustable common mode magnetic field working point, applicable to a variety of magnetic induction units, adjustable sensitivity, input and output electrical isolation, strong anti-common mode interference capability, and can measure AC and DC currents and large currents.

[0056] The magnetic induction unit in the optional magnetic induction module is composed of any one of the magnetoresistance sensitive elements of anisotropic magnetoresistance AMR, giant magnetoresistance GMR, tunnel magnetoresistance TMR and colossal magnetoresistance CMR.

[0057] The first magnetic induction unit optionally includes at least one magnetoresistive bridge arm, and the second magnetic induction unit includes at least one magnetoresistive bridge arm; the magnetoresistive bridge arm of the first magnetic induction unit and the magnetoresistive bridge arm of the second magnetic induction unit are electrically connected to form a differential half-bridge structure output or a differential full-bridge structure output, wherein the sensitivity direction of each magnetoresistive bridge arm is the same and is composed of at least one magnetoresistive sensitive element connected in series and parallel; the first magnetic induction unit and the second magnetic induction unit are located on the same chip or on two separate chips.

[0058] refer to Figure 3 As shown, Figure 1 The bridge structure schematic diagram of the step-type copper busbar current detection device is shown in FIG. The bridge structure of the step-type copper busbar current detection device is a differential full-bridge structure. Figure 3 As shown, the optional first magnetic induction unit 211 includes two magnetoresistive bridge arms 211a and 211b, and the second magnetic induction unit 212 includes two magnetoresistive bridge arms 212a and 212b; the four magnetoresistive bridge arms 211a, 211b, 212a and 212b are electrically connected to form a differential full-bridge structure. Among them, the sensitivity directions of the four magnetoresistive bridge arms 211a, 211b, 212a and 212b are the same, all horizontally to the right in the X direction. Each magnetoresistive bridge arm is composed of at least one magnetoresistive sensitive element connected in series and parallel. The magnetoresistive sensitive element of the optional magnetoresistive bridge arm adopts a tunnel magnetoresistor TMR; the optional first magnetic induction unit 211 and the second magnetic induction unit 212 are located on the same chip.

[0059] Combining the above analysis and Figure 3 It can be seen from the differential full-bridge structure shown that there is a difference between the magnetic field generated by the step copper busbar 1 at the first magnetic induction unit 211 and the magnetic field generated by the step copper busbar 1 at the second magnetic induction unit 212. Specifically, the rightward magnetic field generated by the step copper busbar 1 at the first magnetic induction unit 211 is greater than the rightward magnetic field generated by the step copper busbar 1 at the second magnetic induction unit 212. Since the sensitivity directions of the four magnetic resistance bridge arms 211a, 211b, 212a and 212b are all rightward, the rightward magnetic field at the positions of the magnetic resistance bridge arms 211a and 211b is greater than the rightward magnetic field at the positions of the magnetic resistance bridge arms 212a and 212b. Therefore, the resistance of the magnetic resistance bridge arms 211a and 211b is less than the resistance of the magnetic resistance bridge arms 212a and 212b, so it can be obtained that the V2 voltage is greater than the V1 voltage, forming a differential voltage signal.

[0060] The optional magnetic induction module 2 also includes a closed-loop signal conditioning circuit and a magnetic field feedback coil 22. The closed-loop signal conditioning circuit, the magnetic field feedback coil 22, the first magnetic induction unit 211 and the second magnetic induction unit 212 constitute a closed-loop magnetic field feedback component; after the differential voltage signal is amplified by the closed-loop signal conditioning circuit, a feedback magnetic field is generated through the magnetic field feedback coil 22 to reversely offset the differential mode magnetic field; when the magnetic field is dynamically balanced, the first magnetic induction unit 211 and the second magnetic induction unit 212 work at the same common mode magnetic field working point, and then the feedback current of the magnetic field feedback coil 22 is sampled through the sampling resistor to form the output signal of the magnetic induction module 2. Alternatively, in other embodiments, the optional magnetic induction module also includes an open-loop signal conditioning circuit, which performs conditioning, amplification, temperature compensation and linearity correction on the differential voltage signal.

[0061] In this embodiment, the optional magnetic field feedback coil 22 and the closed-loop signal conditioning circuit are integrated inside the magnetic induction unit. For example, the first magnetic induction unit 211 has a magnetic field feedback coil 22 and a closed-loop signal conditioning circuit integrated inside, and the second magnetic induction unit 212 has a magnetic field feedback coil 22 and a closed-loop signal conditioning circuit integrated inside. The optional closed-loop signal conditioning circuit is made of an ASIC application-specific integrated circuit.

[0062] The closed-loop signal conditioning circuit is used to condition, amplify, temperature compensate and linearize the differential voltage signal generated between the first magnetic induction unit 211 and the second magnetic induction unit 212. After the differential voltage signal is amplified by the closed-loop signal conditioning circuit, the feedback magnetic field is generated by the magnetic field feedback coil 22 to reversely offset the differential mode magnetic field. When the dynamic balance of the magnetic field is reached, the first magnetic induction unit 211 and the second magnetic induction unit 212 operate at equal common mode magnetic field operating points. Finally, the feedback current of the magnetic field feedback coil 22 is sampled by the sampling resistor to form the output of the magnetic induction module 2. At this time, the output signal of the magnetic induction module 2 is formed as the output signal of the step-type copper busbar current detection device.

[0063] The step-type copper busbar current detection device provided in this embodiment has a full-bridge circuit structure for the first magnetic induction unit and the second magnetic induction unit in the magnetic induction module and is located on the same chip, which can enhance the anti-interference ability and consistency; the step shape of the step-type copper busbar can enable the magnetic induction module to form a differential mode magnetic field; the magnetic field feedback coil is integrated inside the magnetic induction unit. Based on this, the step-type copper busbar current detection device has the characteristics of simple structure, small size, input and output electrical isolation, strong anti-common mode interference ability, and can measure AC and DC currents and large currents.

[0064] In other embodiments, the bridge structure of the step-type copper busbar current detection device can be selected as a differential half-bridge structure, wherein the first magnetic induction unit includes a magnetoresistive bridge arm, and the second magnetic induction unit includes a magnetoresistive bridge arm; the two magnetoresistive bridge arms are electrically connected to form a differential half-bridge structure output, wherein the sensitivity direction of each magnetoresistive bridge arm is the same and is composed of at least one magnetoresistive sensitive element connected in series and parallel; the first magnetic induction unit and the second magnetic induction unit are located on the same chip or on two separate chips. The optional magnetic induction module also includes an open-loop signal conditioning circuit, which conditions, amplifies, temperature compensates, and performs linearity correction on the differential voltage signal. Its working principle is similar to Figure 3 Similar, no further elaboration is required here.

[0065] It should be noted that only using the stepped copper busbar 1 to form a magnetic field can expand the measurement current range to a certain extent, but the expansion degree is still limited. Specifically, the common mode magnetic field H can be separated through the cross section of the stepped copper busbar 1. CM , thereby expanding the measurement current range, that is, the common mode magnetic field H CM The first magnetic induction unit 211 and the second magnetic induction unit 212 have the same effect, and theoretically have no effect on the output of the magnetic induction module 2. However, due to the characteristics of the magnetoresistive sensitive element itself, there will still be certain linearity consistency and saturation problems.

[0066] refer to Figure 4 As shown in FIG. 1 , a voltage-magnetic field curve diagram of a magnetoresistance sensitive element is shown. The magnetoresistance sensitive element in the optional magnetic induction module 2 is a tunnel magnetoresistance TMR. Figure 4 As shown in Figure 2, there is a certain range of linear intervals on both sides of the magnetic field zero point, and when it tends to saturation, the sensitivity of the tunnel magnetoresistance TMR will change, which is reflected in Figure 4 In the figure, the slope of the curve changes. Specifically, point A is in the linear range, point B is in the positive saturation range, and point C is in the negative saturation range.

[0067] According to the above formula (4), it can be assumed that the common mode magnetic field H in the three cases is CM The working points are A, B, C, H 211 The working points are A1, B1, C1, H 212 The working points are A2, B2, C2, H 211 With H CM The difference is H DM , H 212 With H CM The difference is H DM .

[0068] At point A in the linear interval, the sensitivities of the first magnetic induction unit 211 and the second magnetic induction unit 212 are consistent; while at points B and C in the saturation interval, there will be errors in the sensitivities of the first magnetic induction unit 211 and the second magnetic induction unit 212, that is, the slopes at B1 and B2 are quite different, and the slopes at C1 and C2 are quite different, which will affect the measurement accuracy of the current detection device.

[0069] Similarly, for input currents of different magnitudes, the common-mode magnetic field generated is different, which makes the sensitivity of the stepped copper busbar current detection device in the full range also have certain differences, so there will be certain problems with linear consistency. The above reasons limit the further expansion of the measurement current range.

[0070] Based on this, an embodiment of the present invention further provides another step-type copper busbar current detection device, which is different from any of the above embodiments in that a shunt copper busbar is introduced into the step-type copper busbar current detection device provided in this embodiment and the following embodiments. The role of the shunt copper busbar in the step-type copper busbar current detection device is, on the one hand, to further shunt the current to be measured and expand the measurement current range, and on the other hand, it can achieve the reduction and offset of the common mode magnetic field, so that the working point of the magnetic induction module returns from the saturation range to the linear range, so that the measurement current range can be significantly expanded while considering the linearity consistency.

[0071] refer to Figure 5 FIG. 1 is a schematic diagram of another step-type copper busbar current detection device provided by an embodiment of the present invention. Figure 5As shown, the step-type copper busbar current detection device provided in this embodiment includes: a step-type copper busbar 1, a shunt copper busbar 5, a magnetic induction module 2 and a circuit board 3, wherein the magnetic induction module 2 is fixed on the circuit board 3; the step-type copper busbar 1 and the shunt copper busbar 5 are connected in series and parallel to form a current input module to be measured, the magnetic induction module 2 and the circuit board 5 form a signal output module, and the current input module to be measured is electrically isolated from the signal output module; the side of the step-type copper busbar 1 facing the magnetic induction module 2 is step-shaped, and the step-type copper busbar 1 includes at least a first step 11 and a second step 12; the magnetic induction module 2 includes at least a first magnetic induction unit 211 and a second magnetic induction unit 212, and the first magnetic induction unit The first magnetic induction unit 211 and the second magnetic induction unit 212 are located on the same horizontal plane, and the horizontal plane is parallel to the plane where the circuit board 3 is located. In the direction Z perpendicular to the circuit board 3, the first magnetic induction unit 211 is located above the first step 11, and the second magnetic induction unit 212 is located above the second step 12; the current to be measured flows through the cross section perpendicular to the step-type copper bus 1 and the shunt copper bus 5, and generates a magnetic field at the position of the magnetic induction module 2; the first magnetic induction unit 211 and the second magnetic induction unit 212 differentially sense the magnetic field generated by the current to be measured flowing through the current to be measured input module, and generate a voltage signal, which forms the output signal of the step-type copper bus current detection device.

[0072] In this embodiment, a shunt copper busbar 5 is introduced, wherein the step copper busbar 1 and the shunt copper busbar 5 are located at the upper and lower sides of the magnetic induction module 2. The magnetic induction module 2 is fixed on the circuit board 3, and the plane where the circuit board 3 is located can be perpendicular to the Z direction. Along the Z direction, the step copper busbar 1 and the shunt copper busbar 5 are located at the upper and lower sides of the circuit board 3, and the step copper busbar 1 can be located below the circuit board 3, and the shunt copper busbar 5 is located above the circuit board 3, and the magnetic induction module 2 is fixed above the circuit board 3.

[0073] The step copper bar 1 and the shunt copper bar 5 are connected in series and parallel to form a current input module to be measured, and the magnetic induction module 2 and the circuit board 5 constitute a signal output module, and the current input module to be measured is electrically isolated from the signal output module. The plane where the circuit board 3 is located is perpendicular to the Z direction, so the cross section of the circuit board 3 is parallel to the XZ plane, and accordingly, the cross sections of the step copper bar 1 and the shunt copper bar 5 are parallel to the XZ plane. The current to be measured flows through the cross section perpendicular to the step copper bar 1 and the shunt copper bar 5. The shunt copper bar 5 can be connected in parallel with the step copper bar 1 to realize the common shunting of the current to be measured, so that the current direction of the current to be measured flowing through the step copper bar 1 and the shunt copper bar 5 is the same, both of which are perpendicular to the paper surface and inward.

[0074] Optionally, in the direction Z perpendicular to the circuit board 3, the vertical projection of the shunt copper busbar 5 on the circuit board 3 covers the vertical projection of each magnetic induction unit in the magnetic induction module 2 on the circuit board 3; the sensitivity direction of each magnetic induction unit is the same, and the sensitivity direction of the magnetic induction unit is the same as or opposite to the direction of the magnetic field generated by the step-type copper busbar 1 at the position of the magnetic induction unit, and the sensitivity direction of the magnetic induction unit is along the plane of the magnetic induction module 2 and perpendicular to the step rising cross-section direction of the step-type copper busbar 1. Among them, the shunt copper busbar 5 is located above the first magnetic induction unit 211 and the second magnetic induction unit 212, and the first magnetic induction unit 211 and the second magnetic induction unit 212 are both located in the magnetic field uniformity area within the coverage range of the vertical projection of the shunt copper busbar 5 along the Z direction. Specifically, the first magnetic induction unit 211 is located in the magnetic field uniformity area above the first step 11, and the second magnetic induction unit 212 is located in the magnetic field uniformity area above the second step 12.

[0075] Optionally, the first magnetic induction unit 211 and the second magnetic induction unit 212 are located on the same circuit board 3 ; or, the first magnetic induction unit 211 and the second magnetic induction unit 212 are located on two separate circuit boards 3 .

[0076] The magnetic induction unit in the optional magnetic induction module 2 is composed of any one of the magnetoresistance sensitive elements of anisotropic magnetoresistance AMR, giant magnetoresistance GMR, tunnel magnetoresistance TMR and giant magnetoresistance CMR. Alternatively, the magnetic induction unit in the optional magnetic induction module 2 is composed of any one of the magnetic induction elements of fluxgate, giant magnetoresistance GMI and magnetoelectric coupling device ME.

[0077] The number of shunt copper bars can be one or more; along the vertical direction Z of the circuit board 3, the position of any shunt copper bar is above the magnetic induction module 2 or below the step copper bar 1, and the vertical projection of the shunt copper bar on the plane where the circuit board 3 is located covers each magnetic induction unit in the magnetic induction module 2. The current direction of the shunt copper bar can be the same as or opposite to the current direction of the step copper bar 1 at the position of the magnetic induction module 2; in the step copper bar current detection device, the input range of the current to be measured of the step copper bar current detection device is adjusted by setting the series-parallel connection mode of the shunt copper bar and the step copper bar 1, and / or the input range of the current to be measured of the step copper bar current detection device is adjusted by setting the number of shunt copper bars.

[0078] like Figure 5The step-type copper busbar current detection device shown introduces a shunt copper busbar 5, and the position of the shunt copper busbar 1 is above the magnetic induction module 2; at the position of the magnetic induction module 2, the current direction of the shunt copper busbar 5 is the same as the current direction of the step-type copper busbar 1; the shunt copper busbar 5 shunts the current to be measured, and by setting the series-parallel connection mode of the shunt copper busbar 5 and the step-type copper busbar 1, the input range of the current to be measured of the step-type copper busbar current detection device can be adjusted, thereby further expanding the measurement current range.

[0079] The current to be measured flows through the step copper bus 1 and the shunt copper bus 5 in a current direction perpendicular to the cross-section of the step copper bus 1 and the shunt copper bus 5, and generates a magnetic field at the position of the magnetic induction module 2; the first magnetic induction unit 211 and the second magnetic induction unit 212 differentially sense the magnetic field generated by the current to be measured flowing through the current input module to be measured, and generate a voltage signal, which forms the output signal of the step copper bus current detection device. Among them, the shunt copper bus 5 generates a left common mode magnetic field at the position of the magnetic induction unit.

[0080] The specific analysis process is as follows. Figure 6 As shown, Figure 5 The magnetic field simulation diagram of the stepped copper busbar current detection device is shown. Figure 6 and Figure 2 By comparison, it can be seen that the similarities are that near the step rising section, the magnetic field in the same plane above the first step 11 and the second step 12 has a significant difference, and the magnetic field distribution is relatively uniform; the difference is that Figure 6 The magnetic field curve shown has a significant downward shift, that is, the leftward common mode magnetic field generated by the shunt copper bar 5 at the position of the magnetic induction unit and the rightward common mode magnetic field generated by the step copper bar 1 have offset and reduced each other. Obviously, by adjusting the thickness and relative position of the shunt copper bar 5, the offset common mode magnetic field may be in the same direction, zero or opposite direction.

[0081] The following Figure 6 The curve shown is used as an example for explanation. It can be understood that the common mode magnetic field after the shunt copper bus 5 and the stepped copper bus 1 are offset is in the same direction.

[0082] Let the current flowing through the shunt copper busbar 5 be I5, then we get formula (5):

[0083] I in =I1+I5=I'1+ΔI1+I5 (5).

[0084] Taking the rightward X direction as the positive direction of the magnetic field, assuming that the first magnetic induction unit 211 and the second magnetic induction unit 212 are located in the magnetic field uniform area of ​​the shunt copper bus 5, according to the Bissard law of the magnetic field generated by the current-carrying wire, equation (6) is obtained:

[0085] H 211 =k1I'1+k21 ΔI1-k3I5;

[0086] H 212 =k1I'1+k 22 ΔI1-k3I5 (6).

[0087] Wherein, k3 is a linear constant of the current I5 of the shunt copper bus 5 to generate a uniform magnetic field at the positions of the first magnetic induction unit 211 and the second magnetic induction unit 212 .

[0088] By performing an equivalent transformation on equation (6), we obtain equation (7):

[0089]

[0090] Then we can also get formula (4):

[0091] H 211 =H CM +H DM ;

[0092] H 212 =H CM -H DM (4).

[0093] It can be seen from equation (7) that the magnetic fields generated by I'1 and I5 at the first magnetic induction unit 211 and the second magnetic induction unit 212 are in opposite directions, cancel each other out and reduce each other, and only a common mode magnetic field H is generated. CM , no differential mode magnetic field H is generated DM , which mainly plays the role of adjusting and increasing the current input range of the step-type copper busbar current detection device. Similarly, combining equation (7) and equation (4), it can be seen that the magnetic field at the position of the first magnetic induction unit 211 and the second magnetic induction unit 212 is related to the current to be measured I in Proportional to the differential mode magnetic field H DM Realize the current detection to be measured.

[0094] The optional magnetic induction module also includes a closed-loop signal conditioning circuit and a magnetic field feedback coil; the closed-loop signal conditioning circuit conditions, amplifies, temperature compensates and corrects the linearity of the differential voltage signal; the closed-loop signal conditioning circuit, the magnetic field feedback coil, the first magnetic induction unit and the second magnetic induction unit constitute a closed-loop magnetic field feedback, and the differential voltage signal is amplified by the closed-loop signal conditioning circuit, and then a feedback magnetic field is generated through the magnetic field feedback coil to reversely offset the differential mode magnetic field; when the dynamic balance of the magnetic field is reached, the first magnetic induction unit and the second magnetic induction unit operate at equal common mode magnetic field operating points, and then the feedback current of the magnetic field feedback coil is sampled through the sampling resistor to form the output signal of the magnetic induction module.

[0095] The optional magnetic field feedback coil is integrated into a closed-loop signal conditioning circuit, a circuit board, each magnetic induction unit of the magnetic induction module, and an interior of one of the structures of the magnetic induction module.

[0096] like Figure 5 As shown, the closed-loop signal conditioning circuit, the magnetic field feedback coil 22, the first magnetic induction unit 211 and the second magnetic induction unit 212 constitute a closed-loop magnetic field negative feedback. For the closed-loop magnetic field negative feedback, as required, the magnetic field feedback coil 22 can be integrated into the closed-loop signal conditioning circuit, or as shown in FIG. Figure 5 As shown, it is integrated into the circuit board 3, or as shown Figure 1 As shown, the closed-loop magnetic field negative feedback components are integrated into the magnetic induction unit, or integrated into the ASIC dedicated integrated circuit, or integrated into the magnetic induction module 2. The working principles of the closed-loop magnetic field negative feedback components in the above different positions are roughly the same.

[0097] Here with Figure 5 Taking the example of the magnetic field feedback coil 22 integrated in the circuit board 3, the working principle of the closed-loop magnetic field negative feedback component is described. The plane where the magnetic field feedback coil 22 is located is parallel to the plane where the first magnetic induction unit 211 and the second magnetic induction unit 212 are located. The magnetic field feedback coil 22 is symmetrically distributed along the cross-section plane of the XZ plane on both sides of the midline, wherein the current direction on one side of the cross-section plane is perpendicular to the paper surface and outward, and the current direction on the other side of the cross-section plane is perpendicular to the paper surface and inward.

[0098] Regarding the direction of the feedback magnetic field generated by the magnetic field feedback coil 22, the magnetic field to the right at the first magnetic induction unit 211 is greater than the magnetic field to the right at the second magnetic induction unit 212. In order to reversely offset the differential mode magnetic field, Figure 5 In the cross-sectional view shown, the current direction of the wire section of the magnetic field feedback coil 22 arranged horizontally below the first magnetic induction unit 211 is perpendicular to the paper and outward, and the current direction of the wire section of the magnetic field feedback coil 22 arranged horizontally below the second magnetic induction unit 212 is perpendicular to the paper and inward. As a result, the magnetic field feedback coil 22 generates a leftward feedback magnetic field at the first magnetic induction unit 211, and the magnetic field feedback coil 22 generates a rightward feedback magnetic field at the second magnetic induction unit 212, thereby counteracting the differential mode magnetic field and achieving a dynamic balance of the magnetic field.

[0099] As for the case where the magnetic field feedback coil 22 is integrated at other positions, although the coil distribution or connection is slightly different, the magnetic field feedback principle is to use the distribution of the magnetic field feedback coil 22 to generate a magnetic field to offset the differential mode magnetic field, which will not be elaborated here.

[0100] refer to Figure 7 As shown, Figure 5 The bridge structure diagram of the step-type copper busbar current detection device is shown in FIG. Figure 7As shown, the optional first magnetic induction unit 211 is composed of a magnetoresistive bridge arm 211c, and the second magnetic induction unit 212 is composed of a magnetoresistive bridge arm 212c. The magnetoresistive bridge arm is composed of one or more magnetoresistive sensitive elements connected in series and parallel; the sensitivity directions of the two magnetoresistive bridge arms are the same and are electrically connected to form a differential half-bridge structure.

[0101] like Figure 7 As shown, the sensitivity directions of the two magnetoresistive bridge arms 211c and 212c are the same, both in the horizontal rightward X direction, and electrically form a differential half-bridge structure. The magnetoresistive sensitive elements constituting the magnetoresistive bridge arms 211c and 212c can optionally use anisotropic magnetoresistive AMR, and the first magnetic induction unit 211 and the second magnetic induction unit 212 can optionally be located on two separate chips.

[0102] According to the above analysis, the shunt copper bus 5 can only offset and reduce the common-mode magnetic field without generating a differential-mode magnetic field. Therefore, the common-mode magnetic field after offset may be in the same direction, return to zero, or be in the opposite direction.

[0103] Assuming that the common-mode magnetic field after cancellation is in the same direction, the differential-mode magnetic field causes the magnetic field to the right at the position of the first magnetic induction unit 211 to be greater than the magnetic field to the right at the position of the second magnetic induction unit 212. Since the sensitivity directions of the two magnetoresistive bridge arms 211c and 212c are both to the right, Figure 7 The magnetic field to the right at the middle magnetoresistance bridge arm 211c is greater than the magnetic field at the magnetoresistance bridge arm 212c, so the resistance of the magnetoresistance bridge arm 211c is less than the resistance of the magnetoresistance bridge arm 212c, realizing the change from magnetic field to voltage. Figure 7 Vout will change accordingly according to the current to be measured, forming a differential voltage signal.

[0104] The optional magnetic induction module 2 also includes a magnetic field feedback coil 22 integrated inside the circuit board and a closed-loop signal conditioning circuit using a PCB board-level discrete component circuit. Its function and principle are similar to Figure 1 The closed-loop magnetic field negative feedback is the same as that of the conventional magnetic field negative feedback, which will not be described in detail here. In this embodiment, the output of the magnetic induction module 2 forms the output signal of the step-type copper busbar current detection device.

[0105] In this embodiment, a step-type copper busbar and a shunt copper busbar are connected in parallel to shunt the current to be measured to form a current input module to be measured. The step-type copper busbar forms a differential mode magnetic field, and the common mode magnetic field formed by the shunt copper busbar offsets and reduces the common mode magnetic field of the step-type copper busbar, thereby expanding the measurement current range. The first magnetic induction unit and the second magnetic induction unit use a differential half-bridge circuit, and the magnetic field feedback coil is integrated inside the circuit board. The step-type copper busbar current detection device has the characteristics of adjustable common mode magnetic field working point, applicable to a variety of magnetic induction units, adjustable sensitivity, input and output electrical isolation, strong anti-common mode interference ability, and can measure AC and DC currents and large currents.

[0106] The optional step-type copper busbar current detection device includes more than one shunt copper busbar, so more than one shunt copper busbar is used for series-parallel connection to further adjust the common mode magnetic field. Along the vertical direction of the circuit board, the position of any shunt copper busbar is above the magnetic induction module or below the step-type copper busbar, and the vertical projection of the shunt copper busbar on the plane where the circuit board is located covers each magnetic induction unit in the magnetic induction module. Optionally, at the position of the magnetic induction module, the current direction of the shunt copper busbar is the same as or opposite to the current direction of the step-type copper busbar; in the step-type copper busbar current detection device, the input range of the current to be measured of the step-type copper busbar current detection device is adjusted by setting the series-parallel connection mode of the shunt copper busbar and the step-type copper busbar, and / or, the input range of the current to be measured of the step-type copper busbar current detection device is adjusted by setting the number of shunt copper busbars.

[0107] The following embodiments also provide a case where the step-type copper busbar current detection device includes two shunt copper busbars. It should be noted that the same contents as the above embodiment including one shunt copper busbar will not be described in detail.

[0108] refer to Figure 8 As shown in FIG. 1 , it is a schematic diagram of another step-type copper busbar current detection device provided by an embodiment of the present invention. Figure 8 As shown, the current detection device includes two shunt copper bars 51 and 52, wherein the shunt copper bar 51 is located above the magnetic induction module 2, and the shunt copper bar 52 is located below the stepped copper bar 1. The optional magnetic field feedback coil 22 is integrated inside the magnetic induction module 2.

[0109] From the above analysis, we know that Figure 5 By adjusting the thickness and relative position of the shunt copper bar 5, the common mode magnetic field after cancellation may be in the same direction, zeroed, or reversed, such as Figure 6 As shown, the common mode magnetic field after the shunt copper bus 5 and the stepped copper bus 1 are offset is in the same direction. Figure 8 The position of the first shunt copper bar 51 in Figure 5 The position of the middle shunt copper bus 5 is the same. In order to further reduce the common mode magnetic field to improve the linearity consistency and expand the measurement current range, the newly introduced second shunt copper bus 52 can be placed under the stepped copper bus 1, and the current direction in the second shunt copper bus 52 is perpendicular to the paper surface and outward, while the current direction of the stepped copper bus 1 and the shunt copper bus 51 is perpendicular to the paper surface and inward.

[0110] In other embodiments, the newly introduced second shunt copper busbar can be optionally placed above the first shunt copper busbar, and the current direction in the second shunt copper busbar is perpendicular to the paper surface and inward.

[0111] like Figure 8As shown, a shunt copper bar 52 is introduced below the step copper bar 1, and its current direction is perpendicular to the paper and outward, wherein the shunt copper bar 51 is connected in parallel with the step copper bar 1 and then connected in series with the shunt copper bar 52. At this time, the main function of the shunt copper bar 52 is to adjust the common mode magnetic field, and its internal current is the same as the current to be measured, and no shunt effect is generated.

[0112] refer to Fig. 9 As shown, Figure 8 The magnetic field simulation diagram of the stepped copper busbar current detection device is shown. Fig. 9 and Figure 6 The similarities are that near the step rising section, the magnetic field in the same plane above the first step 11 and the second step 12 has a significant difference, and the magnetic field distribution is relatively uniform; the difference is that Fig. 9 The magnetic field curve shown further moves downward and is closer to zero magnetic field, that is, the leftward common mode magnetic field generated by the shunt copper bar 52 at the magnetic induction unit position and the rightward common mode magnetic field after the offset are further offset and reduced.

[0113] Let the current flowing through the shunt copper bus 51 be I 51 , the current flowing through the shunt copper bus 52 is I 52 , then we get formula (8):

[0114] I in =I1+I 51 =I'1+ΔI1+I 51 ;

[0115] I in =I 52 (8).

[0116] Taking the rightward X direction as the positive direction of the magnetic field, assuming that the first magnetic induction unit 211 and the second magnetic induction unit 212 are located in the magnetic field uniform area of ​​the shunt copper bus 52, according to the Bissard law of the magnetic field generated by the current-carrying wire, equation (9) is obtained:

[0117] H 211 =k1I'1+k 21 ΔI1-k3I 51 -k4I 52 ;

[0118] H 212 =k1I'1+k 22 ΔI1-k3I 51 -k4I 52 (9).

[0119] Among them, k4 is the current I of the shunt copper bus 52 52 A linear constant of a uniform magnetic field is generated at the positions of the first magnetic induction unit 211 and the second magnetic induction unit 212 .

[0120] By performing an equivalent transformation on equation (9), we obtain equation (10):

[0121]

[0122] Then we can also get formula (4):

[0123] H 211 =H CM +H DM ;

[0124] H 212 =H CM -H DM (4).

[0125] From formula (10), we can see that I'1 and I 51 ,I 52 The magnetic fields generated at the first magnetic induction unit 211 and the second magnetic induction unit 212 are in opposite directions, cancel each other out and reduce each other, and only a common mode magnetic field H is generated. CM , no differential mode magnetic field H is generated DM , mainly plays the role of adjusting and increasing the current input range of the step-type copper busbar current detection device. Similarly, combining equation (10) and equation (4), it can be seen that the magnetic field at the position of the first magnetic induction unit 211 and the second magnetic induction unit 212 is related to the current to be measured I in Proportional to the differential mode magnetic field H DM Realize the current detection to be measured.

[0126] Figure 8 The magnetoresistance bridge arm in the step-type copper busbar current detection device shown in the figure can be adopted as follows Figure 7 In the differential half-bridge structure shown, the shunt copper bars 51 and 52 only offset and reduce the common-mode magnetic field, but do not generate a differential-mode magnetic field. Then the output signal Vout of the differential half-bridge structure will change accordingly according to the current to be measured, forming a differential voltage signal.

[0127] The optional magnetic induction module 2 further includes a magnetic field feedback coil 22 integrated inside the magnetic induction unit 2 and a closed-loop signal conditioning circuit using a PCB board-level discrete component circuit. The output of the magnetic induction module 2 forms an output signal of the stepped copper busbar current detection device.

[0128] In this embodiment, the first shunt copper bar is connected in parallel with the step copper bar, and then connected in series with the second shunt copper bar to form a current input module to be measured. The step copper bar forms a differential mode magnetic field, and the common mode magnetic field formed by the first shunt copper bar and the second shunt copper bar offsets and reduces the common mode magnetic field of the step copper bar, thereby expanding the measurement current range. The step copper bar current detection device has the characteristics of adjustable common mode magnetic field working point, applicable to a variety of magnetic induction units, adjustable sensitivity, input and output electrical isolation, strong anti-common mode interference ability, and can measure AC and DC currents and large currents.

[0129] The following embodiments also provide a case where the step-type copper busbar current detection device includes a shunt copper busbar. It should be noted that the same contents as the above embodiments including one or two shunt copper busbars are not described in detail. The step-type copper busbar current detection device may also include a shunt copper busbar, which may be placed under the step-type copper busbar, and the current direction in the shunt copper busbar is perpendicular to the paper and outward. Fig.10 As shown in FIG. 1 , it is a schematic diagram of another step-type copper busbar current detection device provided by an embodiment of the present invention. Fig.10 As shown, the current detection device includes a shunt copper bar 52, which is located below the step copper bar 1, and the shunt copper bar 52 is directly connected in series with the step copper bar 1, and the current direction of the step copper bar 1 is perpendicular to the paper surface and inward. The specific analysis process is as follows.

[0130] Let the current flowing through the shunt copper bus 52 be I 52 , then we get formula (11):

[0131] I in =I1=I 52 (11).

[0132] Taking the rightward X direction as the positive direction of the magnetic field, assuming that the first magnetic induction unit 211 and the second magnetic induction unit 212 are located in the magnetic field uniform area of ​​the shunt copper bus 52, according to the Bissard law of the magnetic field generated by the current-carrying wire, equation (12) is obtained:

[0133] H 211 =k1I'1+k 21 ΔI1-k4I 52 ;

[0134] H 212 =k1I'1+k 22 ΔI1-k4I 52 (12).

[0135] By performing an equivalent transformation on equation (12), we obtain equation (13):

[0136]

[0137] Then we can also get formula (4):

[0138] H 211 =H CM +H DM ;

[0139] H 212 =H CM -H DM (4).

[0140] It can be seen that I'1 and I 52 The magnetic fields generated at the first magnetic induction unit 211 and the second magnetic induction unit 212 are in opposite directions, cancel each other out and reduce each other, and only a common mode magnetic field H is generated. CM , no differential mode magnetic field H is generated DM , which mainly plays the role of adjusting and increasing the current input range of the step-type copper busbar current detection device. Similarly, combining equation (13) and equation (4), it can be seen that the magnetic field at the position of the first magnetic induction unit 211 and the second magnetic induction unit 212 is related to the current to be measured I in Proportional to the differential mode magnetic field H DM Realize the current detection to be measured.

[0141] The first magnetic induction unit 211 and the second magnetic induction unit 212 can be two giant magneto-impedance GMIs placed separately and with a sensitivity direction facing right. According to the above analysis, there is a difference in the magnetic field generated by the step-type copper bus 1 at the position of the first magnetic induction unit 211 and the position of the second magnetic induction unit 212, and the shunt copper bus 52 will only offset and reduce the common-mode magnetic field, but will not generate a differential-mode magnetic field. Therefore, there is a difference in the magnetic field sensed by the two separately placed giant magneto-impedance GMIs, which can generate a differential voltage signal.

[0142] The optional magnetic induction module 2 also includes an open-loop signal conditioning circuit, which performs conditioning amplification, temperature compensation, and linearity correction on the differential voltage signal. Specifically, the open-loop signal conditioning circuit uses a PCB board-level discrete component circuit, and the open-loop signal conditioning circuit performs conditioning amplification, temperature compensation, and linearity correction on the differential voltage signal of the first magnetic induction unit 211 and the second magnetic induction unit 212. The output of the magnetic induction module 2 forms the output signal of the step-type copper busbar current detection device.

[0143] In this embodiment, a shunt copper busbar is connected in series with the step copper busbar, and the current directions of the two are opposite. The step copper busbar forms a differential mode magnetic field, and the common mode magnetic field formed by the shunt copper busbar offsets and reduces the common mode magnetic field of the step copper busbar, thereby expanding the measurement current range. The current detection device of this embodiment has the characteristics of adjustable common mode magnetic field working point, applicable to a variety of magnetic induction units, adjustable sensitivity, simple structure, small size, input and output electrical isolation, and can measure AC and DC currents and large currents.

[0144] The above several embodiments of introducing shunt copper busbars are only typical cases. For example, in other embodiments, a current detection device of shunt copper busbars can be optionally introduced. The first magnetic induction unit is composed of two magnetoresistive bridge arms, and the second magnetic induction unit is composed of two magnetoresistive bridge arms. The magnetoresistive bridge arms are composed of one or more magnetoresistive sensitive elements connected in series and parallel. The sensitivity directions of the four magnetoresistive bridge arms are the same, and they are electrically connected to form a differential full-bridge structure. The first magnetic induction unit and the second magnetic induction unit are located on the same chip or on two separate chips. Obviously, there are many other embodiments of introducing shunt copper busbars, not limited to the above several typical embodiments.

[0145] It can be understood that there are many embodiments for introducing shunt copper bars, but after introducing one or more shunt copper bars and adopting a series-parallel connection mode, the analysis and calculation are roughly the same as the above analysis process. In addition, no matter which case is adopted, for the step-type copper bar current detection device introducing the shunt copper bar, the ideal condition in most applications is that the common mode magnetic field is completely offset. At this time, the measurement current range of the step-type copper bar current detection device can reach the maximum, that is, the differential mode magnetic field can be completely extended to the working range of the magnetoresistive sensitive element, then the following equations (14) and (15) can be obtained:

[0146]

[0147]

[0148] Furthermore, in an ideal situation, the magnetic field generated by the upper rectangular current ΔI1 at the position of the second magnetic induction unit 42 is very small, and it can be approximately considered that k 22 =0, then the above formula (14) can be simplified to the following formulas (16) and (17):

[0149]

[0150] H 211 =H DM =k 21 ΔI1 / 2,H 212 =-H DM =-k 21 ΔI1 / 2, (17).

[0151] The magnetic field at the positions of the first magnetic induction unit 211 and the second magnetic induction unit 212 is proportional to the current to be measured I in Proportional to the differential mode magnetic field H DM The current to be measured is detected. Combining equations (16) and (17), it can be seen that under ideal conditions, the common-mode magnetic field H CM is completely offset, and the working range of the magnetoresistive sensitive element can be determined by the differential mode magnetic field H DMFull coverage provides the maximum measurement current range.

[0152] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A step-type copper busbar current detection device, characterized in that: include: Circuit board, A magnetic induction module fixed on the circuit board, the magnetic induction module at least comprising a first magnetic induction unit and a second magnetic induction unit, the first magnetic induction unit and the second magnetic induction unit are located on the same horizontal plane, and the horizontal plane is parallel to the plane where the circuit board is located; A stepped copper busbar, wherein a side of the stepped copper busbar facing the magnetic induction module is stepped, the stepped copper busbar comprises at least a first step and a second step different from the first step, in a direction perpendicular to the circuit board, the first magnetic induction unit is located above the first step, and the second magnetic induction unit is located above the second step, and the stepped copper busbar is electrically isolated from the magnetic induction module; The current to be measured flows through a cross section perpendicular to the stepped copper busbar, and the first magnetic induction unit and the second magnetic induction unit sense the differential mode magnetic field generated by the current to be measured flowing through the stepped copper busbar in a differential manner, and generate and output a differential voltage signal; The stepped copper bus is electrically isolated from the circuit board.

2. The step-type copper busbar current detection device according to claim 1 is characterized in that: The sensitivity directions of the magnetic induction units in the magnetic induction module are the same, and the sensitivity directions of the magnetic induction units are the same as or opposite to the direction of the magnetic field generated by the stepped copper busbar at the position of the magnetic induction unit.

3. The step-type copper busbar current detection device according to claim 1, characterized in that: Also includes: A mechanical support shell wraps and fixedly supports the magnetic induction module and the stepped copper busbar.

4. The step-type copper busbar current detection device according to claim 1, characterized in that: The first magnetic induction unit includes at least one magnetoresistive bridge arm, and the second magnetic induction unit includes at least one magnetoresistive bridge arm; The magnetoresistance bridge arm of the first magnetic induction unit and the magnetoresistance bridge arm of the second magnetic induction unit are electrically connected to form a differential half-bridge structure output or a differential full-bridge structure output, wherein each of the magnetoresistance bridge arms has the same sensitivity direction and is composed of at least one magnetoresistance sensitive element connected in series and parallel; the first magnetic induction unit and the second magnetic induction unit are located on the same chip or on two separate chips.

5. The step-type copper busbar current detection device according to claim 1, characterized in that: The magnetic induction module further includes a closed-loop signal conditioning circuit and a magnetic field feedback coil. The closed-loop signal conditioning circuit, the magnetic field feedback coil, the first magnetic induction unit and the second magnetic induction unit constitute a closed-loop magnetic field feedback component. After the differential voltage signal is amplified by the closed-loop signal conditioning circuit, a feedback magnetic field is generated by the magnetic field feedback coil to reversely offset the differential mode magnetic field. When the magnetic field is dynamically balanced, the first magnetic induction unit and the second magnetic induction unit operate at an equal common mode magnetic field operating point, and then the feedback current of the magnetic field feedback coil is sampled by a sampling resistor to form an output signal of the magnetic induction module. or, The magnetic induction module also includes an open-loop signal conditioning circuit, which performs conditioning, amplification, temperature compensation and linearity correction on the differential voltage signal.

6. A step-type copper busbar current detection device, characterized in that: include: A stepped copper bus, a shunt copper bus, a magnetic induction module and a circuit board, wherein the magnetic induction module is fixed on the circuit board; The stepped copper busbar and the shunt copper busbar are connected in series and parallel to form a current input module to be measured, the magnetic induction module and the circuit board form a signal output module, and the current input module to be measured is electrically isolated from the signal output module; The side of the stepped copper busbar facing the magnetic induction module is stepped, and the stepped copper busbar comprises at least a first step and a second step; The magnetic induction module at least includes a first magnetic induction unit and a second magnetic induction unit, the first magnetic induction unit and the second magnetic induction unit are located on the same horizontal plane, and the horizontal plane is parallel to the plane where the circuit board is located, in a direction perpendicular to the circuit board, the first magnetic induction unit is located above the first step, and the second magnetic induction unit is located above the second step; The current to be measured flows through a cross section perpendicular to the stepped copper busbar and the shunt copper busbar, and generates a magnetic field at the position of the magnetic induction module; the first magnetic induction unit and the second magnetic induction unit sense the magnetic field generated by the current to be measured flowing through the current input module to be measured in a differential manner, and generate a voltage signal, which forms an output signal of the stepped copper busbar current detection device; the magnetic field includes a differential mode magnetic field and a common mode magnetic field; the voltage signal is a differential voltage signal; The stepped copper bus is electrically isolated from the circuit board.

7. The step-type copper busbar current detection device according to claim 6, characterized in that: In a direction perpendicular to the circuit board, the vertical projection of the shunt copper bar on the circuit board covers the vertical projection of each magnetic induction unit in the magnetic induction module on the circuit board; The sensitivity direction of each of the magnetic induction units is the same, and the sensitivity direction of the magnetic induction unit is the same as or opposite to the direction of the magnetic field generated by the stepped copper bus at the position of the magnetic induction unit. The sensitivity direction of the magnetic induction unit is along the plane of the magnetic induction module and perpendicular to the step rising cross-section direction of the stepped copper bus.

8. The step-type copper busbar current detection device according to claim 6, characterized in that: The first magnetic induction unit and the second magnetic induction unit are located on the same circuit board; or, The first magnetic induction unit and the second magnetic induction unit are located on two separate circuit boards.

9. The step-type copper busbar current detection device according to claim 6, characterized in that: The first magnetic induction unit is composed of a magnetoresistive bridge arm, and the second magnetic induction unit is composed of a magnetoresistive bridge arm, and the magnetoresistive bridge arm is composed of one or more magnetoresistive sensitive elements connected in series and parallel; the sensitivity directions of the two magnetoresistive bridge arms are the same, and they are electrically connected to form a differential half-bridge structure; or, The first magnetic induction unit is composed of two magnetoresistive bridge arms, the second magnetic induction unit is composed of two magnetoresistive bridge arms, and the magnetoresistive bridge arms are composed of one or more magnetoresistive sensitive elements connected in series and parallel; the sensitivity directions of the four magnetoresistive bridge arms are the same, and they are electrically connected to form a differential full-bridge structure; The first magnetic induction unit and the second magnetic induction unit are located on the same chip or on two separate chips.

10. The step-type copper busbar current detection device according to claim 6, characterized in that: The magnetic induction module further includes an open-loop signal conditioning circuit, which performs conditioning, amplification, temperature compensation and linearity correction on the differential voltage signal; or, The magnetic induction module also includes a closed-loop signal conditioning circuit and a magnetic field feedback coil; the closed-loop signal conditioning circuit conditions, amplifies, temperature compensates and corrects the linearity of the differential voltage signal; the closed-loop signal conditioning circuit, the magnetic field feedback coil, the first magnetic induction unit and the second magnetic induction unit constitute a closed-loop magnetic field feedback, and the differential voltage signal is amplified by the closed-loop signal conditioning circuit, and then the magnetic field feedback coil generates a feedback magnetic field to reversely offset the differential mode magnetic field; when the dynamic balance of the magnetic field is reached, the first magnetic induction unit and the second magnetic induction unit operate at an equal common mode magnetic field operating point, and then the feedback current of the magnetic field feedback coil is sampled by a sampling resistor to form the output signal of the magnetic induction module.

11. The step-type copper busbar current detection device according to any one of claims 6 to 10, characterized in that: The number of the shunt copper bars is one or more; Along the vertical direction of the circuit board, any one of the shunt copper bars is located above the magnetic induction module or below the stepped copper bar, and the vertical projection of the shunt copper bar on the plane where the circuit board is located covers each magnetic induction unit in the magnetic induction module.

12. The step-type copper busbar current detection device according to claim 11, characterized in that: At the position of the magnetic induction module, the current direction of the shunt copper busbar is the same as or opposite to the current direction of the stepped copper busbar; In the step-type copper busbar current detection device, the input range of the current to be measured of the step-type copper busbar current detection device is adjusted by setting the series-parallel connection mode of the shunt copper busbar and the step-type copper busbar, and / or the input range of the current to be measured of the step-type copper busbar current detection device is adjusted by setting the number of the shunt copper busbars.

Images