Current sensing device with stepped copper bars

Abstract

To provide a stepped copper bar current measuring device. [Solution] The device comprises a circuit board (3), a magnetic induction module (2), and a stepped copper bar (1), the magnetic induction module (2) comprises a first magnetic induction unit (211) and a second magnetic induction unit (212), the side of the stepped copper bar (1) facing the magnetic induction module (2) comprises a first step (11) and a second step (12) that are different from each other, 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), a current to be measured flows through a cross section perpendicular to the stepped copper bar (1), the first magnetic induction unit (211) and the second magnetic induction unit (212) differentially induce a differential mode magnetic field generated by the current flowing through the stepped copper bar (1), generate a differential voltage signal, and output the differential voltage signal. The device has the characteristics of having an adjustable common mode magnetic field operating point, being applicable to various magnetic induction units, having adjustable sensitivity, realizing electrical isolation between input and output, having strong resistance to common mode interference, being able to measure AC and DC currents, and having large currents.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to the technical field of electrical measurements, and in particular to a current sensing device with a stepped copper bar. [Background technology]

[0002] Current sensing devices are widely used in industrial automation, detection, power monitoring, inverter power supplies, electric vehicles, and other fields. Currently, commonly used current sensing devices include shunts based on copper bars to realize signal input, current transformers and Rogowski coils based on the principle of electromagnetic induction, fiber optic current sensors, and magnetic current sensors that use conductive materials to generate a magnetic field for input to a magnetic induction element.

[0003] Shunts are built on the principle that when a direct current passes through a resistor, a voltage is generated across the resistor. Essentially, a shunt is a resistor with a very low resistance that converts a current signal into a voltage signal by directly applying Ohm's law. There is an electrical connection between the current loop being measured and the shunt's measuring loop, and there is no electrical isolation between the signal output and the current loop being measured, so mutual interference occurs between the two. Shunts are suitable for low frequencies and low power; they cannot measure currents in high-voltage loops, and it is difficult to measure high 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. Open-type current transformers, on the other hand, have an air gap in their magnetic circuit, resulting in relatively large error and large size. Rogowski coils, similar to current transformers, have an air-core design. Rogowski coils can be attached directly to the conductor being measured and are suitable for measuring AC currents over a wide frequency range, but cannot measure DC currents. Rogowski coils also have low sensitivity and are large in size.

[0005] The functional optical fiber current sensor is based on the Faraday effect of magneto-optical crystals. The functional optical fiber sensor is sensitive to and can detect external information, using optical fiber as the sensing element. The functional optical fiber sensor has high measurement accuracy and is easy to miniaturize, but it requires the use of special optical fiber, which is costly.

[0006] Magnetic-current sensors use different structural designs of current-carrying conductor materials to generate a magnetic field in space, then use various magnetic induction elements to sense the magnetic field and output a voltage signal to detect current. Interference significantly affects the accuracy of current measurement. The current measurement accuracy of magnetic-current sensors can be improved by improving the sensor's interference resistance. A commonly adopted design for existing magnetic-current sensors to improve their interference resistance is to use the difference in magnetic fields generated by current-carrying conductors at different positions in space to perform differential testing of the magnetic field passing through the magnetic induction element.

[0007] Current measurement realized in differential mode includes the following: (1) A current detection method that uses two magnetic induction elements to differentially sense the magnetic field inside the same annular iron core. However, there are problems with magnetic leakage in the air gap of the iron core, and the magnetic ring structure is large in volume and weight. Because the magnetic field lines inside the annular iron core pass directly through the magnetic sensing unit, it is difficult to adjust the operating point and input signal range of the common-mode magnetic field, and the magnetic sensing unit easily saturates when measuring large currents. (2) A method that uses a U-shaped wire to generate differential signals in opposite directions, or a copper bar with a recess in the neck as the signal input, or a copper busbar wire under test with a rectangular or rounded rectangular cross section as the signal input. However, when the current under test is large, the magnetic field generated by the current passing through the wire is directly used as the input signal for the magnetoresistive sensing element for differential detection. Therefore, when measuring large currents, the common-mode magnetic field saturates the magnetoresistive sensor chip, resulting in a limited input range. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION Embodiments of the present invention provide a current sensing device with a stepped copper bar to solve the problem of limited measurement accuracy and range of existing current sensors. [Means for solving the problem]

[0009] One embodiment of the present invention is a current sensing device comprising a stepped copper bar, A circuit board; a magnetic induction module fixed on a circuit board, the magnetic induction module including at least a first magnetic sensing unit and a second magnetic sensing unit, the first magnetic sensing unit and the second magnetic sensing unit being located on the same horizontal plane, the horizontal plane being parallel to a plane on which the circuit board is located; a stepped copper bar, the side of the stepped copper bar facing the magnetic induction module being stepped, the stepped copper bar comprising at least a first step and a second step different from the first step, the first magnetic sensing unit being located above the first step and the second magnetic sensing unit being located above the second step in a direction perpendicular to the circuit board, the stepped copper bar being electrically insulated from the magnetic induction module; A current detection device is provided that includes a stepped copper bar, in which a current to be measured flows through a cross section perpendicular to the stepped copper bar, and a first magnetic sensing unit and a second magnetic sensing unit differentially sense a differential mode magnetic field generated by the current to be measured flowing through the stepped copper bar, and generate and output a differential voltage signal.

[0010] An embodiment of the present invention further provides a current detection device with a stepped copper bar, the current detection device comprising: a stepped copper bar, a current shunt copper bar, a magnetic induction module, and a circuit board, the magnetic induction module being fixed on the circuit board, the current detection device comprising: The stepped copper bar and the copper bar for the current shunt are connected in series and in parallel to form a measured current input module, the magnetic induction module and the circuit board form a signal output module, and the measured current input module is electrically isolated from the signal output module; The stepped copper bar has a stepped side facing the magnetic induction module, and the stepped copper bar has at least a first step and a second step; the magnetic induction module comprises at least a first magnetic sensing unit and a second magnetic sensing unit, the first magnetic sensing unit and the second magnetic sensing unit are located on the same horizontal plane, the horizontal plane is parallel to a surface on which the circuit board is located, and in a direction perpendicular to the circuit board, the first magnetic sensing unit is located above a first step, and the second magnetic sensing unit is located above a second step; A current detection device with a stepped copper bar is provided, in which a current to be measured flows through a cross section perpendicular to the stepped copper bar and the copper bar for the current shunt, generating a magnetic field at the position of the magnetic induction module, and a first magnetic sensing unit and a second magnetic sensing 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 that forms an output signal of the current detection device with the stepped copper bar.

[0011] In a current detection device with a stepped copper bar provided by an embodiment of the present invention, the stepped copper bar has a first step and a second step with a height difference, and the magnetic sensing unit of the magnetic induction module differentially senses the differential-mode magnetic field generated by the height difference between the first step and the second step. Because the cross-sectional current density of the stepped copper bar is the same, by adjusting the height of the first step and the second step, most of the current to be measured flows through the rectangular part below the stepped copper bar and away from the magnetic induction module, forming a common-mode magnetic field. At the same time, the size of the differential-mode magnetic field can be adjusted and controlled to expand the measurement current range. The current detection device with a stepped copper bar has characteristics such as an adjustable common-mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, input / output electrical isolation, strong common-mode interference resistance, the ability to measure DC and AC currents, and the ability to measure large currents.

[0012] In order to more clearly show the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings necessary for use in the embodiments or the prior art are briefly introduced below. Of course, the accompanying drawings described below are some specific embodiments of the present invention, but it is clear to those skilled in the art that the basic concepts of the device structure, driving method and manufacturing method disclosed and promoted by various embodiments of the present invention can be extended and expanded to other structures and drawings, which all fall within the scope of the claims of the present invention. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram illustrating a current sensing device with a stepped copper bar according to an embodiment of the present invention. [Figure 2] 2 is a magnetic field simulation diagram of the current detection device with the stepped copper bar shown in FIG. 1. FIG. [Figure 3] 2 is a schematic diagram showing a bridge structure of the current detection device with stepped copper bars shown in FIG. 1. [Figure 4] FIG. 1 is a schematic diagram showing voltage-magnetic field curves of a magnetoresistive sensing element current detection device. [Figure 5] FIG. 10 is a schematic diagram illustrating another current sensing device with a stepped copper bar according to an embodiment of the present invention. [Figure 6] FIG. 6 is a magnetic field simulation diagram of the current detection device with the stepped copper bar shown in FIG. 5. [Figure 7] FIG. 6 is a schematic diagram showing the bridge structure of the current detection device with the stepped copper bar shown in FIG. 5. [Figure 8] FIG. 10 is a schematic diagram illustrating yet another current sensing device with a stepped copper bar according to an embodiment of the present invention. [Figure 9] FIG. 9 is a magnetic field simulation diagram of the current detection device with the stepped copper bar shown in FIG. 8. [Figure 10] FIG. 10 is a schematic diagram illustrating yet another current sensing device with a stepped copper bar according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and fully described below through implementation examples in the embodiments of the present invention with reference to the accompanying drawings. Of course, the described embodiments are only a part of the embodiments of the present invention, and are not all. Based on the basic concepts disclosed and promoted by the embodiments of the present invention, all other embodiments obtained by those skilled in the art are within the protection scope of the present invention.

[0015] 1, which is a schematic diagram of a current detection device with a stepped copper bar according to one embodiment of the present invention. The current detection device with a stepped copper bar 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 including at least a first magnetic sensing unit 211 and a second magnetic sensing unit 212, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 being located on the same horizontal plane, the horizontal plane being parallel to the plane on which the circuit board 3 is located, and a stepped copper bar 1, the side of the stepped copper bar 1 facing the magnetic induction module 2 being stepped, and the first step 11 and the second step 12 being different from each other. and a stepped copper bar 1 having at least two steps 12, a first magnetic sensing unit 211 located above the first step 11 and a second magnetic sensing unit 212 located above the second step 12 in a direction perpendicular to the circuit board 3, and electrically insulated from the magnetic induction module 2, wherein a current to be measured flows through a cross section perpendicular to the stepped copper bar 1, and the first magnetic sensing unit 211 and the second magnetic sensing unit 212 differentially sense a differential mode magnetic field generated by the current to be measured flowing through the stepped copper bar 1, and generate and output a differential voltage signal.

[0016] In this embodiment, the current detection device with the stepped copper bar includes the stepped copper bar and a magnetic induction module, and therefore the current detection device with the stepped copper bar is also a magnetoresistive current detection device. The specific working principle is that the magnetic induction module 2 differentially senses the differential mode magnetic field generated by the measured current flowing through the stepped portion of the stepped copper bar 1.

[0017] Optionally, the current detection device with stepped copper bars also includes a mechanical support housing 4 that encases, secures, and supports the magnetic induction module 2 and the stepped copper bars 1. The mechanical support housing 4 not only encases, secures, and supports various parts of the current detection device with stepped copper bars, but also provides an external boundary surface.

[0018] The current detection device with a stepped copper bar includes a circuit board 3. The plane on which the circuit board 3 is located can be understood to be perpendicular to the Z direction. In the Z direction perpendicular to the plane on which the circuit board 3 is located, the magnetic induction module 2, the circuit board 3, and the stepped copper bar 1 are optionally arranged in this order, that is, the magnetic induction module 2 and the stepped copper bar 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 stepped copper bar 1 is arranged below the circuit board 3, with the stepped copper bar 1 being electrically insulated from the magnetic induction module 2 and also electrically insulated from the circuit board 3.

[0019] The side of the stepped copper bar 1 facing the magnetic induction module 2 is stepped, and the cross section of the stepped copper bar 1 is a cross section obtained by cutting the stepped copper bar 1 along the XZ plane, and therefore the cross section of the stepped copper bar 1 is parallel to the XZ plane. Figure 1 shows a cross section of the magnetic induction module 2, a circuit board 3, and the stepped copper bar 1. The side of the stepped copper bar 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.

[0020] The magnetic induction module 2 includes at least a first magnetic sensing unit 211 and a second magnetic sensing unit 212, which are located on the same horizontal plane, which is parallel to the surface on which the circuit board 3 is located. In a direction Z perpendicular to the circuit board 3, the first magnetic sensing unit 211 is located above the first step 11, and the second magnetic sensing unit 212 is located above the second step 12.

[0021] Optionally, the sensitivity directions of the magnetic sensing units of the magnetic induction module 2 are the same, and the sensitivity directions of the magnetic sensing units are the same or opposite to the direction of the magnetic field generated by the stepped copper bar 1 at the position of the magnetic sensing units. In this embodiment, the sensitivity directions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are the same, and their sensitivity directions are optionally the right-facing X direction as shown in the drawings. Because the direction of the magnetic field generated by the stepped copper bar 1 at the position of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 is the same as the sensitivity directions of the magnetic sensing units, the direction of the magnetic field generated by the stepped copper bar 1 at the position of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 is also the right-facing X direction as shown in the drawings. The right-facing sensitivity direction of the magnetic sensing units is merely an example, and it can be understood that practitioners in the relevant field can reasonably design the sensitivity directions of the magnetic sensing units according to product requirements and are not limited to the right-facing direction shown in the drawings.

[0022] The current to be measured flows through the stepped copper bar 1 in a current direction perpendicular to the cross section of the stepped copper bar 1. Specifically, the current direction is perpendicular to the XZ plane and perpendicular to the paper surface, pointing inward. The first magnetic sensing unit 211 and the second magnetic sensing unit 212 differentially sense the differential mode magnetic field generated by the current to be measured flowing through the stepped copper bar 1, and generate and output a differential voltage signal.

[0023] The specific analysis process is as follows: Figure 2 is a magnetic field simulation diagram of the current detection device with the stepped copper bar shown in Figure 1. The current of the stepped copper bar 1 I1The current is 50A, the cross-section of the stepped copper bar 1 along the Z direction is 10mm, and the magnetic induction module 2 is located 0.6mm above the stepped copper bar 1 in the horizontal plane. When the current to be measured flows through the stepped copper bar 1 in a direction perpendicular to the XZ plane, a magnetic field is generated at the position of the magnetic induction module 2. A simulation diagram is shown in Figure 2, which shows that near the step-up section, there is a clear difference between the magnetic fields in the same plane above the first step 11 and the second step 12, and the magnetic field distribution is relatively uniform.

[0024] Assume that the first magnetic sensing unit 211 is located in a uniform magnetic field region above the first step 11, and the second magnetic sensing unit 212 is located in a uniform magnetic field region above the second step 12. Since the material of the stepped copper bar 1 is considered to be uniform, when the current to be measured flows through the stepped copper bar 1 in a current direction perpendicular to the XY plane, the current density at the step cross section can be considered to be the same, that is, the magnitude of the current is proportional to the cross-sectional area. Therefore, the stepped copper bar 1 can be subdivided into two, i.e., upper and lower rectangular cross-sectional parts according to the first step 11 and second step 12. The height of the divided lower rectangle of the stepped copper bar 1 is consistent with the height of the second step 12, 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, and 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.

[0025] Based on this, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 can be considered to be both located within the lower rectangular uniform magnetic field region, and the first magnetic sensing unit 211 can also be considered to be located within the upper rectangular uniform magnetic field region.

[0026] Let the measured current be I inIf the current flowing through the stepped copper bar 1 is I1, the current I1 flowing through the stepped copper bar 1 can be divided into the current I'1 flowing through the lower rectangle and the current ΔI1 flowing through the upper rectangle, and equation (1) is obtained. I1=I'1+ΔI1(1)

[0027] According to the Biot-Savart law that a current-carrying wire generates a magnetic field, with the right-facing X direction being the positive direction of the magnetic field, the magnetic field H generated by the current I1 in the stepped copper bar 1 at the position of the first magnetic sensing unit 211 is 211 varies linearly with the current and is the magnetic field H generated by the current I1 at the location of the second magnetic sensing unit 212. 212 varies linearly with the current, yielding equation (2). H 211 =k1I'1+k 21 ΔI1; H 212 =k1I'1+k 22 ΔI1(2) where k1 is the linear constant of the uniform magnetic field generated by the current I'1 of the lower rectangular at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212, and k 21 is the linear constant of the magnetic field generated by the current ΔI1 of the upper rectangular at the position of the first magnetic sensing unit 211, k 22 is the linear constant of the magnetic field generated by the current ΔI1 of the upper rectangle at the position of the second magnetic sensing unit 212.

[0028] By performing an equivalent transformation on Equation (2), the magnetic fields at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are expressed as the common-mode magnetic field H CM and the differential mode magnetic field H DM and equation (3) is obtained.

[0029]

number

[0030] Correspondingly, the magnetic field at the position of the first magnetic sensing unit 211 and the magnetic field at the position of the second magnetic sensing unit 212 form a common-mode magnetic field H CM and the differential mode magnetic field H DM can be converted into a convolution equation, and equation (4) is obtained. H 211 =H CM +H DM ; H 212 =H CM -H DM (4)

[0031] As described above, in the current detection device with the stepped copper bar provided by this embodiment, I in Combining equations (3) and (4), the magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 is expressed as the measured current I in The measured current is proportional to the differential mode magnetic field H DM It can be seen that this can be detected by measuring

[0032] In a current detection device with a stepped copper bar provided by an embodiment of the present invention, the stepped copper bar has a first step and a second step having a height difference, and the magnetic sensing unit of the magnetic induction module differentially senses the differential-mode magnetic field generated by the height difference between the first step and the second step. Because the current density of the stepped copper bar is the same across its cross section, by adjusting the heights of the first and second steps, most of the current to be measured flows through the lower rectangle on the surface of the stepped copper bar and away from the magnetic induction module, forming a common-mode magnetic field. At the same time, the size of the differential-mode magnetic field can be adjusted and controlled so as to extend the measurement current range. The current detection device with a stepped copper bar has characteristics such as an adjustable common-mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, input / output electrical isolation, strong common-mode interference resistance, and the ability to measure large AC and DC currents.

[0033] Optionally, the magnetic sensing unit of the magnetic induction module is composed of a magnetoresistive sensing element selected from the group consisting of an anisotropic magnetoresistor AMR, a giant magnetoresistor GMR, a tunneling magnetoresistor TMR, and a colossal magnetoresistor CMR.

[0034] Optionally, the first magnetic sensing unit comprises at least one magnetoresistive bridge arm, the second magnetic sensing unit comprises at least one magnetoresistive bridge arm, the magnetoresistive bridge arms of the first magnetic sensing unit and the magnetoresistive bridge arms of the second magnetic sensing unit are electrically connected to form a differential half-bridge structure output or connected to form a differential full-bridge structure output, all the magnetoresistive bridge arms have the same sensitivity direction, the magnetoresistive bridge arms are formed by connecting at least one magnetoresistive sensing element in series and parallel, and the first magnetic sensing unit and the second magnetic sensing unit are located on the same chip or two separate chips.

[0035] FIG. 3 is a schematic diagram of the bridge structure of the current sensing device with stepped copper bars shown in FIG. 1. Here, the bridge structure of the current sensing device with stepped copper bars is a differential full-bridge structure. As shown in FIG. 3, optionally, the first magnetic sensing unit 211 includes two magnetoresistive bridge arms 211a and 211b, and the second magnetic sensing 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. 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 sensing element connected in series and parallel. Optionally, the magnetoresistive sensing elements of the magnetoresistive bridge arms employ tunneling magnetoresistors (TMR), and optionally, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located on the same chip.

[0036] By combining the above analysis with the differential full-bridge structure shown in FIG. 3, we can see that there is a difference between the magnetic field generated by the stepped copper bar 1 at the position of the first magnetic sensing unit 211 and the magnetic field generated by the stepped copper bar 1 at the position of the second magnetic sensing unit 212. Specifically, the rightward magnetic field generated by the stepped copper bar 1 at the position of the first magnetic sensing unit 211 is stronger than the rightward magnetic field generated by the stepped copper bar 1 at the position of the second magnetic sensing unit 212. Because the sensitivity directions of the four magnetoresistive bridge arms 211a, 211b, 212a, and 212b are all rightward, the rightward magnetic field at the positions of the magnetoresistive bridge arms 211a and 211b is stronger than the rightward magnetic field at the positions of the magnetoresistive bridge arms 212a and 212b. Therefore, the resistance of the magnetoresistive bridge arms 211a and 211b is smaller than the resistance of the magnetoresistive bridge arms 212a and 212b. Therefore, the V2 voltage is greater than the V1 voltage, forming a differential voltage signal.

[0037] Optionally, the magnetic induction module 2 also includes a closed-loop signal conditioning circuit and a magnetic field feedback coil 22, where the closed-loop signal conditioning circuit, the magnetic field feedback coil 22, the first magnetic sensing unit 211, and the second magnetic sensing unit 212 constitute a closed-loop magnetic field feedback component, where 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 offset the differential-mode magnetic fields in opposite directions, whereby when dynamic equilibrium of the magnetic fields is reached, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 operate at equal common-mode magnetic field operating points, and then the feedback current of the magnetic field feedback coil 22 is sampled through a sampling resistor to form an output signal of the magnetic induction module 2. Alternatively, in other embodiments, the magnetic induction module also optionally includes an open-loop signal conditioning circuit that performs conditioning, amplification, temperature compensation, and linearity correction on the differential voltage signal.

[0038] In this embodiment, optionally, the magnetic field feedback coil 22 and the closed-loop signal conditioning circuit are integrated inside the magnetic sensing unit, for example, the first magnetic sensing unit 211 has the magnetic field feedback coil 22 and the closed-loop signal conditioning circuit integrated inside, and the second magnetic sensing unit 212 has the magnetic field feedback coil 22 and the closed-loop signal conditioning circuit integrated inside, and optionally, the closed-loop signal conditioning circuit is made in an ASIC application-specific integrated circuit.

[0039] The closed-loop signal conditioning circuit is used to condition, amplify, temperature compensate, and linearize the differential voltage signal generated between the first magnetic sensing unit 211 and the second magnetic sensing unit 212. After being amplified by the closed-loop signal conditioning circuit, the differential voltage signal passes through the magnetic field feedback coil 22 to generate a feedback magnetic field that offsets the differential-mode magnetic field in opposite directions. Once dynamic balance of the magnetic fields is achieved, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 operate at an equal common-mode magnetic field operating point. 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 forms the output signal of the current detection device with the stepped copper bar.

[0040] In this embodiment, the current sensing device with stepped copper bars provides a simple structure, small size, input / output electrical isolation, strong common-mode interference resistance, and the ability to measure DC and AC currents and large currents.

[0041] In another embodiment, the bridge structure of the current sensing device with stepped copper bars can also be selected as a differential half-bridge structure, in which the first magnetic sensing unit includes a magnetoresistive bridge arm, the second magnetic sensing unit includes a magnetoresistive bridge arm, and the two magnetoresistive bridge arms are electrically connected to form a differential half-bridge structure output, all of the magnetoresistive bridge arms have the same sensitivity direction and are composed of at least one magnetoresistive sensing element connected in series and parallel, and the first magnetic sensing unit and the second magnetic sensing unit are located on the same chip or two separate chips. Optionally, the magnetic induction module also includes an open-loop signal conditioning circuit that performs conditioning, amplification, temperature compensation, and linearity correction on the differential voltage signal. The operating principle of the circuit is similar to that of FIG. 3 and will not be described again here.

[0042] It should be noted that the measurement current range can be extended to some extent by simply using the stepped copper bar 1 to create the magnetic field, but the extent of the extension is still limited. Specifically, the common-mode magnetic field H CM By separating the common-mode magnetic field H through the cross section of the stepped copper bar 1, the measurement current range can be extended. CM has the same effect on the first magnetic sensing unit 211 and the second magnetic sensing unit 212, and in theory does not affect the output of the magnetic induction module 2, but due to the characteristics of the magnetoresistive sensing element itself, there are still certain linearity consistency problems and saturation problems.

[0043] Referring to FIG. 4, this figure is a schematic diagram of a voltage-magnetic field curve of a magnetoresistive sensing element. Optionally, the magnetoresistive sensing element of the magnetic induction module 2 is a tunnel magnetoresistor TMR. As shown in FIG. 4, there is a certain linear range on both sides of the zero magnetic field point, and as it approaches saturation, a change in the sensitivity of the tunnel magnetoresistor TMR occurs, which is reflected by a change in the slope of the curve in FIG. 4. Specifically, point A is within the linear range, point B is within the positive saturation approach range, and point C is within the negative saturation approach range.

[0044] According to the above equation (4), the common-mode magnetic field H in the three cases is CM The operating points of H are A, B, and C. 211 The operating points of H are A1, B1, and C1. 212 The operating points of H are A2, B2, and C2. 211 and H CM The difference is H DM and H 212 and H CM The difference is H DM It can be assumed that

[0045] At point A in the linear range, the sensitivity of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 is consistent, but at points B and C in the saturation approach range, the sensitivity of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 will have errors, that is, the slopes at B1 and B2 will be very different, and the slopes at C1 and C2 will be very different, which will affect the measurement accuracy of the current detection device.

[0046] Similarly, for input currents of different sizes, the generated common-mode magnetic field is different, so the sensitivity of the current detection device with stepped copper bars also has certain differences over the entire range, which creates certain problems regarding linearity consistency. For the reasons mentioned above, further extension of the measurement current range is limited.

[0047] Based on this, one embodiment of the present invention further provides another current detection device with a stepped copper bar. However, the current detection device with a stepped copper bar provided in this embodiment and the following embodiments differs from the above-mentioned embodiments in that a current shunt copper bar is introduced. The role of the current shunt copper bar in the current detection device with a stepped copper bar is, on the one hand, to further shunt the measured current and extend the measurement current range, and, on the other hand, to reduce and offset the common-mode magnetic field so that the operating point of the magnetic induction module returns from the approaching saturation range to the linear range. Therefore, the measurement current range can be significantly extended while taking into account the consistency of linearity.

[0048] Reference is now made to FIG. 5, which is a schematic diagram of another current sensing device with stepped copper bars in accordance with one embodiment of the present invention. As shown in FIG. 5 , the current detection device with a stepped copper bar provided in this embodiment includes a stepped copper bar 1, a current shunt copper bar 5, a magnetic induction module 2, and a circuit board 3, the magnetic induction module 2 is fixed on the circuit board 3, the stepped copper bar 1 and the current shunt copper bar 5 are connected in series and parallel to form a measured current input module, the magnetic induction module 2 and the circuit board 5 form a signal output module, the measured current input module is electrically insulated from the signal output module, the side of the stepped copper bar 1 facing the magnetic induction module 2 is stepped, the stepped copper bar 1 includes at least a first step 11 and a second step 12, the magnetic induction module 2 includes at least a first magnetic sensing unit 211 and a second magnetic sensing unit 212, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located on the same horizontal plane, and the horizontal plane is parallel to the plane on which the circuit board 3 is located. In a direction Z perpendicular to the circuit board 3, the first magnetic sensing unit 211 is located above the first step 11, and the second magnetic sensing unit 212 is located above the second step 12, and the current to be measured flows through a cross section perpendicular to the stepped copper bar 1 and the current shunt copper bar 5, generating a magnetic field at the position of the magnetic induction module 2, and the first magnetic sensing unit 211 and the second magnetic sensing 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 that forms the output signal of the current detection device with stepped copper bars.

[0049] In this embodiment, a current shunt copper bar 5 is introduced, and the stepped copper bar 1 and the current shunt copper bar 5 are located above and below the magnetic induction module 2. The magnetic induction module 2 is fixed on a circuit board 3, and the surface on which the circuit board 3 is located is optionally perpendicular to the Z direction. Along the Z direction, the stepped copper bar 1 and the current shunt copper bar 5 are located above and below the circuit board 3, and optionally, the stepped copper bar 1 is located below the circuit board 3, the current shunt copper bar 5 is located above the circuit board 3, and the magnetic induction module 2 is attached above the circuit board 3.

[0050] The stepped copper bar 1 and the current shunt copper bar 5 are connected in series and parallel to form a measured current input module, and the magnetic induction module 2 and the circuit board 5 form a signal output module. The measured current input module is electrically isolated from the signal output module. Because the plane on which the circuit board 3 is located is perpendicular to the Z direction, the cross section of the circuit board 3 is parallel to the XZ plane. Therefore, the cross sections of the stepped copper bar 1 and the current shunt copper bar 5 are both parallel to the XZ plane. The measured current flows through the cross section perpendicular to the stepped copper bar 1 and the current shunt copper bar 5. Optionally, the current shunt copper bar 5 can be connected in parallel with the stepped copper bar 1 to realize a common shunt of the measured current. Therefore, the measured current flows through the stepped copper bar 1 and the current shunt copper bar 5 in the same direction, both perpendicular to the paper surface and inward.

[0051] Optionally, in a direction Z perpendicular to the circuit board 3, the vertical projection of the current shunt copper bar 5 on the circuit board 3 covers the vertical projection of each magnetic sensing unit of the magnetic induction module 2 on the circuit board 3, the sensitivity direction of each magnetic sensing unit is the same, the sensitivity direction of the magnetic sensing unit is the same as or opposite to the direction of the magnetic field generated by the stepped copper bar 1 at the position of the magnetic sensing unit, and the sensitivity direction of the magnetic sensing unit is along the surface of the magnetic induction module 2 and perpendicular to the step-rising cross-sectional direction of the stepped copper bar 1. The current shunt copper bar 5 is located above the first magnetic sensing unit 211 and the second magnetic sensing unit 212, and both the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located within a uniform magnetic field region within the coverage range of the vertical projection of the current shunt copper bar 5 along the Z direction. Specifically, the first magnetic sensing unit 211 is located in the uniform magnetic field region above the first step 11 , and the second magnetic sensing unit 212 is located in the uniform magnetic field region above the second step 12 .

[0052] Optionally, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located on the same circuit board 3, or the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located on two separate circuit boards 3.

[0053] Optionally, the magnetic sensing unit of the magnetic induction module 2 is composed of any one of the magnetoresistive sensing elements: an anisotropic magnetoresistor AMR, a giant magnetoresistor GMR, a tunneling magnetoresistor TMR, and a colossal magnetoresistor CMR. Alternatively, optionally, the magnetic sensing unit of the magnetic induction module 2 is composed of any one of the magnetoresistive elements: a fluxgate, a giant magnetoimpedance GMI, and a magnetoelectric coupling device ME.

[0054] Optionally, the number of the current shunt copper bars is one or more, and along the vertical direction Z of the circuit board 3, any current shunt copper bar is located above the magnetic induction module 2 or below the stepped copper bar 1, and the vertical projection of the current shunt copper bar on the surface where the circuit board 3 is located covers each magnetic sensing unit of the magnetic induction module 2. Optionally, at the position of the magnetic induction module 2, the current direction of the current shunt copper bar is the same as or opposite to the current direction of the stepped copper bar 1, and in the current detection device with the stepped copper bar, the input range of the measured current of the current detection device with the stepped copper bar is adjusted by setting the series / parallel connection mode of the current shunt copper bar and the stepped copper bar 1, and / or the input range of the measured current of the current detection device with the stepped copper bar is adjusted by setting the number of the current shunt copper bars.

[0055] As shown in Figure 5, the current detection device with stepped copper bars introduces a current shunt copper bar 5, and the current shunt copper bar 1 is located above the magnetic induction module 2. At the position of the magnetic induction module 2, the current direction of the current shunt copper bar 5 is the same as that of the stepped copper bar 1, and the current shunt copper bar 5 shunts the current to be measured. By setting the series / parallel connection mode of the current shunt copper bar 5 and the stepped copper bar 1, the input range of the current to be measured of the current detection device with stepped copper bars can be adjusted, thereby further extending the measurement current range.

[0056] The current to be measured flows through the stepped copper bar 1 and the current shunt copper bar 5 in a current direction perpendicular to the cross section of the stepped copper bar 1 and the current shunt copper bar 5, generating a magnetic field at the position of the magnetic induction module 2, and the first magnetic sensing unit 211 and the second magnetic sensing 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 that forms the output signal of the current detection device with stepped copper bars. Here, the current shunt copper bar 5 generates a left-pointing common-mode magnetic field at the position of the magnetic sensing unit.

[0057] The specific analysis process is as follows. Referring to FIG. 6, this figure is a magnetic field simulation diagram of the current detection device with the stepped copper bar shown in FIG. 5. Comparing FIG. 6 with FIG. 2, it can be seen that near the step-up section, the magnetic fields in the same plane above the first step 11 and the second step 12 have obvious differences, and the magnetic field distribution is relatively uniform. However, the magnetic field curve shown in FIG. 6 has a significant downward shift. That is, the difference is that the left-pointing common-mode magnetic field generated by the current shunt copper bar 5 and the right-pointing common-mode magnetic field generated by the stepped copper bar 1 offset and reduce each other at the magnetic sensing unit position. Naturally, by adjusting the thickness and relative position of the current shunt copper bar 5, the offset common-mode magnetic fields can be in the same direction, zeroed out, or opposite directions.

[0058] The curves shown in Figure 6 will be taken as an example below. It can be seen that the offset common-mode magnetic fields of the current shunt copper bar 5 and the stepped copper bar 1 are in the same direction.

[0059] If the current flowing through the current shunt copper bar 5 is I5, then equation (5) is obtained. I in =I1+I5=I'1+ΔI1+I5(5)

[0060] Assuming that the rightward X direction is the positive direction of the magnetic field and that the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located in the uniform magnetic field region of the current shunt copper bar 5, Equation (6) is obtained according to Biot-Savart's law that the current-carrying wire generates a magnetic field. H 211 =k1I'1+k 21 ΔI1-k3I5; H 212 =k1I'1+k 22 ΔI1-k3I5(6) where k3 is the linear constant of the uniform magnetic field generated by the current I5 in the current shunt copper bar 5 at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212.

[0061] By performing equivalent transformation on equation (6), equation (7) is obtained.

[0062]

number

[0063] This also allows us to obtain equation (4). H 211 =H CM +H DM ; H 212 =H CM -H DM (4)

[0064] From equation (7), the magnetic fields generated by I′1 and I5 at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are in opposite directions, offsetting and reducing each other, and the differential mode magnetic field H DM without generating a common-mode magnetic field H CM It can be seen that the magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 generates only the current to be measured, thereby mainly playing a role in adjusting and increasing the current input range of the current sensing device with the stepped copper bar. Similarly, by combining Equation (7) and Equation (4), the magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 can be calculated as in The measured current is proportional to the differential mode magnetic field H DM It can be seen that this can be detected by measuring

[0065] Optionally, the magnetic induction module 2 also includes a closed-loop signal conditioning circuit and a magnetic field feedback coil, wherein the closed-loop signal conditioning circuit performs conditioning, amplification, temperature compensation, and linearity correction on the differential voltage signal, and the closed-loop signal conditioning circuit, the magnetic field feedback coil, the first magnetic sensing unit, and the second magnetic sensing unit form a closed-loop magnetic field feedback, and 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 to offset the differential mode magnetic field in opposite directions, and when dynamic equilibrium of the magnetic field is reached, the first magnetic sensing unit and the second magnetic sensing unit operate at an equal common mode magnetic field operating point, and then the feedback current of the magnetic field feedback coil is sampled through a sampling resistor to form an output signal of the magnetic induction module.

[0066] Optionally, the magnetic field feedback coil is integrated into one structure of the closed-loop signal conditioning circuit, the circuit board, each magnetic sensing unit of the magnetic induction module, and the magnetic induction module.

[0067] As shown in Fig. 5, the closed-loop signal conditioning circuit, the magnetic field feedback coil 22, the first magnetic sensing unit 211, and the second magnetic sensing unit 212 constitute a closed-loop magnetic field negative feedback. For the closed-loop magnetic field negative feedback, the magnetic field feedback coil 22 can be integrated into the closed-loop signal conditioning circuit, or into the circuit board 3 as shown in Fig. 5, or into the magnetic sensing unit as shown in Fig. 1, or into the ASIC dedicated integrated circuit, or into the magnetic induction module 2 as needed. The operating principles of the closed-loop magnetic field negative feedback components in the above different locations are generally the same.

[0068] Here, the working principle of the closed-loop magnetic field negative feedback component will be explained by taking as an example the magnetic field feedback coil 22 integrated into the circuit board 3 as shown in Fig. 5. The plane on which the magnetic field feedback coil 22 is located is parallel to the plane on which the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located. The magnetic field feedback coils 22 are symmetrically distributed along the cross section of the XZ plane on both sides of the center line, and the current direction on one side of the cross section is outward perpendicular to the paper plane, and the current direction on the other side of the cross section is inward perpendicular to the paper plane.

[0069] Regarding the direction of the feedback magnetic field generated by the magnetic field feedback coil 22, take an example where the rightward magnetic field in the first magnetic sensing unit 211 is greater than the rightward magnetic field in the second magnetic sensing unit 212. To offset the differential mode magnetic field in opposite directions, in the cross-sectional view shown in FIG. 5 , the current direction in the cross-sectional area of ​​the conductor of the magnetic field feedback coil 22 arranged horizontally below the first magnetic sensing unit 211 is outward perpendicular to the page, and the current direction in the cross-sectional area of ​​the conductor of the magnetic field feedback coil 22 arranged horizontally below the second magnetic sensing unit 212 is inward perpendicular to the page. Therefore, the magnetic field feedback coil 22 generates a leftward feedback magnetic field in the first magnetic sensing unit 211, and the magnetic field feedback coil 22 generates a rightward feedback magnetic field in the second magnetic sensing unit 212, thereby offsetting the differential mode magnetic field in opposite directions and achieving dynamic equilibrium of the magnetic field.

[0070] For cases where the magnetic field feedback coil 22 is integrated at other locations, the coil distribution or connections may be slightly different, but the magnetic field feedback principle, which will not be repeated here, is to use the distribution of the magnetic field feedback coil 22 to generate a magnetic field to offset the differential mode magnetic field.

[0071] Referring to Figure 7, this figure is a schematic diagram of the bridge structure of the current detection device with the stepped copper bar shown in Figure 5. As shown in Figure 7, optionally, the first magnetic sensing unit 211 is composed of a magnetoresistive bridge arm 211c, and the second magnetic sensing unit 212 is composed of a magnetoresistive bridge arm 212c. The magnetoresistive bridge arm is composed of one or more magnetoresistive sensing elements connected in series and parallel. The sensitive directions of the two magnetoresistive bridge arms are the same and are electrically connected to form a differential half-bridge structure.

[0072] 7, the two magnetoresistive bridge arms 211c and 212c have the same sensitivity direction, both in the horizontal rightward X direction, electrically forming a differential half-bridge structure. Optionally, the magnetoresistive sensing elements forming the magnetoresistive bridge arms 211c and 212c employ anisotropic magnetoresistors (AMR), and optionally, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located on two separate chips.

[0073] According to the above analysis, it can be seen that the current shunt copper bar 5 can only offset and reduce the common mode magnetic field, but does not generate a differential mode magnetic field. Therefore, the offset common mode magnetic field can be in the same direction, nullified, or opposite.

[0074] Assuming that the offset common-mode magnetic fields are in the same direction, the differential-mode magnetic field causes the rightward magnetic field at the position of the first magnetic sensing unit 211 to be larger than the rightward magnetic field at the position of the second magnetic sensing unit 212. Because the sensitivity directions of the two magnetoresistive bridge arms 211c and 212c are both rightward, in FIG. 7, the rightward magnetic field at the magnetoresistive bridge arm 211c is larger than the magnetic field at the magnetoresistive bridge arm 212c. Therefore, the resistance of the magnetoresistive bridge arm 211c is smaller than the resistance of the magnetoresistive bridge arm 212c, and a magnetic field-to-voltage conversion is realized. Therefore, Vout in FIG. 7 changes according to the current to be measured, forming a differential voltage signal.

[0075] Optionally, the 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-level discrete component circuit. The function and principle are the same as the closed-loop magnetic field negative feedback in FIG. 1 and will not be repeated here. In this embodiment, the output of the magnetic induction module 2 forms the output signal of the current detection device with a stepped copper bar.

[0076] In this embodiment, the stepped copper bar and the current shunt copper bar are connected in parallel to shunt the current to be measured, forming a current measurement input module. The stepped copper bar forms a differential-mode magnetic field, and the common-mode magnetic field formed by the current shunt copper bar offsets and reduces the common-mode magnetic field of the stepped copper bar, thereby extending the current measurement range. The first and second magnetic sensing units employ a differential half-bridge circuit, and the magnetic field feedback coil is integrated inside the circuit board. The current sensing device with the formed stepped copper bar has characteristics such as an adjustable common-mode magnetic field operating point, adaptability to various magnetic sensing units, adjustable sensitivity, input / output electrical isolation, strong common-mode interference resistance, and the ability to measure DC and AC currents and large currents.

[0077] Optionally, the current sensing device with stepped copper bars includes two or more current shunt copper bars, which are used in series and parallel connection to further adjust the common-mode magnetic field. Along the vertical direction of the circuit board, any current shunt copper bar is located above the magnetic induction module or below the stepped copper bar, and the vertical projection of the current shunt copper bar on the surface where the circuit board is located covers each magnetic sensing unit of the magnetic induction module. Optionally, at the position of the magnetic induction module, the current direction of the current shunt copper bar is the same direction or opposite to the current direction of the stepped copper bar. In the current sensing device with stepped copper bars, the input range of the measured current of the current sensing device with stepped copper bars is adjusted by setting the series / parallel connection mode of the current shunt copper bar and the stepped copper bar, and / or the input range of the measured current of the current sensing device with stepped copper bars is adjusted by setting the number of current shunt copper bars.

[0078] The following embodiment also provides an example in which the current detection device with a stepped copper bar includes two copper bars for current shunting. Note that the same content as the above embodiment including one copper bar for current shunting will not be described in detail.

[0079] 8, which is a schematic diagram of yet another current sensing device with stepped copper bars according to an embodiment of the present invention. As shown in FIG. 8, the current sensing device includes two current shunt copper bars 51 and 52, where the current shunt copper bar 51 is located above the magnetic induction module 2 and the current shunt copper bar 52 is located below the stepped copper bar 1. Optionally, a magnetic field feedback coil 22 is integrated inside the magnetic induction module 2.

[0080] Through the above analysis, it has been found that the offset common-mode magnetic field can be in the same direction, zeroed out, or in the opposite direction by adjusting the thickness and relative position of the current shunt copper bar 5 in FIG. 5 . As shown in FIG. 6 , the offset common-mode magnetic fields of the current shunt copper bar 5 and the stepped copper bar 1 are in the same direction. The position of the first current shunt copper bar 51 in FIG. 8 is the same as the position of the current shunt copper bar 5 in FIG. 5 . To further reduce the common-mode magnetic field, improve the linearity consistency, and extend the measurement current range, a newly introduced second current shunt copper bar 52 can be optionally positioned below the stepped copper bar 1. The current direction of the second current shunt copper bar 52 is outward perpendicular to the paper plane, while the current direction of the stepped copper bar 1 and the current shunt copper bar 51 is inward perpendicular to the paper plane.

[0081] In other embodiments, optionally, a newly introduced second current shunt copper bar can be positioned above the first current shunt copper bar, with the current direction in the second current shunt copper bar being perpendicular to the page and inward.

[0082] As shown in Figure 8, the current shunt copper bar 52 is introduced so as to be located below the stepped copper bar 1, and its current direction is perpendicular to the paper and outward. The current shunt copper bar 51 is connected in parallel with the stepped copper bar 1, and then connected in series with the current shunt copper bar 52. In this case, the main function of the current 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, so no shunting effect occurs.

[0083] Referring to Fig. 9, this figure is a magnetic field simulation diagram of the current detection device with the stepped copper bar shown in Fig. 8. The similarity between Fig. 9 and Fig. 6 is that near the step-rising section, the magnetic fields in the same plane above the first step 11 and the second step 12 have obvious differences and the magnetic field distribution is relatively uniform; the difference is that the magnetic field curve shown in Fig. 9 is shifted more significantly downward and closer to zero magnetic field. That is, the left-pointing common-mode magnetic field and the offset right-pointing common-mode magnetic field generated by the current shunt copper bar 52 at the position of the magnetic sensing unit are further offset and reduced.

[0084] The current flowing through the copper bar 51 for the current shunt is I 51 and the current flowing through the current shunt copper bar 52 is I 52 As a result, equation (8) is obtained. I in =I1+I 51 =I'1+ΔI1+I 51 ; I in =I 52 (8)

[0085] Assuming that the rightward X direction is the positive direction of the magnetic field and that the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located in the uniform magnetic field region of the current shunt copper bar 52, Equation (9) is obtained according to Biot-Savart's law that the current-carrying wire generates a magnetic field. H 211 =k1I'1+k 21 ΔI1-k3I 51 -k4I 52 ; H 212 =k1I'1+k 22 ΔI1-k3I 51 -k4I 52 (9) where k4 is the current I of the current shunt copper bar 52 at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212. 52 is the linear constant of the uniform magnetic field generated by

[0086] By performing equivalent transformation on equation (9), equation (10) is obtained.

[0087]

number

[0088] This also allows us to obtain equation (4). H 211 =H CM +H DM ; H 212 =H CM -H DM (4)

[0089] From equation (10), I′1 and I′2 are calculated at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212. 51、 and I 52 The magnetic fields generated by the axial magnetic field H are opposite in direction and offset and reduce each other. DM without generating a common-mode magnetic field H CM It can be seen that the magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 generates only the current to be measured, thereby mainly playing a role in adjusting and increasing the current input range of the current sensing device with the stepped copper bar. Similarly, by combining Equation (10) and Equation (4), the magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 can be calculated as in The measured current is proportional to the differential mode magnetic field H DM It can be seen that this can be detected by measuring

[0090] The magnetoresistive bridge arm of the current detection device with the stepped copper bar shown in Fig. 8 may adopt a differential half-bridge structure as shown in Fig. 7, in which the current shunt copper bar 51 and the current shunt copper bar 52 offset and reduce only the common-mode magnetic field without generating a differential-mode magnetic field, so that the output signal Vout of the differential half-bridge structure changes according to the measured current to form a differential voltage signal.

[0091] Optionally, the magnetic induction module 2 also includes a magnetic field feedback coil 22 integrated within the magnetic sensing unit 2 and a closed-loop signal conditioning circuit using PCB board-level discrete component circuitry. The output of the magnetic induction module 2 forms the output signal of a current detection device with a stepped copper bar.

[0092] In this embodiment, the first current shunt copper bar and the stepped copper bar are connected in parallel, and then further connected in series with the second current shunt copper bar to form a current input module under test. The stepped copper bar forms a differential mode magnetic field, and the common mode magnetic field formed by the first current shunt copper bar and the second current shunt copper bar offsets and reduces the common mode magnetic field of the stepped copper bar, thereby extending the measurement range. The current detection device with the stepped copper bar has the following characteristics: an adjustable common mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, input / output electrical isolation, strong common mode interference resistance, the ability to measure DC and AC currents, and the ability to measure large currents.

[0093] The following embodiments also provide an example in which the current detection device with a stepped copper bar includes one current shunt copper bar. Please note that the same content as the above-mentioned embodiments including one or two current shunt copper bars will not be described in detail. Furthermore, optionally, the current detection device with a stepped copper bar includes one current shunt copper bar that may be located below the stepped copper bar, and the current direction in the current shunt copper bar is outward and perpendicular to the plane of the paper. Referring to FIG. 10 , this figure is a schematic diagram of yet another current sensor with a stepped copper bar according to an embodiment of the present invention. As shown in FIG. 10 , the current detection device includes one current shunt copper bar 52 located below the stepped copper bar 1, and the current shunt copper bar 52 is directly connected in series with the stepped copper bar 1, and the current direction in the stepped copper bar 1 is inward and perpendicular to the plane of the paper. The specific analysis process is as follows:

[0094] The current flowing through the copper bar 52 for the current shunt is I 52 As a result, equation (11) is obtained. I in =I1=I 52 (11)

[0095] Assuming that the rightward X direction is the positive direction of the magnetic field and that the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located in the uniform magnetic field region of the current shunt copper bar 52, Equation (12) is obtained according to Biot-Savart's law that the current-carrying wire generates a magnetic field. H 211 =k1I'1+k 21 ΔI1-k4I 52 ; H 212 =k1I'1+k 22 ΔI1-k4I 52 (12)

[0096] By performing equivalent transformation on equation (12), equation (13) is obtained.

[0097]

number

number

[0098] This also allows us to obtain equation (4). H 211 =H CM +H DM ; H 212 =H CM -H DM (4)

[0099] I′1 and I′2 at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212. 52 The magnetic fields generated by the axial magnetic field H are opposite in direction and offset and reduce each other. DMwithout generating a common-mode magnetic field H CM It can be seen that the magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 generates only the current to be measured, thereby mainly playing a role in adjusting and increasing the current input range of the current sensing device with the stepped copper bar. Similarly, by combining Equation (13) and Equation (4), the magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 can be calculated as in The measured current is proportional to the differential mode magnetic field H DM It can be seen that this can be detected by measuring

[0100] Optionally, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are two separately located giant magneto-impedance (GMI) units with rightward sensitivity directions. According to the above analysis, there is a difference between the magnetic fields generated by the stepped copper bar 1 at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212, and the current shunt copper bar 52 can offset and reduce only the common-mode magnetic field without generating a differential-mode magnetic field. Therefore, there is a difference between the magnetic fields induced by the two separately located giant magneto-impedance GMIs, which can generate a differential voltage signal.

[0101] Optionally, the magnetic induction module also includes an open-loop signal conditioning circuit that 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 sensing unit 211 and the second magnetic sensing unit 212. The output of the magnetic induction module 2 forms the output signal of the current detection device with the stepped copper bar.

[0102] In this embodiment, a current shunt copper bar is connected in series with a stepped copper bar, and the two current directions are opposite to each other. The stepped copper bar forms a differential mode magnetic field, and the common mode magnetic field formed by the current shunt copper bar offsets and reduces the common mode magnetic field of the stepped copper bar, thereby extending the measurement current range. The current detection device of this embodiment has characteristics such as an adjustable common mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, electrical isolation between input and output, strong common mode interference resistance, the ability to measure DC and AC currents, and the ability to measure large currents.

[0103] The above-described embodiments including copper bars for current shunting are merely exemplary. For example, in other embodiments, the current detection device may include copper bars for current shunting. The first magnetic sensing unit is composed of two magnetoresistive bridge arms, and the second magnetic sensing unit is composed of two magnetoresistive bridge arms. The magnetoresistive bridge arms are composed of one or more magnetoresistive sensing elements connected in series and parallel. The four magnetoresistive bridge arms have the same sensitivity direction and are electrically connected to form a differential full-bridge structure. The first magnetic sensing unit and the second magnetic sensing unit are located on the same chip or two separate chips. Clearly, there are many other embodiments including copper bars for current shunting, and these are not limited to the exemplary embodiments described above.

[0104] Although there are many embodiments that include a copper bar for the current shunt, it can be seen that after introducing one or more copper bars for the current shunt and adopting the series-parallel connection method, the analysis and calculation are almost the same as the analysis process described above. In addition, regardless of which case is adopted, for a current sensing device with a stepped copper bar incorporating a copper bar for the current shunt, the ideal condition in most applications is that the common-mode magnetic field is completely offset. In this case, the measurement current range of the current sensing device with a stepped copper bar can be maximized, that is, the differential-mode magnetic field can be fully extended to the operating range of the magnetoresistive sensing element, thereby obtaining the following equations (14) and (15):

[0105]

number

number

[0106] Furthermore, in an ideal situation, the magnetic field generated by the current ΔI1 in the upper rectangle at the location of the second magnetic sensing unit 42 is very small, and k 22 = 0, and thus the above equation (14) can be simplified to the following equations (16) and (17). H CM =0

[0107]

number

[0108] The magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 generates a current to be measured I inThe measured current is proportional to the differential mode magnetic field H DM Furthermore, by combining equations (16) and (17), under ideal conditions, the common-mode magnetic field H CM is fully offset, limiting the operating range of the magnetoresistive sensing element to the differential mode magnetic field H DM can be fully covered to provide the maximum measurement current range.

[0109] It should be noted that the above description is only a preferred embodiment and uses the technical principle of the present invention. Those skilled in the art should understand that the present invention is not limited to the specific embodiments described herein, and that various obvious modifications, rearrangements, mutual combinations, and substitutions may be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention is described in detail through the above embodiments, the present invention is not limited to the above embodiments only, and many other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is defined by the appended claims.

Claims

1. A circuit board; a magnetic induction module fixed on the circuit board, the magnetic induction module including at least a first magnetic sensing unit and a second magnetic sensing unit, the first magnetic sensing unit and the second magnetic sensing unit being located on the same horizontal plane, the horizontal plane being parallel to a surface on which the circuit board is located; a stepped copper bar, the side of the stepped copper bar facing the magnetic induction module being stepped, the stepped copper bar comprising at least a first step portion and a second step portion different from the first step portion, the first magnetic sensing unit being located above the first step portion and the second magnetic sensing unit being located above the second step portion in a direction perpendicular to the circuit board, and the stepped copper bar being electrically insulated from the magnetic induction module; a current to be measured flows through a stepped cross section perpendicular to the stepped copper bar, and the first magnetic sensing unit and the second magnetic sensing unit differentially sense a differential mode magnetic field generated by the current to be measured flowing through the stepped copper bar, and generate and output a differential voltage signal; A current detection device having a stepped copper bar, wherein the stepped copper bar is electrically insulated from the circuit board.

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

3. 2. The current detection device with stepped copper bar according to claim 1, further comprising a mechanical support housing that encases, secures, and supports the magnetic induction module and the stepped copper bar.

4. the first magnetic sensing unit includes at least one magnetoresistive bridge arm, and the second magnetic sensing unit includes at least one magnetoresistive bridge arm; 2. The current detection device with stepped copper bars as claimed in claim 1, characterized in that the magnetoresistive bridge arms of the first magnetic sensing unit and the magnetoresistive bridge arms of the second magnetic sensing unit are electrically connected to form a differential half-bridge structure output or connected to form a differential full-bridge structure output, all magnetoresistive bridge arms have the same sensitivity direction, the magnetoresistive bridge arms are formed by connecting at least one magnetoresistive sensing element in series and parallel, and the first magnetic sensing unit and the second magnetic sensing unit are located on the same chip or two separate chips.

5. the magnetic induction module also 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 sensing unit, and the second magnetic sensing unit constitute a closed-loop magnetic field feedback component, and 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 to offset the differential mode magnetic field in opposite directions, and when a dynamic equilibrium of the magnetic field is reached, the first magnetic sensing unit and the second magnetic sensing unit operate at an equal common mode magnetic field operating point, and then the feedback current of the magnetic field feedback coil is sampled through a sampling resistor to form an output signal of the magnetic induction module; or 2. The current sensing device with stepped copper bars of claim 1, wherein the magnetic induction module also includes an open-loop signal conditioning circuit that performs conditioning, amplification, temperature compensation, and linearity correction on the differential voltage signal.

6. A current detection device having a stepped copper bar, a stepped copper bar, a copper bar for current shunting, a magnetic induction module, and a circuit board, the magnetic induction module being fixed on the circuit board; the stepped copper bar and the current shunt copper bar are connected in series or in parallel to form a measured current input module, the magnetic induction module and the circuit board form a signal output module, and the measured current input module is electrically insulated from the signal output module; a side of the stepped copper bar facing the magnetic induction module is stepped, the stepped copper bar having at least a first step portion and a second step portion; the magnetic induction module includes at least a first magnetic sensing unit and a second magnetic sensing unit, the first magnetic sensing unit and the second magnetic sensing unit are located on the same horizontal plane, the horizontal plane is parallel to a surface on which the circuit board is located, and in a direction perpendicular to the circuit board, the first magnetic sensing unit is located above the first step portion and the second magnetic sensing unit is located above the second step portion; a current to be measured flows through a stepped cross section perpendicular to the stepped copper bar and the current shunt copper bar, generating a magnetic field at the position of the magnetic induction module; the first magnetic sensing unit and the second magnetic sensing 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 differential voltage signal that forms an output signal of the current detection device with a stepped copper bar; A current detection device having a stepped copper bar, wherein the stepped copper bar is electrically insulated from the circuit board.

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

8. the first magnetic sensing unit and the second magnetic sensing unit are located on the same circuit board; or 7. The current detection device with stepped copper bar according to claim 6, wherein the first magnetic sensing unit and the second magnetic sensing unit are located on two separate circuit boards.

9. the first magnetic sensing unit is comprised of a magnetoresistive bridge arm, the second magnetic sensing unit is comprised of a magnetoresistive bridge arm, the magnetoresistive bridge arm is comprised of one or more magnetoresistive sensing elements connected in series and parallel, two of the magnetoresistive bridge arms have the same sensitivity direction and are electrically connected to form a differential half-bridge structure; or the first magnetic sensing unit is composed of two magnetoresistive bridge arms, the second magnetic sensing unit is composed of two magnetoresistive bridge arms, each of the magnetoresistive bridge arms is composed of one or more magnetoresistive sensing elements connected in series and parallel, and the four magnetoresistive bridge arms have the same sensitivity direction and are electrically connected to form a differential full-bridge structure; 7. The current detection device with stepped copper bars according to claim 6, wherein the first magnetic sensing unit and the second magnetic sensing unit are located on the same chip or two separate chips.

10. 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; or 7. The current detection device with stepped copper bars of claim 6, wherein the magnetic induction module also includes a closed-loop signal conditioning circuit and a magnetic field feedback coil, the closed-loop signal conditioning circuit performs conditioning, amplification, temperature compensation, and linearity correction on the differential voltage signal, the closed-loop signal conditioning circuit, the magnetic field feedback coil, the first magnetic sensing unit, and the second magnetic sensing unit establish a closed-loop magnetic field feedback, 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 to offset differential mode magnetic fields in opposite directions, when magnetic field dynamic equilibrium is reached, the first magnetic sensing unit and the second magnetic sensing unit operate at equal common mode magnetic field operating points, and then a feedback current of the magnetic field feedback coil is sampled through a sampling resistor to form an output signal of the magnetic induction module.

11. The number of the current shunt copper bars is one or more; 11. A current detection device with a stepped copper bar according to claim 6, wherein along the vertical direction of the circuit board, any current shunt copper bar is located above the magnetic induction module or below the stepped copper bar, and the vertical projection of the current shunt copper bar on the surface on which the circuit board is located covers each magnetic sensing unit of the magnetic induction module.

12. At the position of the magnetic induction module, the current direction of the current shunt copper bar is the same as or opposite to the current direction of the stepped copper bar; 12. The current detection device with stepped copper bars according to claim 11, wherein the input range of the current to be measured of the current detection device with stepped copper bars is adjusted by setting the series / parallel connection mode of the current shunt copper bars and the stepped copper bars, and / or the input range of the current to be measured of the current detection device with stepped copper bars is adjusted by setting the number of the current shunt copper bars.

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