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 DISCLOSURE

[0002] 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 technology, detection technology, power monitoring systems, inverter power supplies, electric vehicles, and other fields. At present, 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, optical fiber 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. Basically, a shunt is a resistor with a very low resistance, which converts the 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 measuring loop of the shunt, and there is no electrical isolation between the signal output and the current loop being measured, so there is mutual interference between the two. Shunts are suitable for low frequency and low power, they cannot measure the current 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 current. Closed type current transformers require the busbar to be removed before installation or disassembly, and have a complex structure, while the magnetic circuit of open type current transformers has an air gap, so the product itself has a relatively large error and large size. Rogowski coils are similar to current transformers and adopt an air-core design. Rogowski coils can be directly attached to the conductor to be measured and are suitable for measuring AC currents in a wide frequency range, but cannot measure DC currents. Rogowski coils also have low sensitivity and large size.

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

[0006] The magnetic current sensor uses different structural designs of current-carrying conductor materials to generate a magnetic field in space, and then uses various magnetic induction elements to sense the magnetic field and output a voltage signal to realize current detection. Interference greatly affects the current measurement accuracy. The current measurement accuracy of the magnetic current sensor can be improved by improving the anti-interference ability of the magnetic current sensor. The design commonly adopted for the anti-interference ability of existing magnetic current sensors is to use the difference in the magnetic fields generated by current-carrying conductors at different positions in space to carry out differential testing of the magnetic field through the magnetic induction element.

[0007] 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 problem of magnetic leakage in the air gap of the iron core, and the volume and weight of the magnetic ring structure are large. Since the magnetic field lines inside the same 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 is easily saturated when measuring large currents. (2) A method using a U-shaped wire to generate differential signals in opposite directions, or using a copper bar with a neck recess as the signal input, or using a measured copper busbar wire with a rectangular or rounded rectangular cross section as the signal input. However, when the current is large, the magnetic field generated by the measured current passing through the above wire is directly used as the input signal of the magnetoresistance sensing element for differential detection, and therefore, when measuring large currents, the common mode magnetic field will saturate the magnetoresistance sensor chip, resulting in a limited input range. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE DISCLOSURE The 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, comprising: 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 with 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 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 including the stepped copper bar, The stepped copper bar and the copper bar for 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, the stepped copper bar having at least a first step and a second step; the magnetic induction module at least comprises 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 plane 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 current shunting, generating a magnetic field at the position of a 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 the current detection device with stepped copper bar provided by the 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, and since 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 measured current can flow through the lower rectangle of the stepped copper bar in the direction away from the magnetic induction module to form a common mode magnetic field, and at the same time, the size of the differential mode magnetic field can be adjusted and controlled so that the measurement current range can be extended. The current detection device with stepped copper bar has the characteristics of adjustable common mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, input and output electrical isolation, strong common mode interference resistance ability, DC and AC current measurement ability, and large current measurement ability.

[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, all of which are within the scope of the claims of the present invention. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a schematic diagram illustrating a current sensing device with a stepped copper bar according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a magnetic field simulation diagram of a current detection device with a stepped copper bar shown in FIG. 1. [Diagram 3] FIG. 2 is a schematic diagram showing a bridge structure of a current detection device with stepped copper bars shown in FIG. 1 . [Figure 4] FIG. 1 is a schematic diagram showing voltage vs. magnetic field curves of a magnetoresistive sensing element current detection device. [Diagram 5] FIG. 2 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 a current detection device with a stepped copper bar shown in FIG. 5. [Figure 7] FIG. 6 is a schematic diagram showing a bridge structure of a current detection device with a stepped copper bar shown in FIG. 5 . [Figure 8] FIG. 13 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 a current detection device with a stepped copper bar shown in FIG. 8. [Figure 10] FIG. 13 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 PREFERRED EMBODIMENTS

[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 of them. Based on the basic concept 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 an 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, the first step 11 and the second step 11 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 sensing device with stepped copper bar comprises a stepped copper bar and a magnetic induction module, so the current sensing device with stepped copper bar is also a magnetoresistive current sensing 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 sensing device with stepped copper bar also includes a mechanical support housing 4 that encases, secures and supports the magnetic induction module 2 and the stepped copper bar 1. The mechanical support housing 4 not only encases, secures and supports various parts of the current sensing device with stepped copper bar, but also provides an external interface.

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

[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. Since the direction of the magnetic field generated by the stepped copper bar 1 at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 is the same as the sensitivity direction of the magnetic sensing units, the direction of the magnetic field generated by the stepped copper bar 1 at the positions 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. It can be understood that the sensitivity direction of the magnetic sensing unit shown in the right-facing is merely an example, and practitioners in the relevant field can reasonably design the sensitivity direction of the magnetic sensing unit according to product requirements, and is 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 and 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 I1is 50A, the width of the cross section of the stepped copper bar 1 along the Z direction is 10mm, and the magnetic induction module 2 is located at a horizontal plane position 0.6mm above the stepped copper bar 1. When the current to be measured flows through the stepped copper bar 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 Figure 2, which shows that near the step rise 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.

[0024] Assume that 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. 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, i.e., 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., into upper and lower rectangular cross-sectional parts according to the first step 11 and the 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 rightward 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 position of the second magnetic sensing unit 212. 212 varies linearly with 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 rectangle at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212; k 21 is the linear constant of the magnetic field generated by the current ΔI1 of the upper rectangle 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 in the upper rectangle at the position of the second magnetic sensing unit 212.

[0028] By performing an equivalent transformation on Equation (2), the magnetic field at the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212 is expressed as a 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 This can be converted into a convolution equation, yielding equation (4). 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 the current detection device with stepped copper bar provided by the 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, and since the current density of the stepped copper bar is the same across the cross section, by adjusting the height of the first step and the second step, most of the measured current flows through the lower rectangle on the surface of the stepped copper bar in the direction away from the magnetic induction module to form a common mode magnetic field, and at the same time, the size of the differential mode magnetic field can be adjusted and controlled so that the measurement current range can be extended. The current detection device with stepped copper bar has the characteristics of adjustable common mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, electrical isolation of input and output, strong common mode interference resistance, and large AC and DC current measurement capability.

[0033] Optionally, the magnetic sensing unit of the magnetic induction module is composed of any of the magnetoresistance sensing elements: anisotropic magnetoresistor AMR, giant magnetoresistor GMR, tunnel magnetoresistor TMR, and 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 in 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 magnetoresistance bridge arms 211a and 211b, the second magnetic sensing unit 212 includes two magnetoresistance bridge arms 212a and 212b, and the four magnetoresistance bridge arms 211a, 211b, 212a, and 212b are electrically connected to form a differential full-bridge structure. The sensitivity directions of the four magnetoresistance bridge arms 211a, 211b, 212a, and 212b are the same, and all are horizontally to the right in the X direction. Each magnetoresistance bridge arm is composed of at least one magnetoresistance sensing element connected in series and parallel. Optionally, the magnetoresistive sensing elements of the magnetoresistive bridge arms adopt tunnel 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, it can be seen 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 larger than the rightward magnetic field generated by the stepped copper bar 1 at the position of the second magnetic sensing unit 212. Since the sensitivity directions of the four magnetoresistance bridge arms 211a, 211b, 212a, and 212b are all rightward, the rightward magnetic field at the positions of the magnetoresistance bridge arms 211a and 211b is larger than the rightward magnetic field at the positions of the magnetoresistance bridge arms 212a and 212b. Therefore, the resistance of the magnetoresistance bridge arms 211a and 211b is smaller than the resistance of the magnetoresistance bridge arms 212a and 212b. Therefore, it is obtained that 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 field in opposite directions, and when the dynamic equilibrium of the magnetic field is reached, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 operate at an equal common mode magnetic field operating point, 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, optionally, 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.

[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, 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 perform conditioning, amplification, temperature compensation, and linearity correction on the differential voltage signal generated between the first magnetic sensing unit 211 and the second magnetic sensing unit 212. After the differential voltage signal is amplified by the closed-loop signal conditioning circuit, it passes through the magnetic field feedback coil 22 to generate a feedback magnetic field to offset the differential mode magnetic field in the opposite direction. When the dynamic balance of the magnetic field is achieved, the first magnetic sensing unit 211 and the second magnetic sensing 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 forms the output signal of the current detection device with the stepped copper bar.

[0040] In the current sensing device with stepped copper bar provided in this embodiment, the first magnetic sensing unit and the second magnetic sensing unit of the magnetic induction module adopt a full-bridge circuit structure and are located on the same chip, which can improve the anti-interference ability and consistency, and the stepped shape of the stepped copper bar can enable the magnetic induction module to form a differential mode magnetic field, and the magnetic field feedback coil is integrated inside the magnetic sensing unit. On this basis, the current sensing device with stepped copper bar has the characteristics of simple structure, small size, electrical isolation of input and output, strong anti-common mode interference ability, ability to measure DC and AC current, and ability to measure large current.

[0041] In other embodiments, 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 magnetoresistance bridge arm, the second magnetic sensing unit includes a magnetoresistance bridge arm, and the two magnetoresistance bridge arms are electrically connected to form a differential half-bridge structure output, and all the magnetoresistance bridge arms have the same sensitivity direction and are composed of at least one magnetoresistance 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 on two separate chips. Optionally, 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. The working principle of the circuit is similar to that of FIG. 3 and will not be described again here.

[0042] It should be noted that by simply using the stepped copper bar 1 to shape the magnetic field, the measurement current range can be extended to some extent, but the degree of extension is still limited. Specifically, the common-mode magnetic field H CM By isolating 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 will not affect the output of the magnetic induction module 2, but due to the characteristics of the magnetoresistance 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 the voltage-magnetic field curve of a magnetoresistance sensing element. Optionally, the magnetoresistance sensing element of the magnetic induction module 2 is a tunnel magnetoresistor TMR. As shown in FIG. 4, there is a certain range of linear sections on both sides of the magnetic field zero point, and as it approaches saturation, there will be a change in the sensitivity of the tunnel magnetoresistor TMR, which is reflected by the change in the slope of the curve in FIG. 4. Specifically, point A is in the linear range, point B is in the positive saturation approach range, and point C is in the negative saturation approach range.

[0044] According to the above formula (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 sensitivity of the current sensing device with stepped copper bars will also have a certain difference over the entire range, since the generated common mode magnetic field will be different, which will cause certain problems regarding the consistency of linearity. For the reasons mentioned above, the further extension of the measurement current range is limited.

[0047] Based on this, an embodiment of the present invention further provides another current sensing device with stepped copper bars, but the current sensing device with stepped copper bars provided in this embodiment and the following embodiments differs from any of the above-mentioned embodiments in that a current shunting copper bar is introduced. The role of the current shunting copper bar in the current sensing device with stepped copper bars 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 linearity consistency.

[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 an embodiment of the present invention. As shown in FIG. 5, the current detection device with stepped copper bar provided in this embodiment includes a stepped copper bar 1, a copper bar for current shunting 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 copper bar for current shunting 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 copper bar for current shunt 5 to generate 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 measured current 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 copper bar for current shunting 5 is introduced, and the stepped copper bar 1 and the copper bar for current shunting 5 are located on 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 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 copper bar for current shunting 5 are located on the upper and lower sides of the circuit board 3, and optionally, the stepped copper bar 1 is located below the circuit board 3, the copper bar for current shunting 5 is located above the circuit board 3, and the magnetic induction module 2 is mounted 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, and the measured current input module is electrically isolated from the signal output module. The plane on which the circuit board 3 is located is perpendicular to the Z direction, so that the cross section of the circuit board 3 is parallel to the XZ plane, and 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 sections 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, so that the measured current flows in the same direction through the stepped copper bar 1 and the current shunt copper bar 5, both perpendicular to the paper 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 rise 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 in 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 magnetoresistance sensing elements, which are anisotropic magnetoresistor AMR, giant magnetoresistor GMR, tunnel magnetoresistor TMR, and colossal magnetoresistor CMR, or, optionally, the magnetic sensing unit of the magnetic induction module 2 is composed of any one of the magnetic induction elements, which are fluxgate, giant magnetoimpedance GMI, and 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 FIG. 5, the current detection device with stepped copper bar 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 bar can be adjusted, thereby further extending the measurement current range.

[0056] The measured current flows through the stepped copper bar 1 and the current shunt copper bar 5 with 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 measured current flowing through the measured current input module, and generate a voltage signal forming the output signal of the current detection device with stepped copper bars, where the current shunt copper bar 5 generates a left-pointing common mode magnetic field at the position of the magnetic sensing units.

[0057] The specific analysis process is as follows. Refer to FIG. 6, which 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 rise section, the magnetic field in the same plane above the first step 11 and the second step 12 has obvious difference, and the magnetic field distribution is relatively uniform, and the magnetic field curve shown in FIG. 6 has a significant downward shift, that is, there is a difference that the left-handed common mode magnetic field generated by the current shunt copper bar 5 and the right-handed common mode magnetic field generated by the stepped copper bar 1 at the position of the magnetic sensing unit offset and reduce each other. Of course, by adjusting the thickness and relative position of the current shunt copper bar 5, the offset common mode magnetic field can be in the same direction, zeroed out, or opposite direction.

[0058] In the following, the curve shown in Figure 6 will be taken as an example. 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 of the same direction.

[0059] Equation (5) is obtained by defining the current flowing through the current shunt copper bar 5 as I5. 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 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, according to the Biot-Savart law that the current-carrying wire generates a magnetic field, Equation (6) is obtained. 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 an 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 and offset and reduce 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 I, thereby mainly playing a role in adjusting and increasing the current input range of the current detection 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 generates only the current to be measured 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

[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 establish 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 construct 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 integrated into the circuit board 3 as shown in Fig. 5, or integrated into the magnetic sensing unit as shown in Fig. 1, or integrated into the ASIC dedicated integrated circuit, or integrated into the magnetic induction module 2 as required. The working principles of the closed-loop magnetic field negative feedback components in different positions mentioned above are approximately the same.

[0068] Here, the working principle of the closed-loop magnetic field negative feedback component is explained by taking the magnetic field feedback coil 22 integrated in the circuit board 3 as an example, as shown in Fig. 5. The plane where the magnetic field feedback coil 22 is located is parallel to the plane where the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are located. The magnetic field feedback coil 22 is 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] With respect to the direction of the feedback magnetic field generated by the magnetic field feedback coil 22, take an example in which the rightward magnetic field in the first magnetic sensing unit 211 is larger than the rightward magnetic field in the second magnetic sensing unit 212. In order to offset the differential mode magnetic field in the opposite direction, in the cross-sectional view shown in Fig. 5, the current direction of 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 paper plane, and the current direction of 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 paper plane. Thus, 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 the opposite direction 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 that the distribution of the magnetic field feedback coil 22 is used to generate a magnetic field to offset the differential mode magnetic field.

[0071] Referring to Fig. 7, this figure is a schematic diagram of a bridge structure of a current sensing device with a stepped copper bar shown in Fig. 5. As shown in Fig. 7, optionally, the first magnetic sensing unit 211 is composed of a magnetoresistance bridge arm 211c, and the second magnetic sensing unit 212 is composed of a magnetoresistance bridge arm 212c. The magnetoresistance bridge arm is composed of one or more magnetoresistance sensing elements connected in series and parallel. The sensitive directions of the two magnetoresistance 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 adopt 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 may be in the same direction, nullified, or opposite direction.

[0074] Assuming that the offset common mode magnetic fields are of the same direction, the differential mode magnetic field makes the rightward magnetic field at the position of the first magnetic sensing unit 211 larger than the rightward magnetic field at the position of the second magnetic sensing unit 212. Since the sensitivity directions of the two magnetoresistance bridge arms 211c and 212c are both rightward, in FIG. 7, the rightward magnetic field at the magnetoresistance bridge arm 211c is larger than the magnetic field at the magnetoresistance bridge arm 212c. Therefore, the resistance of the magnetoresistance bridge arm 211c is smaller than the resistance of the magnetoresistance bridge arm 212c, and a magnetic field-to-voltage conversion is realized. Therefore, Vout in FIG. 7 changes according to the measured current to form 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 board-level discrete component circuit. Its 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 stepped copper bar.

[0076] In this embodiment, the stepped copper bar and the current shunt copper bar are connected in parallel to shunt the measured current to form a measured current 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 measurement current range. The first magnetic sensing unit and the second magnetic sensing unit adopt a differential half-bridge circuit, and the magnetic field feedback coil is integrated inside the circuit board. The current detection device with the formed stepped copper bar has the characteristics of adjustable common mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, input and output electrical isolation, strong common mode interference resistance ability, DC and AC current measurement ability, and large current measurement ability.

[0077] Optionally, the current sensing device with stepped copper bars includes two or more current shunt copper bars, and the two or more current shunt copper bars 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 direction to the current direction of the stepped copper bar, and 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 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 is not 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, the magnetic field feedback coil 22 is integrated inside the magnetic induction module 2.

[0080] Through the above analysis, it is known that the offset common mode magnetic field can be in the same direction, nullified, 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 field of the current shunt copper bar 5 and the stepped copper bar 1 is in the same direction. The position of the first current shunt copper bar 51 in FIG. 8 is the same as that of the current shunt copper bar 5 in FIG. 5. In order 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 located below the stepped copper bar 1, and the current direction of the second current shunt copper bar 52 is outward perpendicular to the paper, and the current direction of the stepped copper bar 1 and the current shunt copper bar 51 is inward perpendicular to the paper.

[0081] In other embodiments, optionally, a newly introduced second current shunt copper bar can be placed 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, and 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. At this time, 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 measured current, 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 field in the same plane above the first step 11 and the second step 12 has obvious difference and the magnetic field distribution is relatively uniform, and the difference is that the magnetic field curve shown in Fig. 9 is shifted downward more significantly and closer to zero magnetic field. That is, the left common mode magnetic field and the offset right common mode magnetic field generated by the current shunt copper bar 52 at the magnetic sensing unit position are further offset and reduced.

[0084] The current flowing through the copper bar 51 for the current shunt is I 51 The current flowing through the current shunt copper bar 52 is I 52 As a result, we obtain equation (8). 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 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, according to the Biot-Savart law that the current-carrying wire generates a magnetic field, Equation (9) is obtained. 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 an 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 51、 and I 52 The magnetic fields generated by the axial magnetic field H are in opposite directions and offset and reduce 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 I, thereby mainly playing a role in adjusting and increasing the current input range of the current detection 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 generates only the current to be measured 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

[0090] The magnetoresistance bridge arm of the current sensing device with stepped copper bars 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 stepped copper bars.

[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 measured current input module, 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 current range. The current detection device with stepped copper bar has the following characteristics: adjustable common mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, input and output electrical isolation, strong common mode interference resistance ability, DC and AC current measurement ability, and large current measurement ability.

[0093] The following embodiment also provides a case where the current detection device with stepped copper bars includes one current shunt copper bar. Please note that the same contents as the above-mentioned embodiment including one or two current shunt copper bars will not be described in detail. In addition, optionally, the current detection device with stepped copper bars 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 perpendicular to the paper and faces outward. Refer to FIG. 10, which is a schematic diagram of yet another current sensor with stepped copper bars 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 perpendicular to the paper and faces inward. 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, we obtain equation (11). I in =I1=I 52 (11)

[0095] Assuming that the rightward X direction is the positive direction of the magnetic field and 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, according to the Biot-Savart law that the current-carrying wire generates a magnetic field, Equation (12) is obtained. H 211 =k1I'1+k 21 ΔI1-k4I 52 ; H 212 =k1I'1+k 22 ΔI1-k4I 52 (12)

[0096] By performing an 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] At the positions of the first magnetic sensing unit 211 and the second magnetic sensing unit 212, I′1 and I 52 The magnetic fields generated by the axial magnetic field H are in opposite directions and offset and reduce each other, and the differential mode magnetic field H 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 I, thereby mainly playing a role in adjusting and increasing the current input range of the current detection 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 generates only the current to be measured 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

[0100] Optionally, the first magnetic sensing unit 211 and the second magnetic sensing unit 212 are two separately located giant magnetic impedance (GMI) units with a right-direction sensitivity direction. According to the above analysis, there is a difference between the magnetic fields generated by the stepped copper bar 1 at the position of the first magnetic sensing unit 211 and the position of the second magnetic sensing unit 212, and the current shunt copper bar 52 can only offset and reduce 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 magnetic 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 stepped copper bar.

[0102] In this embodiment, one current shunt copper bar is connected in series with the 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 the characteristics of adjustable common mode magnetic field operating point, applicability to various magnetic sensing units, adjustable sensitivity, input and output electrical isolation, strong common mode interference resistance ability, DC and AC current measurement ability, and large current measurement ability.

[0103] The above-mentioned several 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 magnetoresistance bridge arms, and the second magnetic sensing unit is composed of two magnetoresistance bridge arms. The magnetoresistance bridge arms are composed of one or more magnetoresistance sensing elements connected in series and parallel. The four magnetoresistance 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. Obviously, there are many other embodiments including copper bars for current shunting and are not limited to the above-mentioned exemplary embodiments.

[0104] Although there are many embodiments including the copper bar for current shunt, it can be understood that after introducing one or more copper bars for current shunt and adopting the series-parallel connection method, their analysis and calculation are almost the same as the above analysis process. In addition, no matter which case is adopted, for the current sensing device with stepped copper bar in which the copper bar for current shunt is introduced, 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 current sensing device with stepped copper bar can reach the maximum, that is, the differential mode magnetic field can be fully extended to the operating range of the magnetoresistance sensing element, so that the following equations (14) and (15) can be obtained.

[0105]

number

number

[0106] Furthermore, in an ideal situation, the magnetic field generated by the current ΔI1 in the upper rectangle at the position of the second magnetic sensing unit 42 is very small, k 22 = 0, which allows the above equation (14) to 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 is proportional to the measured current 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 are fully offset, limiting the operating range of the magnetoresistive sensing element to the differential mode magnetic field H DM to provide the maximum measurement current range.

[0109] Please note 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 embodiment described herein, and 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 embodiment, the present invention is not limited to the above embodiment only, and may include many other equivalent embodiments 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 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 with a stepped copper bar, characterized in that a measured current flows through a 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 measured current flowing through the stepped copper bar, and generate and output a differential voltage signal.

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 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 sensing device with stepped copper bar of claim 1, further comprising a mechanical support housing that encases, secures and supports said magnetic induction module and said 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 the magnetic field dynamic equilibrium 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 as claimed in 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 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 and 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 and a second step; 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, and the second magnetic sensing unit is located above the second step; A current detection device with a stepped copper bar, characterized in that a current to be measured flows through a 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, and 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 measured current input module, and generate a voltage signal that forms an output signal of the current detection device with a stepped copper bar.

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 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 sensing device with stepped copper bar as claimed in 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, the two 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 sensing device with stepped copper bar as claimed in claim 6, wherein the first magnetic sensing unit and the second magnetic sensing unit are located on the same chip or on 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 sensing device with stepped copper bar of claim 6, characterized in that 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 the differential mode magnetic field in opposite directions, when the 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.

11. The number of the current shunt copper bars is one or more; A current detection device with a stepped copper bar according to any one of claims 6 to 10, characterized in that 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, characterized in that, in the current detection device with stepped copper bars, the input range of the measured current 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 measured current of the current detection device with stepped copper bars is adjusted by setting the number of the current shunt copper bars.

Images