Gmr current sensor bus and gmr current sensor

Abstract

The application provides a busbar for GMR current sensor and a GMR current sensor. In the busbar, a notch part is formed in the busbar, so that the parts of the busbar on both sides of the notch part form a first current branch passage and a second current branch passage for current diversion. In the longitudinal section of the busbar, the width of the first current branch passage in the orthogonal direction perpendicular to the current flowing direction in the busbar is different from the width of the second current branch passage in the orthogonal direction. In this way, in the busbar for GMR current sensor according to the application, since it is not necessary to form a strip-shaped slit as in the prior art, the manufacturing cost of the busbar is reduced and the flexibility of the manufacturing structure is improved, which is beneficial to large-scale industrial production; and since two current branch passages with different widths are formed, the adverse effect of the skin effect of the current on the measurement result of the GMR current sensor can be effectively reduced.

Description

Technical Field

[0001] This invention relates to a technique for measuring current using giant magnetoresistive (GMR) technology, and more specifically to a busbar for a GMR current sensor and a GMR current sensor including the busbar. Background Technology

[0002] Compared with traditional Hall current sensors, GMR current sensors have advantages such as lower cost, higher sensitivity, smaller weight and installation space, lower noise and less susceptibility to temperature changes. Therefore, GMR current sensors have been increasingly widely used.

[0003] A GMR current sensor consists of a hollow busbar and a GMR chip. When the current to be sensed flows through the busbar, the magnitude of the current is determined by sensing the differential magnetic flux using a GMR bridge. However, when the current frequency is too high, the skin effect can cause significant errors in the GMR current sensor's measurement results. Studies have shown that when the current frequency is around 3000 Hz and the current magnitude is around 100 A, the measurement error caused by the skin effect can even reach approximately 5%.

[0004] Therefore, those skilled in the art can minimize the adverse effects of the skin effect of current on the measurement results of GMR current sensors by modifying the structure of the busbar. For example, in... Figure 1 In the GMR current sensor shown, two beams (current branch paths) 101 of equal width are formed on both sides of the notch 10h1 of the busbar 10, and the GMR chip 20 is located at the notch 10h1. A strip-shaped slit 10h2 (with a width of, for example, 0.5 mm) extending along the direction of current flow is formed within each beam 101. Although this GMR current sensor busbar 10 reduces the adverse effects of the skin effect on the measurement results of the GMR current sensor, the manufacturing cost of this busbar 10 structure is too high, which is not conducive to large-scale industrial production. Summary of the Invention

[0005] The present invention was made in response to the deficiencies of the prior art described above. One objective of the present invention is to provide a novel busbar for GMR current sensors that, compared to the busbars described in the background art, effectively reduces the adverse effects of the skin effect of current on the measurement results of the GMR current sensor while lowering manufacturing costs. Another objective of the present invention is to provide a GMR current sensor including this busbar.

[0006] To achieve the above-mentioned objectives, the present invention may employ the following technical solutions.

[0007] The present invention provides a busbar for a GMR current sensor, wherein the current to be sensed flows along a first direction in the busbar.

[0008] The busbar has a notch, such that the portions of the busbar on both sides of the notch form a first current branch path and a second current branch path for current diversion.

[0009] In the longitudinal section taken along the first direction of the busbar, the first width W1 of the first current branch path in the second direction orthogonal to the first direction is different from the second width W2 of the second current branch path in the second direction.

[0010] Preferably, in the longitudinal section of the busbar, the busbar has a rectangular shape and the notch has a rectangular shape, and the sides of the notch are parallel to the sides of the busbar.

[0011] More preferably, in the longitudinal section of the busbar, the first width W1, the second width W2, and the total width W of the busbar in the second direction satisfy: W1+W2≤0.5×W.

[0012] More preferably, in the longitudinal section of the busbar, the first width W1 and the second width W2 satisfy: W1≥2×W2.

[0013] The present invention also provides a GMR current sensor comprising the busbar described in any of the above technical solutions.

[0014] Preferably, the GMR current sensor further includes a GMR chip.

[0015] When viewed along a third direction orthogonal to the first and second directions, the GMR chip is located within the notch.

[0016] More preferably, when viewed along the third direction, the position of the GMR chip in the second direction is closer to the first current branch path relative to the second current branch path.

[0017] More preferably, the GMR chip is a chip packaged in a SiP package.

[0018] By adopting the above technical solution, the present invention provides a busbar for a GMR current sensor and a GMR current sensor including the busbar. In the busbar, a notch is formed, such that portions of the busbar on both sides of the notch form a first current branch path and a second current branch path for current shunting. In the longitudinal section of the busbar, the width of the first current branch path in an orthogonal direction orthogonal to the current flow direction in the busbar is different from the width of the second current branch path in that orthogonal direction.

[0019] Thus, in the busbar for the GMR current sensor according to the present invention, since it is not necessary to form a strip-shaped slit as in the prior art, the manufacturing cost of the busbar is reduced and the flexibility of the manufacturing structure is improved, which is beneficial to large-scale industrial production; moreover, since two current branch paths with different widths are formed, the adverse effects of the skin effect of the current on the measurement results of the GMR current sensor can be effectively reduced. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the structure of a prior art GMR current sensor, where the arrows indicate the direction of current flow in the busbar.

[0021] Figure 2 This is a schematic diagram of the structure of a GMR current sensor according to an embodiment of the present invention, where the arrows indicate the direction of current flow in the busbar.

[0022] Figure 3a This is a graph showing the relationship between the differential magnetic flux density generated by currents of different frequencies in the busbar of a prior art GMR current sensor and the position of the GMR chip, where the horizontal axis represents the position of the GMR chip relative to the busbar in the second direction (in mm), and the vertical axis represents the differential magnetic flux density (in mT). Figures 3b to 3d The following are examples of the methods used: Figure 2 The graphs show the relationship between the differential magnetic flux density generated by the current at different frequencies in the busbar of different examples of GMR current sensors and the position of the GMR chip, where the horizontal axis represents the position of the GMR chip relative to the busbar in the second direction (in mm), and the vertical axis represents the differential magnetic flux density (in mT).

[0023] Explanation of reference numerals in the attached figures

[0024] 10 busbars, 101 beams, 10h1 notch, 10h2 seam, 20GMR chip

[0025] 1 Busbar 11 First Current Branch Path 12 Second Current Branch Path 1h Notch 2GMR Chip

[0026] W1 is the first width, W2 is the second width, and W is the total width. Detailed Implementation

[0027] The specific embodiments of the present invention will be described below. In the present invention, "longitudinal section" refers to a busbar section orthogonal to the axis of the notch in the busbar, taken along the direction of current flow in the busbar.

[0028] like Figure 2 As shown, a GMR current sensor according to an embodiment of the present invention includes a busbar 1 and a GMR chip 2.

[0029] Specifically, in this embodiment, the longitudinal section of the busbar 1 has a rectangular shape, and the busbar 1 has a notch 1h, which also has a rectangular shape. The long side of the notch 1h is parallel to the long side of the longitudinal section of the busbar 1, and the short side of the notch 1h is parallel to the short side of the longitudinal section of the busbar 1.

[0030] In bus 1, the current to be sensed travels along the first direction ( Figure 2 The current flows through busbar 1 in an upward direction, and the portions of busbar 1 located on the left and right sides of the notch 1h form a first current branch path 11 and a second current branch path 12 for current diversion. Let the second direction be the direction orthogonal to the first direction in the longitudinal section of busbar 1. Then, when viewed along a third direction orthogonal to the first and second directions, the GMR chip 2 is located within the notch 1h. Furthermore, in this embodiment, the GMR chip 2 is a chip using a system-in-package (SIP) package.

[0031] In the longitudinal section of busbar 1, the first width W1 of the first current branch path 11 in the second direction is greater than the second width W2 of the second current branch path 12 in the second direction. This can effectively reduce the adverse effect of the skin effect of the current on the measurement results of the GMR current sensor.

[0032] Preferably, in the longitudinal section of busbar 1, the first width W1, the second width W2, and the total width W of busbar 1 in the second direction satisfy: W1+W2≤0.5×W; and / or the first width W1 and the second width W2 satisfy: W1≥2×W2. This can further effectively reduce the adverse effects of the skin effect of the current on the measurement results of the GMR current sensor.

[0033] To demonstrate that the bus structure of the GMR current sensor according to the present invention can effectively reduce the adverse effects of the skin effect of the current on the measurement results of the GMR current sensor, the following experiment was conducted.

[0034] In a comparative example of the busbar structure of a GMR current sensor employing existing technology, the first current branch path and the second current branch path are not configured as described above. Figure 1 The slit shown has a width of 5.5 mm for both the first and second current branch paths, and a total busbar width of 20 mm. The differential magnetic flux density is obtained by measuring the differential magnetic flux density of the busbar when currents of the same magnitude at frequencies of 10 Hz, 1000 Hz, 2000 Hz, and 3000 Hz pass through it using GMR chips positioned at different locations along the second direction. Figure 3a The graph shown. From Figure 3a It can be seen that, regardless of the location of the GMR chip, the differential magnetic flux density is always significantly affected by the frequency of the current. In other words, the measurement results of the existing GMR current sensor are always significantly affected by the skin effect of the current.

[0035] In one example of a busbar structure employing the GMR current sensor according to the present invention, the first width W1 of the first current branch path 11 is 8 mm, the second width W2 of the second current branch path is 3 mm, and the total width W of the busbar 1 is 20 mm. The differential magnetic flux density is obtained by measuring the differential magnetic flux density of the same magnitude of current passing through the busbar 1 at frequencies of 10 Hz, 1000 Hz, 2000 Hz, and 3000 Hz using GMR chips 2 positioned at different locations along the second direction. Figure 3b The graph shown. From Figure 3b As can be seen, compared with the above comparative example, the differential magnetic flux density measured by GMR chip 2 at the marked position within the rectangular box is less affected by the frequency of the current. In other words, the GMR current sensor according to this example can achieve the effect that the measurement result is less affected by the skin effect of the current.

[0036] In another example of the busbar structure employing the GMR current sensor according to the present invention, the first width W1 of the first current branch path 11 is 7 mm, the second width W2 of the second current branch path 12 is 2 mm, and the total width W of the busbar 1 is 20 mm. The differential magnetic flux density is obtained by measuring the differential magnetic flux density of the same magnitude of current passing through the busbar 1 at frequencies of 10 Hz, 1000 Hz, 2000 Hz, and 3000 Hz respectively, using GMR chips 2 positioned at different locations along the second direction. Figure 3c The graph shown. From Figure 3c As can be seen, the differential magnetic flux density measured by the GMR chip 2 at the marked position within the rectangular box is almost unaffected by the frequency of the current. In other words, the GMR current sensor according to this example can achieve the effect that the measurement results are almost unaffected by the skin effect of the current.

[0037] In another example of the busbar structure employing the GMR current sensor according to the present invention, the first width W1 of the first current branch path 11 is 6 mm, the second width W2 of the second current branch path 12 is 3 mm, and the total width W of the busbar 1 is 20 mm. The differential magnetic flux density is obtained by measuring the differential magnetic flux density of the same magnitude of current passing through the busbar 1 at frequencies of 10 Hz, 1000 Hz, 2000 Hz, and 3000 Hz using GMR chips 2 positioned at different locations along the second direction. Figure 3d The graph shown. From Figure 3d As can be seen, the differential magnetic flux density measured by the GMR chip 2 at the marked position within the rectangular box is almost unaffected by the frequency of the current. In other words, the GMR current sensor according to this example can achieve the effect that the measurement results are almost unaffected by the skin effect of the current.

[0038] The above experiments demonstrate that by employing the busbar 1 of the GMR current sensor according to the present invention, the adverse effects of the skin effect of the current on the measurement results of the GMR current sensor can be effectively reduced. Furthermore, since the busbar 1 of the GMR current sensor according to the present invention does not require the formation of a slot as seen in the busbar 10 of the prior art, costs are reduced, which is beneficial for large-scale industrial production.

[0039] The technical solution of the present invention has been described in detail above, and the following is a supplementary explanation.

[0040] i. Although the specific embodiments described above state that the first width W1 of the first current branch path 11 in the second direction orthogonal to the first direction is greater than the second width W2 of the second current branch path 12 in the second direction, the present invention is not limited thereto. The first width W1 of the first current branch path 11 in the second direction can be smaller than the second width W2 of the second current branch path 12 in the second direction. That is, it is sufficient that the first width W1 of the first current branch path 11 in the second direction is different from the second width W2 of the second current branch path 12 in the second direction.

[0041] ii. Figures 3b to 3d The further the horizontal axis extends to the right in the diagram, the closer the GMR chip 2 is to the first current branch path 11 in the second direction. Therefore, preferably, when viewed along the third direction, the position of the GMR chip 2 in the second direction is set to be closer to the first current branch path 11 than the second current branch path 12. In this way, the measurement results of the current flowing through the bus 1 by the GMR chip 2 at the above-mentioned position are less affected or essentially unaffected by the skin effect of the current.

[0042] iii. Through, for example Figure 3c and Figure 3dThe curves in the graph and Figure 3b As can be seen from the curves, W1≥2×W2 can significantly reduce the influence of the skin effect of the current on the measurement results of the current flowing through the bus 1 by the GMR chip 2.

Claims

1. A busbar for a GMR current sensor, in which the current to be sensed flows along a first direction, The busbar (1) has a notch (1h) such that the portions of the busbar (1) located on both sides of the notch (1h) form a first current branch path (11) and a second current branch path (12) for the current to be shunted. In the longitudinal section of the busbar (1) taken along the first direction, the first width W1 of the first current branch path (11) in the second direction orthogonal to the first direction is different from the second width W2 of the second current branch path (12) in the second direction. in, In the longitudinal section of the busbar (1), the first width W1, the second width W2 and the total width W of the busbar (1) in the second direction satisfy: W1+W2≤0.5×W.

2. The busbar according to claim 1, characterized in that, In the longitudinal section of the busbar (1), the busbar (1) has a rectangular shape and the notch (1h) has a rectangular shape, and the sides of the notch (1h) are parallel to the sides of the busbar (1).

3. The busbar according to claim 1 or 2, characterized in that, In the longitudinal section of the busbar (1), the first width W1 and the second width W2 satisfy: W1≥2×W2.

4. A GMR current sensor comprising the bus (1) according to any one of claims 1 to 3.

5. The GMR current sensor according to claim 4, characterized in that, The GMR current sensor also includes a GMR chip (2). When viewed along a third direction orthogonal to the first and second directions, the GMR chip (2) is located within the notch (1h).

6. The GMR current sensor according to claim 5, characterized in that, When viewed along the third direction, the position of the GMR chip (2) in the second direction is closer to the first current branch path (11) relative to the second current branch path (12).

7. The GMR current sensor according to claim 5, characterized in that, The GMR chip (2) is a chip packaged in SIP.

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