A special-shaped busbar current sensor and current testing method thereof
By designing the step structure of the concave cutout groove and differential magnetic sensitive chip of the special-shaped busbar current sensor in the busbar current sensor, the problem of insufficient bandwidth and current capacity of the magnetic core-free current sensor in the new energy system is solved, and the problem of insufficient bandwidth and current capacity of the magnetic core-free current sensor in the new energy system is realized. More efficient current sensing.
Patent Information
- Application Number
- CN202411349801.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2044-09-26
AI Technical Summary
Existing magnetic core-free current sensors are susceptible to external interference in new energy systems, have low signal-to-noise ratios, and large position errors of sensitive components, resulting in reduced bandwidth and weak current capacity, making it difficult to effectively detect busbar current.
A special-shaped busbar current sensor is designed, and a differential magnetic sensitive chip is used to form a step structure with the concave cut groove of the busbar body. The current detection capability is enhanced through the design of the concave cut groove, offset the environmental magnetic field to improve detection accuracy.
The bandwidth and current throughput of current detection are enhanced, position error is reduced, and the accuracy of current detection and anti-interference ability are improved.
Smart Images
Figure CN118858737B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of current detection sensors, and in particular to a special-shaped busbar current sensor and a current testing method for the special-shaped busbar current sensor. Background Art
[0002] In new energy electric drive systems, current sensors are required to determine the AC phase current transmitted from the inverter power module to the motor.
[0003] Conventional current sensors based on open-loop magnetic cores are usually used to achieve AC current detection. Conventional open-loop current sensors place a magnetic core with an open air gap around the busbar to concentrate the magnetic field generated by the busbar current into the air gap. The magnetic sensitive chip at the air gap can sense the magnetic field proportional to the busbar, thereby achieving busbar current measurement. However, due to the inherent properties of the magnetic core, including nonlinearity, saturation, hysteresis, remanence, and temperature-dependent magnetic permeability, the use of current sensors based on open-loop magnetic cores has many disadvantages.
[0004] With the development of new energy systems, system costs are reduced, power is increased, and volume is reduced. These trends put forward corresponding requirements for sensors, and coreless current sensors came into being. For example, the technical solution described in CN 117805467 A, a coreless current sensor and its application. Compared with open-loop magnetic sensors, coreless sensors have no core, which reduces the core cost and module volume. But it also brings disadvantages: 1. Due to the lack of a magnetic core, the measured magnetic field is weakened, the coreless current sensor is easily interfered by the outside world, and the signal-to-noise ratio is reduced. 2. The lack of a magnetic core also makes the magnetic field at the position of the sensitive element uneven, and the position error has a great impact on the output. 3. The lack of a magnetic core weakens the measured magnetic field, so the sensitive element is close to the busbar, and the high and low frequency distribution of the busbar current will have a greater impact, thereby affecting the bandwidth.
[0005] Therefore, in view of the shortcomings of the prior art, it is necessary to provide a special-shaped busbar current sensor and a current testing method for the special-shaped busbar current sensor to overcome the shortcomings of the prior art. Summary of the invention
[0006] One of the purposes of the present invention is to avoid the deficiencies of the prior art and provide a special-shaped busbar current sensor, which can solve the characteristics of reduced bandwidth, weakened current carrying capacity and large position error, and enhance the current detection capability.
[0007] The above-mentioned purpose of the present invention is achieved through the following technical means.
[0008] A special-shaped busbar current sensor comprises a busbar body and a differential magnetic sensitive chip, wherein the busbar body is provided with a concave cutout groove for installing the differential magnetic sensitive chip, wherein the concave cutout groove comprises a first inner cutout penetrating the busbar body and a second inner cutout penetrating the first inner cutout; the width direction of the busbar body is perpendicular to the flow direction (current flow direction) of the busbar body, and the second inner cutout thins the busbar body along the width direction of the busbar body; the width W1 of the busbar body is greater than the width W2 of the second inner cutout, and the width W2 of the second inner cutout is greater than the width W3 of the first inner cutout; the concave cutout groove forms a stepped structure corresponding to the differential magnetic sensitive chip.
[0009] Preferably, there are two second inner cutouts, which are respectively located at two through ends of the first inner cutout; and the thinning thickness of the busbar body by the two second inner cutouts is the same.
[0010] Furthermore, the two side surfaces of the concave cutout groove corresponding to the differential magnetic sensitive chip form a stepped structure; further, the first inner cutout and the second inner cutout are arranged symmetrically on the left and right, which is more conducive to generating magnetic fields of equal magnitude and opposite directions at the two through ends of the first inner cutout after current is passed through the busbar body.
[0011] Furthermore, the width W1 of the busbar body is 15mm≤W1≤20mm; the width W2 of the second inner cut is 6mm≤W2≤8mm; the width W3 of the first inner cut is 2mm≤W3≤5mm. The thickness th1 of the busbar body is 3mm≤th1≤5mm; the thickness th2 of the busbar body after the second inner cut is thinned is 1mm≤th2≤3mm.
[0012] Preferably, the width W1 of the busbar body is 18 mm, the width W2 of the second inner cut is 6 mm, and the width W3 of the first inner cut is 2 mm; the thickness th1 of the busbar body is 3 mm, and the thickness th2 of the busbar body where the second inner cut thins the busbar body is 1.5 mm.
[0013] The first inner cutout and the second inner cutout have the same cutout length along the flow direction of the busbar body.
[0014] Furthermore, the differential magnetic sensitive chip includes two detection ends, the two detection ends respectively correspond to the second inner cutouts of the two through ends of the first inner cutout, and the distance L between the two detection ends is 2mm≤L≤3mm. An insulating film is also provided, the insulating film is coated on the busbar body, and the insulating coating is used to solve the voltage resistance problem of the differential magnetic sensitive chip.
[0015] Another object of the present invention is to provide a current testing method of a special-shaped busbar current sensor using the special-shaped busbar current sensor technology described above. The current testing method of the special-shaped busbar current sensor measures the magnetic field of the concave cutout groove with a stepped structure of the busbar body through a differential magnetic sensitive chip, thereby measuring the busbar body current.
[0016] Specifically, it includes step s1, when current flows through the busbar body, magnetic fields of equal magnitude and opposite directions are generated at the two through ends of the first inner cutout, which are respectively denoted as -H and H; step s2, obtaining the magnetic fields of the two through ends of the first inner cutout of the busbar body through a differential magnetic sensitive chip, which are respectively denoted as H1 and H2, and the environmental magnetic field is denoted as He, wherein H1=H+He, H2=-H+He; step s3, magnetic field data processing, after H1-H2=2H offsets the environmental magnetic field He, the magnetic field H generated by the current flowing through the busbar body can be obtained; step s4, according to the measured magnetic field H generated by the current flowing through the busbar body, the busbar body current is obtained.
[0017] The special-shaped busbar current sensor of the present invention is innovatively designed for the inner concave cutout groove of the busbar body. A second inner cutout for thinning the busbar body is arranged at the end of the first inner cutout that penetrates the busbar body along the width direction of the busbar body and perpendicular to the current flow direction of the busbar body, so that the inner concave cutout groove forms a stepped structure corresponding to the differential magnetic sensitive chip. In the prior art, when the current of the busbar body flows, since the magnetic sensitive chip is close to the busbar body, the high and low frequencies of the current distribution of the busbar body have a greater impact on the magnetic field detection of the magnetic sensitive chip, thereby affecting the bandwidth; the present invention forms a stepped structure corresponding to the magnetic sensitive chip in the inner concave cutout groove, which can adapt to the impact of the high and low frequencies of the current distribution when the current of the busbar body flows, and solve the problem of reduced bandwidth. The present invention also has better flow capacity and smaller position error to enhance the effect of current detection. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The present invention is further described with reference to the accompanying drawings, but the contents in the accompanying drawings do not constitute any limitation to the present invention.
[0019] Figure 1 It is a schematic diagram of the structure of the present invention.
[0020] Figure 2 It is a schematic diagram of the cross-sectional structure of the present invention.
[0021] Figure 3 It is a schematic diagram of the cross-sectional structure of the busbar body of the present invention.
[0022] Figure 4 This is a diagram of the position error when the width w3 of the concave cut groove of the present invention changes by 100 um in the y direction when the width w3 is 2 mm and 5 mm respectively.
[0023] Figure 5 It is a diagram of the position error when the width w3 of the concave cut groove of the present invention changes by 100 um in the x direction when the cut width w3 is 2 mm and 5 mm respectively.
[0024] Figure 6 It is a schematic diagram of the magnetic field distribution structure of the cross section of the busbar body at the indentation of the indentation groove of the present invention.
[0025] Figure 7 It is a schematic diagram of the structure of the comparison busbar of the present invention.
[0026] Figure 8 It is a diagram comparing the magnetic simulation magnetic field at different frequencies at the busbar differential sensitive element.
[0027] Fig. 9 It is a diagram of the magnetic simulation magnetic field at different frequencies at the differential sensitive element of the busbar body of the present invention.
[0028] Fig.10 It is a diagram comparing the current density of the busbar cutout cross section.
[0029] Fig.11 It is a diagram of the current density of the cross section of the busbar body of the present invention.
[0030] Fig.12 yes Figure 7 The comparison busbars shown are similar to those shown in Figure 1 The busbar shown in the figure was used for the experiment, and the output sensitivity attenuation is shown in the figure.
[0031] Fig.13 It is a structural schematic diagram of the differential sensitive element spacing L of the present invention.
[0032] exist Figures 1 to 13 Including:
[0033] The busbar body 100 , the inner concave notch groove 200 , the first inner notch 201 , the second inner notch 202 ; and the differential magnetic sensitive chip 300 . DETAILED DESCRIPTION
[0034] The present invention is further described in conjunction with the following examples.
[0035] Example 1
[0036] A special-shaped busbar current sensor, such as Figure 1 and Figure 2As shown, it includes a busbar body 100 and a differential magnetic sensitive chip 300, wherein the busbar body 100 is provided with an inner recessed notch 200 for installing the differential magnetic sensitive chip 300. The inner recessed notch 200 includes a first inner notch 201 penetrating the busbar body 100 and a second inner notch 202 penetrating the first inner notch 201.
[0037] The width direction of the busbar body 100 is perpendicular to the flow direction (current flow direction) of the busbar body 100 , and the second inner cutout 202 performs a thinning process on the busbar body 100 along the width direction of the busbar body 100 .
[0038] like Figure 1 As shown, the x direction is defined as the width direction of the busbar body 100 , the y direction is defined as the length direction of the busbar body 100 and the current flow direction of the busbar body 100 , and the z direction is defined as the thickness direction of the busbar body 100 .
[0039] The width W1 of the busbar body 100 is greater than the width W2 of the second inner cutout 202 , and the width W2 of the second inner cutout 202 is greater than the width W3 of the first inner cutout 201 ; the inner concave cutout groove 200 forms a stepped structure corresponding to the differential magnetic sensitive chip 300 .
[0040] As a preferred example, Figure 2 and Figure 3 As shown, there are two second inner cutouts 202 , which are respectively located at two through ends of the first inner cutout 201 ; the thinning thickness of the busbar body 100 by the two second inner cutouts 202 is the same.
[0041] In this embodiment, the busbar body 100 is thinned from its upper and lower surfaces, and then the second inner cutouts 202 are respectively formed at the upper and lower through ends of the first inner cutout 201 of the busbar body 100. The thinning thickness of the busbar body 100 by the two second inner cutouts 202 is the same, that is, the two second inner cutouts 202 are symmetrically arranged with respect to the first inner cutout 100, which is more conducive to solving the problem that the different high and low frequencies of the current distribution of the busbar body 100 have a greater impact on the bandwidth.
[0042] like Figure 3As shown, the width W1 of the busbar body 100 is 15mm≤W1≤20mm; the width W2 of the second inner cutout 202 is 6mm≤W2≤8mm; the width W3 of the first inner cutout 201 is 2mm≤W3≤5mm. The cutout lengths of the first inner cutout 201 and the second inner cutout 202 along the flow direction of the busbar body 100 are the same. The thickness th1 of the busbar body 100 is 3mm≤th1≤5mm; the thickness th2 of the busbar body 100 after the second inner cutout 202 thins the busbar body 100 is 1mm≤th2≤3mm.
[0043] Specifically, the width W1 of the busbar body is 18 mm, the width W2 of the second inner cut is 6 mm, and the width W3 of the first inner cut is 2 mm; the thickness th1 of the busbar body is 3 mm, and the thickness th2 of the busbar body where the second inner cut thins the busbar body is 1.5 mm.
[0044] Furthermore, the two side surfaces of the concave cutout groove 200 corresponding to the differential magnetic sensitive chip 300 form a stepped structure; further, the first inner cutout 201 and the second inner cutout 202 are arranged symmetrically on the left and right, which is more conducive to generating magnetic fields of equal magnitude and opposite directions at the two through ends of the first inner cutout 201 after current is passed through the busbar body 100.
[0045] like Fig.13 As shown, the differential magnetic sensitive chip 300 includes two detection ends, which respectively correspond to the second inner cutouts 202 of the two through ends of the first inner cutout 201, and the distance L between the two detection ends is 2mm≤L≤3mm, and is preferably 2.5mm in this embodiment.
[0046] In this embodiment, if Figure 1 As shown, the current direction of the busbar body 100 is taken as the z-axis, then Figure 2 As shown, the busbar body 100 with current flowing through it generates magnetic fields H and -H of equal magnitude and opposite directions at the upper and lower detection ends of the differential magnetic sensitive chip 300. If the ambient magnetic field is He, the magnetic fields H1 and H2 measured by the two sensitive elements of the differential magnetic sensitive chip 300 are respectively: H1=H+He; H2=-H+He.
[0047] The measurement result of the differential sensitive element is processed as follows: H1-H2=2H, so that the magnetic field He generated by the external interference can be offset, and the magnetic field generated by the busbar body 100 can be obtained, thereby knowing the current of the busbar body 100.
[0048] It should be further explained that, considering the influence of installation tolerance, vibration, high and low temperature environment factors, the position of the differential magnetic sensitive chip 300 will change during long-term operation. Compared with the z direction, the position error in the x and y directions is larger. Further, the position error in the x and y directions is analyzed.
[0049] Figure 4 When the first inner incision width w3 is 2 mm and 5 mm respectively, and the y coordinates of the sampling points are 1 mm, 1.25 mm, 1.5 mm, and 2 mm respectively, the position error when the y direction changes by 100 um.
[0050] Figure 5 The first inner cut width w3 is 2 mm and 5 mm respectively, and the position error when the x coordinate of the sampling point is 0 mm at the center and the x direction changes by 100 um.
[0051] pass Figure 4 and Figure 5 It can be seen that the position error in the x direction is much smaller than the position error in the y direction, so the influence of the position error in the y direction is mainly considered. The smaller the cutout, the smaller the position error in the y direction; but the smaller the cutout, the worse the isolation withstand voltage of the differential magnetic sensitive chip 300.
[0052] Figure 6 The magnetic field distribution of the cross section of the busbar body 100, the closer to the center, the more drastic the magnetic field change, the smaller the measured magnetic field, the larger the position error, that is, it is hoped that the distance between the sensitive elements at the two detection ends of the differential magnetic sensitive chip 300 is slightly far, but the farther the distance between the differential sensitive elements is, the greater the difference in the magnetic field generated by external interference at the two sensitive elements, and the worse the external interference offset effect.
[0053] Therefore, after comprehensive consideration, in this embodiment, the distance L between the two detection ends of the differential magnetic sensitive chip 300 is 2.5 mm, but in practice the specific distance can be adjusted according to actual needs.
[0054] like Figure 7 As shown, a comparative example is set. In this comparative example, the concave cutout groove 200 is directly in the busbar body 100 to perform a thinning process on the entire cross section. The comparative busbar in which the concave cutout groove 200 is directly in the busbar body 100 to perform a thinning process on the entire cross section is shown in FIG. Figure 7 shown.
[0055] At the same time, Figure 7 The busbar ratio shown is similar to Figure 1 The busbar body 100 shown in the figure is subjected to bandwidth and current carrying capacity analysis. The two busbars are subjected to magnetic field simulation with different frequencies and amplitude of 500A. The simulated magnetic field at the differential magnetic sensitive chip 300 is as follows: Figure 8 , Fig. 9 As shown. Among them, the center of the incision is the origin coordinate, that is, Figure 8 , Fig. 9 is the magnetic field at the coordinates (0mm, 1.25mm, 0mm).
[0056] When the frequency is 5kHz and the current reaches a peak value of 500A, Figure 7 The comparison busbars shown are similar to those shown in Figure 1 The current density of the cross section of the busbar body 100 is shown as Fig.10 , Fig.11 As shown, when the frequency is high, the current density is not uniform, and the magnetic field at the differential magnetic sensitive chip 300 is different from that at low frequency. Figure 7 Compared with the comparative busbar shown, the busbar body 100 in the present application has significantly less uneven current density, so the magnetic field variation at different frequencies is greatly reduced. In addition, the busbar body 100 in the present application has a larger cross-sectional area and a greater current carrying capacity.
[0057] Using a chip with a bandwidth of 250kHz, Figure 7 The comparison busbars shown are similar to those shown in Figure 1 The output sensitivity is reduced as shown in the experiment. Fig.12 shown.
[0058] In summary, the inwardly recessed cutout groove 200 of the busbar body 100 of the present application adopts a stepped structure, which solves the problems of bandwidth and flow capacity at the same time.
[0059] Example 2
[0060] A special-shaped busbar current sensor, the other structures of which are the same as those of Example 1, except that the special-shaped busbar current sensor is also provided with an insulating film covering the busbar body 100. The insulating film can improve the withstand voltage and reduce the defect of position error.
[0061] Example 3
[0062] A current testing method for a special-shaped busbar current sensor, the other structure of which is to use a special-shaped busbar current sensor as recorded in any one of the above-mentioned embodiments 1-2, the difference being that the current testing method for the special-shaped busbar current sensor measures the magnetic field of the concave cutout groove with a stepped structure of the busbar body through a differential magnetic sensitive chip, and then measures the busbar body current.
[0063] Specifically, the method comprises step s1, wherein current flows through the busbar body 100, and magnetic fields of equal magnitude and opposite directions are generated at two through ends of the first inner cutout 201, which are respectively denoted as -H and H.
[0064] Step s2, obtaining the magnetic fields of the two through ends of the first inner cutout 201 of the busbar body 100 through the differential magnetic sensitive chip 300, which are respectively denoted as H1 and H2, and the ambient magnetic field is denoted as He, wherein H1=H+He, H2=-H+He.
[0065] Step s3, magnetic field data processing, after the environmental magnetic field He is offset by H1-H2=2H, the magnetic field H generated by the current flowing through the busbar body 100 can be obtained.
[0066] Step s4, obtaining the current of the busbar body 100 according to the measured magnetic field H generated by the current flowing through the busbar body 100.
[0067] The current testing method of the special-shaped busbar current sensor can improve the external interference offset effect during current detection and enhance the accuracy of current detection.
[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.
Claims
1. A special-shaped busbar current sensor, comprising a busbar body and a differential magnetic sensitive chip, wherein the busbar body is provided with an inner concave cutout groove for installing the differential magnetic sensitive chip, characterized in that: The concave cutout groove includes a first inner cutout penetrating the busbar body and a second inner cutout penetrating the first inner cutout; the width direction of the busbar body is perpendicular to the flow direction of the busbar body, and the second inner cutout performs a thinning process on the busbar body along the width direction of the busbar body; The width W1 of the busbar body is greater than the width W2 of the second inner cutout, and the width W2 of the second inner cutout is greater than the width W3 of the first inner cutout; the inner concave cutout groove forms a stepped structure corresponding to the differential magnetic sensitive chip; There are two second inner cutouts, which are respectively located at two through-ends of the first inner cutout; the two second inner cutouts have the same thinning thickness for the busbar body; The two sides of the concave cutout groove corresponding to the differential magnetic sensitive chip both form a step structure; The first inner cutout and the second inner cutout have the same cutout length along the flow direction of the busbar body.
2. The special-shaped busbar current sensor according to any one of claim 1, characterized in that: The width W1 of the busbar body is 15mm≤W1≤20mm; the width W2 of the second inner incision is 6mm≤W2≤8mm; the width W3 of the first inner incision is 2mm≤W3≤5mm; the thickness th1 of the busbar body is 3mm≤th1≤5mm; the thickness th2 of the busbar body after the busbar body is thinned by the second inner incision is 1mm≤th2≤3mm.
3. The special-shaped busbar current sensor according to claim 2, characterized in that: The width W1 of the busbar body is 18 mm, the width W2 of the second inner cut is 6 mm, and the width W3 of the first inner cut is 2 mm; the thickness th1 of the busbar body is 3 mm, and the thickness th2 of the busbar body where the second inner cut thins the busbar body is 1.5 mm.
4. The special-shaped busbar current sensor according to claim 1, characterized in that: The differential magnetic sensitive chip comprises two detection ends, the two detection ends respectively correspond to the second inner cutouts of two through ends of the first inner cutout, and the distance L between the two detection ends is 2mm≤L≤3mm.
5. The special-shaped busbar current sensor according to claim 4, characterized in that: An insulating film is also provided, and the insulating film is coated on the busbar body.
6. A current testing method for a special-shaped busbar current sensor, characterized in that: By using the special-shaped busbar current sensor according to any one of claims 1 to 5, the magnetic field of the recessed cutout groove with a stepped structure of the busbar body is measured through a differential magnetic sensitive chip, thereby measuring the busbar body current.
7. The current testing method of the special-shaped busbar current sensor according to claim 6 is characterized in that: Step s1, current flows through the busbar body, and magnetic fields of equal magnitude and opposite directions are generated at two through ends of the first inner cutout, which are respectively denoted as -H and H; Step s2, obtaining the magnetic fields of the two through ends of the first inner cutout of the busbar body through a differential magnetic sensitive chip, which are respectively denoted as H1 and H2, and the ambient magnetic field is denoted as He, where H1=H+He, H2=-H+He; Step s3, magnetic field data processing, after the ambient magnetic field He is offset by H1-H2=2H, the magnetic field H generated by the current flowing through the busbar body can be obtained; Step s4, obtaining the busbar body current according to the measured magnetic field H generated by the current flowing through the busbar body.