A shunt resistor and current sensor

Abstract

The application provides a shunt resistor and a current sensor, wherein the shunt resistor is provided with a plurality of voltage sampling nodes which are spaced apart and arranged at two ends of a resistance element of the shunt resistor, and each voltage sampling node at the two ends corresponds to one of the plurality of current sampling paths, and each voltage sampling node is spaced apart and easy to be drawn out. The shunt resistor and the current sensor provided by the application have a plurality of current sampling paths for current detection of the resistance element, and the voltage of the plurality of current sampling paths is easy to be processed by averaging. When the bolt installation torque of the shunt resistor deviates from the preset value, the increase and decrease of the detection voltage of each current sampling path can be offset to a certain extent, the deviation between the actual voltage detection value and the ideal voltage detection value is reduced, the deviation between the current detection value corresponding to the voltage detection value is further reduced, and the current detection precision is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical sensor, in particular to a shunt resistor and a current sensor. BACKGROUND

[0002] At present, the current sensor mainly includes a Hall current sensor and a shunt resistor current sensor.

[0003] The Hall current sensor is a non-contact measurement, which indirectly measures the current size in the wire by measuring the magnetic field strength near the current, and can measure a larger current value, but the measurement precision is low and the temperature drift is large.

[0004] The shunt resistor current sensor is connected in series in the loop, and the current size in the wire is indirectly measured by measuring the voltage across the shunt resistor. In the shunt resistor current sensor, the shunt resistor includes a resistor element with a preset resistance value, and terminals arranged at both ends of the resistor element. Assembly holes are arranged on the terminals to press and fix the shunt resistor as a whole to the printed circuit board by bolts passing through the assembly holes. A voltage sampling node is arranged at each end of the resistor element, and the current information flowing through the resistor element is obtained through the voltage information of the voltage sampling node.

[0005] Among them, the impedance characteristic of the resistor element in the shunt resistor will be affected by the degree of bolt fastening. If the installation torque of each bolt does not meet the preset, or the bolt torque is reduced due to vibration, the impedance distribution inside the resistor element is changed, thereby changing the current density between the preset voltage sampling nodes, causing the deviation of the current flowing through the voltage sampling nodes, and thus causing the deviation of the final measurement. SUMMARY

[0006] Therefore, the purpose of the present application is to provide a shunt resistor and a current sensor to reduce the influence of the installation torque of the bolt on the measurement and improve the measurement reliability.

[0007] In one aspect, the present application provides a shunt resistor, which includes a longitudinally distributed resistor element and two terminals, wherein,

[0008] The terminals are extended from both ends of the resistor element, and at least two assembly holes are arranged in each terminal in the transverse direction.

[0009] The first end of the resistor element is provided with at least two first voltage sampling nodes which are spaced apart, and the second end is provided with at least two second voltage sampling nodes which are spaced apart. The number of the first voltage sampling nodes and the second voltage sampling nodes is equal, and they are arranged symmetrically with respect to the resistor element to form at least two current detection paths in the resistor element.

[0010] Optionally, the first voltage sampling nodes are uniformly spaced apart in the transverse direction.

[0011] Optionally, the mounting holes on the two terminals are symmetrically arranged with respect to the resistance element, two mounting holes are arranged on each of the terminals, and the first voltage sampling nodes are provided with four.

[0012] According to another aspect of the present application, a current sensor is provided, comprising a shunt resistor and a subtraction operation circuit arranged on a printed circuit board, wherein,

[0013] The shunt resistor comprises a resistance element longitudinally distributed and two terminals extended from two ends of the resistance element, at least two mounting holes are arranged transversely in each of the terminals, and the shunt resistor is fixed to the printed circuit board through bolts and the terminals;

[0014] At least two first voltage sampling nodes are arranged at intervals at a first end of the resistance element, at least two second voltage sampling nodes are arranged at intervals at a second end of the resistance element, the number of the first voltage sampling nodes and the second voltage sampling nodes is equal and they are symmetrically arranged with respect to the resistance element to form at least two current detection paths in the resistance element;

[0015] The first voltage sampling nodes are connected in parallel to a first input end of the subtraction operation circuit, and the second voltage sampling nodes are connected in parallel to a second input end of the subtraction operation circuit;

[0016] The current sensor provides a first current sensing signal representing the size of the current flowing through the shunt resistor at an output end of the subtraction operation circuit.

[0017] Optionally, an analog-to-digital converter is further included, an input end of the analog-to-digital converter is connected to an output end of the subtraction operation circuit, and the current sensor provides a second current sensing signal representing the size of the current flowing through the shunt resistor at an output end of the analog-to-digital converter.

[0018] Optionally, the subtraction operation circuit comprises an operational amplifier, a first resistor, a second resistor, and a plurality of access resistors, wherein,

[0019] The first resistor is connected between a negative input end and an output end of the operational amplifier;

[0020] The second resistor is connected between a positive input end and a ground of the operational amplifier;

[0021] The first voltage sampling nodes are respectively connected to the negative input end of the operational amplifier through one of the access resistors;

[0022] The second voltage sampling nodes are respectively connected to the positive input end of the operational amplifier through one of the access resistors.

[0023] The access resistors have the same resistance.

[0024] Optionally, the first voltage sampling nodes are uniformly spaced in the transverse direction.

[0025] Optionally, the mounting holes on the two terminals are symmetrically arranged with respect to the resistance element, two mounting holes are arranged on each terminal, and the first voltage sampling nodes are four in number.

[0026] The shunt resistor provided by the present application is configured with four or more mounting holes, and at least two first voltage sampling nodes and at least two second voltage sampling nodes are arranged at both ends of the resistance element, so as to form two or more current sampling paths in the resistance element. When the uniformity of the internal resistance distribution of the resistance element is changed due to the deviation of the bolt installation torque, the distribution density of the total current on different current paths is shifted, the current size on each current path is changed, or increased or decreased, and the voltage at both ends of each current detection path is increased or decreased. The shunt resistor of the present application independently sets the voltage sampling nodes of multiple current sampling paths, can average the sampling voltage on each current detection path, and can offset the current increase and decrease on each current path to a certain extent, so that the deviation of the current detection value after the averaging processing from the ideal value is reduced, and the accuracy of current detection is improved.

[0027] The current sensor provided by the present application is provided with the shunt resistor provided by the present application and a subtraction operation circuit on a printed circuit board. The voltage sampling nodes at both ends of the resistance element of the shunt resistor are connected in parallel to two input ends of the subtraction operation circuit, respectively. The output signal of the subtraction operation circuit is the average value of the voltage on each current detection path of the resistance element. The current increase and decrease on different current detection paths can be offset to a certain extent, the influence of the current density deviation caused by the deviation of the installation torque of the bolt on the accuracy of current detection is reduced, and the reliability of current detection is improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a structural schematic diagram of a shunt resistor in an embodiment of the present application;

[0029] Figure 2 FIG. 2 is a partial structural schematic diagram of a current sensor in an embodiment of the present application.

[0030] Main element symbol explanation: resistance element 10, terminal 20, lead-out area 30, mounting hole 21, first voltage sampling node 31, second voltage sampling node 32, subtraction operation circuit 01, operational amplifier U1, first resistor R1, second resistor R2, access resistor R3, analog-to-digital converter 02.

[0031] The following detailed description will further explain the present application with reference to the above mentioned drawings. DETAILED DESCRIPTION

[0032] For the purpose of promoting an understanding of the present application, the present application will be described with reference to the drawings. The present application is illustrated by a number of embodiments. However, the present application can be realized in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. It will be apparent that the scope of the present application is not limited to the embodiments set forth herein.

[0033] It should be noted that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can also be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] Referring to FIG. 1, a shunt resistor according to an embodiment of the present application is shown, which is provided with a resistance element 10 having a set resistance value, two terminals 20 are provided at both ends of the resistance element 10 in a longitudinal direction, the terminals 20 are fixedly connected to the resistance element 10, and assembly holes 21 are provided on the terminals 20 to fix the terminals 20 to a printed circuit board by means of bolts, thereby fixing the resistance element 10. Figure 1 A plurality of first voltage sampling nodes 31 and a plurality of second voltage sampling nodes 32 are provided at both ends of the resistance element 10, and an extraction area 30 is provided, the plurality of first voltage sampling nodes 31 and the plurality of second voltage sampling nodes 32 are arranged at the ends of the resistance element 10, and are extracted by the extraction area 30 to obtain the potential difference between both ends of the resistance element 10, and the current flowing through the resistance element 10 can be obtained according to the set resistance value of the resistance element 10 and Ohm's law.

[0036]

[0037] ​In the embodiment, two assembly holes 21 are arranged on each terminal 20 in the transverse direction, and the assembly holes 21 at both ends of the resistance element 10 are symmetrically arranged relative to the resistance element 10, so that the stress of the resistance element 10 is uniform when the bolt installation torque received by each assembly hole 21 is the same, and the internal impedance of the resistance element 10 is uniformly distributed in the transverse and longitudinal directions, and the voltage on each current detection path can accurately represent the current flowing through the resistance element 10.

[0038] In the embodiment, four first voltage sampling nodes 31 and four second voltage sampling nodes 32 are symmetrically arranged relative to the resistance element 10, so that the first voltage sampling nodes 31 and the second voltage sampling nodes 32 are collinear in the longitudinal direction, and a current detection path is formed between a pair of nodes corresponding to the first voltage sampling nodes 31 and the second voltage sampling nodes 32, which is parallel to the standard current path (the overall input and output path of the shunt resistor), thereby ensuring the correspondence of the voltages collected by the first voltage sampling nodes 31 and the second voltage sampling nodes 32.

[0039] When the bolt installation torque received by each assembly hole 21 is the same, the current in the resistance element 10 is uniformly distributed, and the voltage difference signal detected on each current detection path can accurately represent the current flowing through the resistance element 10.

[0040] Each node of the first voltage sampling nodes 31 and the second voltage sampling nodes 32 is separately led out, so as to obtain the voltage on each current sampling path and the current on each current sampling path.

[0041] When the bolt installation torque corresponding to each assembly hole deviates from the preset value, the internal impedance distribution of the resistance element 10 changes, which can cause the current on each current sampling path to deviate, while the total current remains unchanged. The current density is transferred, so that the current on part of the current sampling paths is smaller than the ideal value, and the current on part of the current sampling paths is larger than the ideal value. The potential difference between the voltage sampling nodes corresponding to the smaller and larger ideal values is averaged and balanced, and the potential difference after the average and balance is consistent with the ideal value, which can effectively reduce the influence of the deviation of the bolt installation torque from the preset value and improve the reliability of the current detection.

[0042] The embodiment corresponds to a shunt resistor with four assembly holes, and four groups of voltage sampling nodes are arranged. The first voltage sampling nodes 31 and the second voltage sampling nodes 32 are one-to-one aligned and matched in the longitudinal direction and uniformly spaced in the transverse direction. In an optional embodiment, at least two groups of voltage sampling nodes are arranged, and the specific number can be selected according to actual needs, production limitations, and other factors.

[0043] The input end and the output end of the shunt resistor are, for example, two lead-out areas 30 or two terminals 20, and the two ends of the resistor element correspond to the input end and the output end in parallel, thereby ensuring the symmetry of the input current.

[0044] Please refer to Figure 2 , which is a partial structure diagram of the current sensor according to the embodiment of the application. The current sensor according to the embodiment is provided with the shunt resistor, the subtraction operation circuit 01 and the analog-to-digital converter 02 on the printed circuit board.

[0045] The sub-nodes of the first voltage sampling node 31 are connected to the first input end of the subtraction operation circuit 01 in parallel, and the sub-nodes of the second voltage sampling node 32 are connected to the second input end of the subtraction operation circuit 01 in parallel. Overall, the subtraction operation processing of the average value of the voltage of the sub-nodes of the first voltage sampling node 31 and the average value of the voltage of the sub-nodes of the second voltage sampling node 32 is realized, and the first current sensing signal OUT1 after the average processing is obtained by the subtraction operation circuit 01.

[0046] The analog-to-digital converter 02 converts the first current sensing signal OUT1 into the second current sensing signal OUT2. The first current sensing signal OUT1 is an analog signal, which can represent the current flowing through the shunt resistor. In the analog circuit control, the first current sensing signal OUT1 can be directly used as the control signal of the system as the final output. In the digital circuit, the second current sensing signal OUT2 is used as the final output, or the first current sensing signal OUT1 is used as the final output and converted into a digital signal by the analog-to-digital converter in the digital circuit to realize digital control. That is, the analog-to-digital converter 02 can be selectively configured according to specific requirements.

[0047] In the embodiment, the subtraction operation circuit 01 includes an operational amplifier U1, a first resistor R1, a second resistor R2 and eight access resistors R3.

[0048] The first resistor R1 is connected between the negative input end and the output end of the operational amplifier U1, and the second resistor R2 is connected between the positive input end of the operational amplifier U1 and the ground. The sub-nodes of the first voltage sampling node 31 are respectively connected to the negative input end of the operational amplifier U1 through one access resistor R3, and the sub-nodes of the second voltage sampling node 32 are respectively connected to the positive input end of the operational amplifier U1 through one access resistor R3. The resistance values of the first resistor R1, the second resistor R2 and the eight access resistors R3 are equal. The voltage value VOUT1 of the first current sensing signal OUT1 output by the operational amplifier U1 is V2-V1, V2 is the voltage of the positive input end of the operational amplifier U1, and V1 is the voltage of the negative input end of the operational amplifier U1.

[0049] The shunt resistor provided by the application is provided with four or more assembly holes, and at least two first voltage sampling nodes and at least two second voltage sampling nodes are arranged at two ends of the resistance element respectively, so as to construct two or more current sampling paths in the resistance element, when the resistance distribution of the resistance element is changed in uniformity due to the deviation of the bolt mounting torque, the distribution density of the total current on different current paths is shifted, the current size on each current path is changed, or increased or decreased, and the voltage at both ends of each current detection path is increased or decreased, the shunt resistor of the application independently sets the voltage sampling nodes of the multiple current sampling paths, can average the sampling voltage on each current detection path, and can offset the current increase and decrease on each current path to a certain extent, so that the deviation of the current detection value after the average processing from the ideal value is reduced, and the accuracy of current detection is improved.

[0050] The current sensor provided by the application is provided with the shunt resistor and the subtraction operation circuit, the voltage sampling nodes at both ends of the resistance element of the shunt resistor are connected to two input ends of the subtraction operation circuit in parallel respectively, the output signal of the subtraction operation circuit is the average value of the voltage on each current detection path of the resistance element, the current increase and decrease on different current detection paths can be offset to a certain extent, the influence of the current density deviation caused by the deviation of the bolt mounting torque on the accuracy of current detection is reduced, and the reliability of current detection is improved.

[0051] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0052] The above-described embodiments only express several specific embodiments of the present application, which are described in detail and specifically, but cannot be understood as the limitation of the patent scope of the present application. It should be noted that, for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A shunt resistor characterized in that, The shunt resistor comprises a longitudinally distributed resistor element and two terminals, wherein, the terminals are extended from two ends of the resistor element, and at least two assembly holes are transversely arranged in each of the terminals; a first end of the resistor element is provided with at least two first voltage sampling nodes arranged at intervals, and a second end of the resistor element is provided with at least two second voltage sampling nodes arranged at intervals, the number of the first voltage sampling nodes is equal to the number of the second voltage sampling nodes, and the first voltage sampling nodes and the second voltage sampling nodes are arranged in a one-to-one symmetric manner with respect to the resistor element to form at least two current detection paths in the resistor element; wherein two assembly holes are arranged on each of the terminals, the first voltage sampling nodes are provided with four, and the current detection paths are uniformly and interval arranged along the transverse direction, and the assembly holes on the two terminals are arranged in a one-to-one symmetric manner with respect to the resistor element; a plurality of voltage sampling nodes are independently arranged to average the sampling voltage on each current detection path.

2. A current sensor, characterized by The shunt resistor comprises a longitudinally distributed resistor element and two terminals, wherein, the terminals are extended from two ends of the resistor element, and at least two assembly holes are transversely arranged in each of the terminals; the shunt resistor is fixed to the printed circuit board through bolts and the terminals; a first end of the resistor element is provided with at least two first voltage sampling nodes arranged at intervals, and a second end of the resistor element is provided with at least two second voltage sampling nodes arranged at intervals, the number of the first voltage sampling nodes is equal to the number of the second voltage sampling nodes, and the first voltage sampling nodes and the second voltage sampling nodes are arranged in a one-to-one symmetric manner with respect to the resistor element to form at least two current detection paths in the resistor element; the first voltage sampling nodes are connected in parallel to a first input end of the subtraction operation circuit, and the second voltage sampling nodes are connected in parallel to a second input end of the subtraction operation circuit; the current sensor provides a first current sensing signal at the output end of the subtraction operation circuit, which represents the current flowing through the shunt resistor; wherein two assembly holes are arranged on each of the terminals, the first voltage sampling nodes are provided with four, and the current detection paths are uniformly and interval arranged along the transverse direction, and the assembly holes on the two terminals are arranged in a one-to-one symmetric manner with respect to the resistor element; the output signal of the subtraction operation circuit is the average value of the voltage on each current detection path of the resistor element.

3. The current sensor of claim 2, wherein, an analog-to-digital converter is further included, an input end of the analog-to-digital converter is connected to an output end of the subtraction operation circuit, and the current sensor provides a second current sensing signal at an output end of the analog-to-digital converter, which represents the current flowing through the shunt resistor.

4. The current sensor of claim 2, wherein, the subtraction operation circuit comprises an operational amplifier, a first resistor, a second resistor, and a plurality of access resistors, wherein, the first resistor is connected between the negative input end and the output end of the operational amplifier; the second resistor is connected between the positive input end and the ground of the operational amplifier; the first voltage sampling nodes are respectively connected to the negative input end of the operational amplifier through one of the access resistors; The second voltage sampling node is connected to the positive input end of the operational amplifier through one of the access resistors respectively; The access resistors have the same resistance.

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