Current sensing device and method

Abstract

An existing non-contact current measuring device does not filter environmental magnetic field components carried by a sensed magnetic field signal when sensing an induced magnetic field derived by a cable by using a magnetic sensor, so that the accuracy of a current value calculated by a rear-end processor is not high or the change is too large. Therefore, the invention provides a current sensing device and a current sensing method, and the current sensing device comprises at least one magnetic sensor, a signal receiving unit and a processor. Particularly, an environment magnetic field filtering unit and an effective current operation unit are planned in the processor; wherein the environmental magnetic field filtering unit is used for filtering an environmental magnetic field component carried by a magnetic field sensing signal, so that the effective current computing unit can compute a value of current transmitted by a cable according to a first magnetic field sensing signal; in this way, the sensing accuracy of the current sensing device on the current carried by the cable is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of current sensing, and more particularly to a current sensing device and method. Background Art

[0002] In recent years, Taiwan has paid more and more attention to the problems of global warming and energy shortage, so it often encourages people to save energy and electricity through incentives. For example, Taiwan Power Company often launches power saving incentives in the summer. In order to allow people to detect the power consumption of electrical appliances at home, power sensors such as smart meters have been launched on the market, which provide the function of checking the voltage, current, power consumption, power, and electricity charges of electrical appliances.

[0003] The Industrial Technology Research Institute has launched a non-contact power supply sensing device called "electricity meter sticky note", the technology of which is disclosed by US Patent Publication No. US2017 / 0023625A1. Figure 1 , is a three-dimensional diagram showing a non-contact three-phase three-wire power line measuring device disclosed in US Patent Publication No. US2017 / 0023625A1. Figure 1 As shown, the non-contact three-phase three-wire power line measuring device 1' mainly includes: a housing 10', a plurality of current sensors 11', a plurality of voltage sensors 12', and an electronic module 13'; wherein the housing 10' is used to cover three cables 2', and the plurality of current sensors 11' and the plurality of voltage sensors 12' are arranged on the outer surface of the housing 10'. In particular, the current sensor 11' is a magnetic sensor; on the other hand, referring to US Patent No. US9,007,077B2, it can be known that the voltage sensor 12' is a metal electrode.

[0004] In short, the non-contact power sensing device introduced by the Industrial Technology Research Institute has multiple functions, including: non-contact current measurement, non-contact voltage measurement, and power consumption calculation and display. However, since its non-contact current measurement is achieved by using one or more magnetic sensors (current sensor 11'), the inventor of this case found in the process of practical research that such non-contact current measurement technology will have obvious errors in current measurement due to the different thickness of the cable or the installation position of the housing 10'. Please refer to Figure 2 The magnetic field distribution diagram of two current transmission lines is shown. According to Ampere's (right-hand) law, if there is a long straight wire carrying a current of magnitude I and passing vertically through the paper, a circle with a radius of r can be drawn with the wire as the center, where the magnetic field magnitude at every point on the circumference of the circle is equal and can be calculated by the following formula:

[0005] Therefore, when using the multifunctional power sensor launched by the Industrial Technology Research Institute (i.e., the non-contact three-phase three-wire power line measuring device disclosed in U.S. Patent Publication No. US2017 / 0023625A1) to perform two current detections on a cable 2' carrying current, if the distance between the current sensor 11' and the cable 2' for the first current detection is different from the distance between the current sensor 11' and the cable 2' for the second current detection, the current values ​​measured by the two current detections will be significantly different. The reason is that the magnitude of the magnetic field derived from the current carried by the long straight conductor is inversely proportional to the radius r. On the other hand, the existing multifunctional power sensor does not filter out the DC component in the current signal when performing current detection, resulting in a large fluctuation in the accuracy of its current measurement value, which cannot be compared with conventional electric meters.

[0006] Engineers familiar with electromagnetic theory and non-contact current sensing technology can learn from the above description that the existing non-contact current sensing devices show a high degree of measurement inaccuracy and instability in practical applications. In view of this, the inventor of this case has made great efforts to study and invent, and finally developed a current sensing device and method of the present invention. Summary of the invention

[0007] The existing non-contact current measuring device does not filter out the DC component in the current signal when performing current detection, resulting in a large change in the accuracy of the current value measured. At the same time, the existing non-contact current measuring device will have obvious errors in current measurement due to the different thicknesses of the cables to be tested or the differences in the installation positions of the measuring device. Therefore, the main purpose of the present invention is to provide a current sensing device and method to improve or solve the many defects of the above-mentioned prior art.

[0008] In order to achieve the main purpose of the present invention, the inventor of the present invention provides an embodiment of the current sensing device, comprising:

[0009] At least one magnetic sensor is located at an initial sensing position and is separated from a cable by a sensing distance; wherein the magnetic sensor senses a first induced magnetic field of the cable at the initial sensing position and outputs a first magnetic field sensing signal;

[0010] a signal receiving unit, electrically connected to the magnetic sensor to receive the first magnetic field sensing signal; and

[0011] a processor, electrically connected to the signal receiving unit, and having an environmental magnetic field filtering unit and an effective current calculation unit;

[0012] The environmental magnetic field filtering unit is used to filter out an environmental magnetic field component carried by the first magnetic field sensing signal, so that the effective current calculation unit can calculate a value of a current transmitted by the cable according to the first magnetic field sensing signal.

[0013] Furthermore, in order to achieve the main purpose of the present invention, the inventors of the present invention also provide an embodiment of the current sensing method, comprising the following steps:

[0014] (1) A current sensing device comprising at least one magnetic sensor, a signal receiving unit and a processor is provided; wherein the processor has an ambient magnetic field filtering unit and an effective current calculation unit;

[0015] (2) enabling the magnetic sensor to sense a first induced magnetic field of the cable at an initial sensing position and output a first magnetic field sensing signal;

[0016] (3) The processor receives the first magnetic field sensing signal output by the magnetic sensor through the signal receiving unit;

[0017] (4) The ambient magnetic field filtering unit filters out an ambient magnetic field component carried by the first magnetic field;

[0018] (5) The effective current calculation unit calculates a value of a current transmitted by the cable according to the first magnetic field sensing signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A three-dimensional diagram showing a non-contact three-phase three-wire power line measuring device disclosed in U.S. Patent Publication No. US2017 / 0023625A1;

[0020] Figure 2 A diagram showing the magnetic field lines of two current transmission lines;

[0021] Figure 3 A perspective view showing a first embodiment of a current sensing device of the present invention;

[0022] Figure 4 A structural diagram showing a first embodiment of a current sensing device of the present invention;

[0023] Figure 5 A partial exploded view showing the structure of a power plug having a current sensing device according to the present invention;

[0024] Figure 6 A top view showing the base of the power plug and the magnetic sensor;

[0025] Figure 7 To show the top view of the power plug and wires;

[0026] Figure 8 A data graph showing measured current relative to sensed current;

[0027] Fig. 9 A data graph showing measured current relative to sensed current;

[0028] Fig.10 A data curve diagram showing the stability of the sensing current;

[0029] Fig.11 A structural diagram showing a second embodiment of a current sensing device of the present invention;

[0030] Fig.12 A side cross-sectional view showing the cable and magnetic sensor;

[0031] Fig.13 A top view showing the base of the power plug, the magnetic sensor, and the sensing position adjustment unit; Fig.14 A perspective view showing a power plug;

[0032] Fig.15 A three-dimensional diagram showing a magnetic ring and a magnetic sensor;

[0033] Fig.16A A flow chart showing a current sensing method of the present invention;

[0034] Fig. 16B A flow chart showing a current sensing method of the present invention; and

[0035] Fig. 16C FIG. 4 is a flow chart showing the current sensing method of the present invention.

[0036] The accompanying drawings are denoted as follows:

[0037] 31 Base

[0038] 32 Top cover

[0039] 33 Electrical connection terminals

[0040] 2 Cables

[0041] 1 Current sensing device

[0042] 11 Magnetic sensor

[0043] 12 Signal receiving unit

[0044] 13 Processor

[0045] 14 Signal transmission unit

[0046] 10 Circuit Board

[0047] 16 Power supply unit

[0048] 131 Environmental magnetic field filtering unit

[0049] 132 Effective current calculation unit

[0050] 134 Microprocessor Unit

[0051] 4 Electronic devices

[0052] 17 Sensing position adjustment unit

[0053] 133 Sensing current correction unit

[0054] 18 Magnetic ring

[0055] 181 Gap

[0056] 171 Track Group

[0057] 172 Carrying parts

[0058] 173 Controls

[0059] Steps S1-S5

[0060] S6 Step

[0061] S6a-S8a Step 21 Wire

[0062] 22 Insulation sheath

[0063] Pin initial sensing position

[0064] P1 First adjustment sensing position

[0065] 1' Non-contact three-phase three-wire power line measurement device

[0066] 10' shell

[0067] 11' Current sensor

[0068] 12' Voltage Sensor

[0069] 13' Electronic Module

[0070] 2' Cable DETAILED DESCRIPTION

[0071] In order to more clearly describe the current sensing device and method proposed by the present invention, preferred embodiments of the present invention will be described in detail below with reference to the drawings.

[0072] First embodiment

[0073] The current sensing device of the present invention can be applied to any existing power supply device, such as a contactless power supply sensor, a power meter, a power outlet, a power plug, a power converter, a power adapter, or a power extension cord. Figure 3 and Figure 4 That is, a three-dimensional diagram and a structural diagram showing a first embodiment of the current sensing device of the present invention, and Figure 5 The figure is a partial exploded view showing the structure of a power plug having a current sensing device according to the present invention. Figure 5 It can be seen that the power plug 3 mainly includes: a base 31, a top cover 32, two electrical connection terminals 33, and two cables 2. Figure 3 and Figure 4 As shown, the current sensing device 1 of the present invention mainly includes: at least one magnetic sensor 11 , a signal receiving unit 12 , a processor 13 , and a signal transmitting unit 14 .

[0074] In order to make the current sensing device 1 of the present invention easy to integrate into the power plug 3, the signal receiving unit 12, the processor 13 and the signal transmission unit 14 can be arranged on a circuit board 10, and then the circuit board 10 is fixed in the base 31 of the power plug 3. According to the design of the present invention, the magnetic sensor 11 is located in an initial sensing position in the base 31 and is separated from one of the two cables 2 by a sensing distance. Usually, the two cables 2 are the live wire and the neutral wire, and the magnetic sensor 11 is arranged near the live wire (L). It is worth noting that a power supply unit 16 is also arranged on the circuit board 10 to supply the power required by the signal receiving unit 12, the processor 13 and the signal transmission unit 14. Of course, this power supply unit 16 is not limited to a power supply or a power converter, and can also be a battery or a voltage regulator.

[0075] With such a configuration, the processor 13 can control the magnetic sensor 11 to sense a first induced magnetic field of the cable 2 at the initial sensing position and output a first magnetic field sensing signal. Further, the processor 13 receives the first magnetic field sensing signal through the signal receiving unit 12, and filters out the environmental magnetic field component carried by the first magnetic field sensing signal through an environmental magnetic field filtering unit 131 inside it. Then, an effective current calculation unit 132 inside the processor 13 can calculate the value of a current transmitted by the cable 2 based on the first magnetic field sensing signal. Finally, a microprocessor unit 134 inside the processor 13 can transmit the calculated value of the current to an external electronic device 4 through the signal transmission unit 14, such as: a smart phone, a smart watch, smart glasses, a tablet computer, a laptop computer, or other electronic devices with a wireless transmission interface or a wired transmission interface.

[0076] Electronic engineers who are good at using magnetic sensing elements to implement current sensing technology should know that the magnetic sensor 11 senses the magnetic field derived from the current transmitted by the cable 2 based on the control of the processor 13, so that the processor 13 can use However, since the magnetic field signal sensed by the magnetic sensor 11 may include both the induced magnetic field of the cable 2 and the ambient magnetic field, if the processor 13 directly uses The formula for converting the first magnetic field sensing signal into a current signal may greatly differ from the actual value. For this reason, the present invention particularly plans an environmental magnetic field filtering unit 131 and an effective current calculation unit 132 inside the processor 13; wherein, the environmental magnetic field filtering unit 131 uses an environmental magnetic field filtering expression to complete the filtering of the environmental magnetic field, and the effective current calculation unit 132 uses an effective current expression to calculate the value of the current transmitted by the cable 2. The environmental magnetic field filtering expression and the effective current expression are respectively represented by the following formula (1) and formula (2), and the definitions of the algebra or variables in the two expressions are summarized in the following table (1).

[0077]

[0078] Table (1)

[0079]

[0080] Calibration method of sensing current

[0081] Figure 6 A top view showing the base of the power plug and the magnetic sensor, and, Figure 7 The figure shows the top view of the power plug and wires. Figure 6As shown, the magnetic sensor 11 is placed on the base 31 of the power plug 3 so that it is directly close to the conductor 21 of the cable 2. Figure 7 As shown, the magnetic sensor 11 is removed from the power plug 3 and placed near the insulating sheath 22 of the cable 2. After the magnetic sensor 11 measures the magnetic field signal of the conductor 21 at two locations, the environmental magnetic field filtering unit 131 of the processor 13 will filter out the environmental magnetic field component of the magnetic field signal, so that the effective current calculation unit 132 can then calculate the value of a current transmitted by the cable 2. Afterwards, the effective current calculation unit 132 and the sensing current correction unit 133 in the processor 13 can use the following mathematical expressions (I') and (II') to deduce the so-called current correction parameters and complete the current correction; wherein, the definitions of the algebraic or variable in the mathematical expressions (I') and (II') are summarized in the following table (2).

[0082]

[0083] Ical=(IRMs) / k,k=Imea /

[0084] Table (2)

[0085]

[0086]

[0087] Figure 8 and Fig. 9 Both show the data curve of the measured current relative to the sensed current. It should be noted that the data of the measured current is obtained by measuring the cable 2 using a standard measuring device (eg, a current measuring device). On the other hand, Figure 8 The sensing current data is measured by placing the magnetic sensor 11 inside the power plug 3 (reference Figure 6 ),and Fig. 9 The sensing current data is measured by placing the magnetic sensor 11 close to the insulating sheath 22 of the cable line 2 (reference Figure 7 ).Depend on Figure 8 It can be found from the data that the R-square value of the trend line of the sensed current measured by placing the magnetic sensor 11 inside the power plug 3 is closer to 1 than the sensed current measured by placing the magnetic sensor 11 close to the insulating sheath 22 of the cable 2. Please refer to Figure 2 The magnetic field distribution diagram of two current transmission lines is shown. According to Ampere's (right-hand) law, if there is a long straight wire carrying a current of magnitude I and passing vertically through the paper, a circle with a radius of r can be drawn with the wire as the center, where the magnetic field magnitude at every point on the circumference of the circle is equal and can be calculated by the following formula: Based on the theory of magnetic field equipotential lines, the magnetic field strength measured when the magnetic sensor 11 is placed inside the power plug 3 must be higher than the magnetic field strength measured when the magnetic sensor 11 is placed near the insulating sheath 22 of the cable 2. This is why the R-squared value of the trend line of the sensed current measured when the magnetic sensor 11 is placed inside the power plug 3 is closer to 1.

[0088] However, after completing the calibration procedure, if Fig. 9 As shown in FIG. 1 , the trend line of the sensed current measured by placing the magnetic sensor 11 close to the insulating sheath 22 of the cable 2 and the trend line of the sensed current measured by placing the magnetic sensor 11 inside the power plug 3 both have R square values ​​close to 1. In short, the R square value reflects the relationship of multiple linear regression, and the closer it is to 1, the higher the credibility of the obtained data. Fig.10 , is a data curve diagram showing the stability of the sensed current. In order to determine whether the calibration method of the sensed current is indeed helpful in improving the measurement accuracy of the current sensing device 1 of the present invention, the inventor of the present invention uses the data of the current directly carried by the wire 21 of the cable 2 as the calculation basis for the measurement accuracy of the current sensing device 1 of the present invention. Fig.10 It can be found that the measurement accuracy of the current sensing device 1 of the present invention can be controlled within ±0.5%.

[0089] Second embodiment

[0090] As can be seen from the above description, the present invention utilizes a method of planning an environmental magnetic field filtering unit 131 and an effective current calculation unit 132 inside the processor 13, so that the processor 13 can calculate the correct value of the sensing current while filtering out the environmental magnetic field component carried by the sensing magnetic field signal; at the same time, the sensing current correction unit 133 is further used and the standard measuring device is used to measure the current of the cable 2, so as to complete the correction of the current of the cable 2 measured by the current sensing device 1, thereby greatly improving the sensing accuracy of the current sensing device 1. Furthermore, the present invention proposes a second embodiment of the current sensing device 1.

[0091] Fig.11 FIG. 2 is a schematic diagram showing a second embodiment of the current sensing device of the present invention. Fig.11 and Figure 4 It can be found that the second embodiment of this current sensing device 1 further includes a set of sensing position adjustment units 17; wherein the sensing position adjustment unit 17 is used to displace the magnetic sensor 11 to adjust the initial sensing position to a first adjusted sensing position, so that the magnetic sensor 11 can sense a second induced magnetic field derived from the current transmitted by the cable 2 above the first adjusted sensing position.

[0092] Another way to calibrate the sensing current

[0093] Fig.12 The figure shows the side cross-section of the cable and magnetic sensor. Fig.12 As shown, assuming that the magnetic sensor 11 is at the initial sensing position P in The distance between the conductor 21 and the cable 2 is r, and the magnetic sensor 11 is at the first adjustment sensing position P 1 The distance between the wire 21 and the cable 2 is r+d. Thus, the sensing current calibration unit 133 can use the following mathematical expressions (I), (II) and (III) to calibrate the sensing current; wherein the definitions of the algebraic numbers or variables in the mathematical expressions (I), (II) and (III) are summarized in the following table (3).

[0094]

[0095]

[0096] Table (3)

[0097]

[0098] Since the value of r includes the thickness of the insulating sheath 22 of the cable 2 and the distance between the magnetic sensor 11 and the insulating sheath 22, the thickness of the insulating sheath 22 can be preset according to the empirical value, thereby determining the value of r. Continuing, based on the magnetic field data measured by the magnetic sensor 11 during the first sensing operation, the value of the current carried by the cable 2 can be calculated using mathematical expression (I). Further, as long as the current value calculated by mathematical expression (I) and the magnetic field data measured by the magnetic sensor 11 at the first adjustment sensing position P1 are substituted into mathematical expression (II), r' (that is, the correction value of r) can be calculated. After obtaining the value of r', Ical (that is, the corrected current value) can be calculated using mathematical expression (III). Simply put, it is first assumed that the current value measured by the magnetic sensor 11 at the initial sensing position Pin is correct; then, after the magnetic sensor 11 is moved a distance d, the second induced magnetic field is sensed. Based on the Biot-Savart law, the current value measured by the magnetic sensor 11 at the initial sensing position Pin should be equal to the current value measured by the magnetic sensor 11 at the first adjustment sensing position P1. Therefore, as shown in the above mathematical expression (II), it can be assumed that the current measured by the magnetic sensor 11 at the first adjustment sensing position P1 is equal to the current measured by the magnetic sensor 11 at the initial sensing position Pin, and then the magnetic field data measured by the magnetic sensor 11 at the first adjustment sensing position P1 and the moving distance d are substituted into the mathematical expression (II), so that the corrected distance (i.e., r') can be obtained.

[0099] In this way, even if the distance r varies with the thickness of the insulating sheath 22 of different cables 2, as long as r is calibrated using the first calibration method for sensing current proposed by the present invention, the correct sensing current value can be calculated using the Biot-Savart law, thereby improving the sensing accuracy of the current sensing device 1 of the present invention for the current transmitted by the cable 2.

[0100] Please continue reading Fig.13 , which is a top view showing the base of the power plug, the magnetic sensor, and the sensing position adjustment unit. Also, please refer to Fig.14 , is a three-dimensional diagram showing a power plug. Fig.11 , Fig.13 and Fig.14 It can be known that the exemplary embodiment of the sensing position adjustment unit 17 includes: a track set 171, a carrier 172 movable on the track set 171, and a control member 173 driving the carrier 172 to move. Among them, the track set 171 can be a track set with a slide groove or a track set with a tooth groove. In the calibration of the sensing current, it is only necessary to first use the control member 173 to make the carrier 172 move a distance on the track set 171 with the magnetic sensor 11, so that the current sensing device 1 can integrate the data of the first sensing operation and the second sensing operation, and then automatically complete the calibration of the sensing current. It must be emphasized that when the current sensing device 1 of the present invention is used to detect the current of any cable 2, it is not limited that the magnetic sensor 11 must be located inside the power plug 3. Therefore, the sensing position adjustment unit 17 can also be synchronously arranged on the outside of the power plug 3 in conjunction with the setting position of the magnetic sensor 11.

[0101] Please refer again Figure 3 , and also see Fig.15 The three-dimensional diagram of the magnetic ring and the magnetic sensor is shown. When implementing the current sensing device 1 of the present invention, a magnetic ring 18 can be sleeved on the cable 2, and the magnetic sensor 11 can be set in a notch 181 of the magnetic ring 18. In this way, the magnetic ring 18 can be used to guide the magnetic field derived from the current transmitted by the cable 2, so that the magnetic field passes through the notch 181, thereby improving the magnetic field sensing accuracy of the magnetic sensor 11. At the same time, an electromagnetic shielding layer can be further covered on the magnetic ring 18 to shield the external magnetic field and prevent the external magnetic field from interfering with the magnetic field derived from the current transmitted by the cable 2. It must be particularly noted that the magnetic sensor 11 is usually used to sense the magnetic field of the live wire among the two cables 2; therefore, when using the magnetic ring 18, the live wire must pass through the magnetic ring 18 and the neutral wire must be limited to be outside the magnetic ring 18.

[0102] Thus, the above description has completely and clearly described a plurality of embodiments of a current sensing device 1 of the present invention; next, a current sensing method of the present invention will be described below. Fig.16A , Fig. 16B and Fig. 16C is a flow chart showing the current sensing method of the present invention; wherein, Fig.16A There are five steps for the cable 2 (such as Figure 3 The five steps include the following steps:

[0103] Step S1: providing a current sensing device 1 including at least one magnetic sensor 11, a signal receiving unit 12 and a processor 13; wherein the processor 13 has an ambient magnetic field filtering unit 131 and an effective current calculation unit 132;

[0104] Step S2: enabling the magnetic sensor 11 to sense a first induced magnetic field of the cable 2 at an initial sensing position Pin, and output a first magnetic field sensing signal;

[0105] Step S3: the processor 13 receives the first magnetic field sensing signal output by the magnetic sensor 11 through the signal receiving unit 12;

[0106] Step S4: the ambient magnetic field filtering unit 131 filters out an ambient magnetic field component carried by the first magnetic field; and

[0107] Step S5 : the effective current calculation unit 132 calculates a value of a current transmitted by the cable 2 according to the first magnetic field sensing signal.

[0108] It should be noted that if the current sensing method is compiled into application software in the form of a library, a variable or an operand and is established in the first embodiment of the current sensing device 1 of the present invention (such as Figure 3 shown), then Fig. 16B The method includes a step for correcting the current measured by the cable 2; the execution content of the step is as follows:

[0109] Step S6 : Based on the current value calculated by the effective current calculation unit 132 and a measured current value measured by a current measuring device from the cable 2 , the sensed current correction unit 133 can correct the current value calculated by the effective current calculation unit 132 .

[0110] In step S4 and step S5, the environmental magnetic field filtering unit 131 uses an environmental magnetic field filtering expression to filter out the environmental magnetic field component, and the effective current calculation unit 132 uses an effective current expression to calculate the value of the current transmitted by the cable 2. The environmental magnetic field filtering expression and the effective current expression are represented by the equations (1) and (2) introduced above. In addition, in step S6, the effective current calculation unit 132 and the sensing current correction unit 133 use the mathematical expressions (I') and (II') introduced above to calculate the so-called current correction parameters and complete the current correction.

[0111] On the other hand, if the current sensing method is compiled into application software in the form of a library, variables or operands and is established in the second embodiment of the current sensing device 1 of the present invention (such as Fig.11 shown), then Fig. 16C There are three steps involved in correcting the current measured by the cable 2. The steps are as follows:

[0112] Step S6a: moving the magnetic sensor 11 so that the magnetic sensor 11 is located above a first adjustment sensing position P1;

[0113] Step S7a: enabling the magnetic sensor 11 to sense a second induced magnetic field of the cable 2 at the first adjusted sensing position P1 and output a second magnetic field sensing signal, and then repeating steps S3 to S5; and

[0114] Step S8 a : Based on the first magnetic field sensing signal and the second magnetic field sensing signal, the sensing current correction unit 133 corrects the value of the current transmitted by the cable 2 calculated by the effective current calculation unit 132 .

[0115] Furthermore, in step S8a, the effective current calculation unit 132 and the sensing current correction unit 133 use the mathematical expressions (I), (II) and (III) introduced above to calculate the so-called correction value of r and complete the current correction.

[0116] Thus, the above description has completely and clearly described the current sensing device and method of the present invention. From the above description, it can be known that the present invention has the following advantages:

[0117] (1) When the existing non-contact current measuring device uses a magnetic sensor to sense the induced magnetic field derived from the cable, it does not filter out the environmental magnetic field component carried by the sensed magnetic field signal, resulting in the current value calculated by its back-end processor to be inaccurate or vary too much. In view of this, the present invention proposes a current sensing device 1, comprising: at least one magnetic sensor 11, a signal receiving unit 12 and a processor 13. In particular, the present invention utilizes a method of planning an environmental magnetic field filtering unit 131 and an effective current calculation unit 132 inside the processor 13; wherein the environmental magnetic field filtering unit 131 is used to filter out an environmental magnetic field component carried by the magnetic field sensing signal, so that the effective current calculation unit 132 can calculate the value of a current transmitted by the cable 2 according to the magnetic field sensing signal, thereby improving the sensing accuracy of the current sensing device 1 for the current carried by the cable 2.

[0118] (2) On the other hand, the existing non-contact current measuring device may have obvious errors in current measurement due to the different thicknesses of the cables to be measured or the differences in the installation positions of the measuring device. In order to improve the defects of the prior art, the present invention further provides a sensing current correction unit 133 in the processor 13; thus, based on the value of the current calculated by the effective current calculation unit 132 and the value of a measured current measured by a current measuring device from the cable 2, the sensing current correction unit 133 can correct the value of the current calculated by the effective current calculation unit 132.

[0119] It must be emphasized that the above detailed description is a specific description of a feasible embodiment of the present invention, but the embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the technical spirit of the present invention should be included in the patent scope of this case.

Claims

1. A current sensing device, characterized in that: include: At least one magnetic sensor is located at an initial sensing position and is separated from a cable by a sensing distance; wherein the magnetic sensor senses a first induced magnetic field of the cable at the initial sensing position and outputs a first magnetic field sensing signal; a signal receiving unit, electrically connected to the magnetic sensor to receive the first magnetic field sensing signal; and a processor, electrically connected to the signal receiving unit, and having an environmental magnetic field filtering unit, an effective current calculation unit and a sensing current correction unit; The environmental magnetic field filtering unit is used to filter out an environmental magnetic field component carried by the first magnetic field sensing signal, so that the effective current calculation unit can calculate a value of a current transmitted by the cable according to the first magnetic field sensing signal; The environmental magnetic field filtering unit uses the following formula (1) to filter out the environmental magnetic field component carried by the first magnetic field sensing signal: The effective current calculation unit uses the following formula (2) to calculate the effective value of the current transmitted by the cable: The sensing current correction unit uses the following formula (3) to calculate a correction value of the current: I Cal =(I RMS ) / k,k=I mea / I i ………………(3); Where n is an integer, I i For this current, The current after filtering out the environmental magnetic field component; Among them, I RMS Represents the effective value of the current, I Cal is the correction value of the current, and I mea is a measured current obtained by measuring the cable using a current measuring device, and k is a current correction parameter.

2. The current sensing device according to claim 1, wherein: Also includes: A magnetic ring is sleeved on the cable and has a gap for the magnetic sensor to be arranged therein; wherein the magnetic ring is used to guide the magnetic field derived from the current transmitted by the cable to pass through the gap.

3. The current sensing device according to claim 1, wherein: Also includes: A power supply unit is used to supply power required by the signal receiving unit and the processor.

4. The current sensing device according to claim 1, wherein: The magnetic sensor, the signal receiving unit and the processor are arranged in a power supply device, and the power supply device can be any one of the following: a contactless power supply sensor, an electric meter, a power socket, a power plug, a power converter, a power adapter, or a power extension cord.

5. The current sensing device according to claim 1, wherein: Also includes: a signal transmission unit electrically connected to the processor, so that the processor can transmit the calculated value of the current to an external electronic device through the signal transmission unit; Wherein, the signal transmission unit is a wired transmission interface or a wireless transmission interface.

6. The current sensing device according to claim 2, wherein: Also includes: An electromagnetic shielding layer covers the magnetic ring.

7. The current sensing device according to claim 3, characterized in that: The power supply unit may be any of the following: a battery, a power supply, a power converter, or a voltage regulator.

8. A current sensing method, characterized in that: The following steps are involved: (1) A current sensing device comprising at least one magnetic sensor, a signal receiving unit and a processor is provided; wherein the processor has an ambient magnetic field filtering unit, an effective current calculation unit and a sensing current correction unit; (2) enabling the magnetic sensor to sense a first induced magnetic field of a cable at an initial sensing position and output a first magnetic field sensing signal; (3) The processor receives the first magnetic field sensing signal output by the magnetic sensor through the signal receiving unit; (4) The ambient magnetic field filtering unit filters out an ambient magnetic field component carried by the first magnetic field; (5) the effective current calculation unit calculates a value of a current transmitted by the cable according to the first magnetic field sensing signal; and (6) the sensing current correction unit corrects the current; The environmental magnetic field filtering unit uses the following formula (1) to filter out the environmental magnetic field component carried by the first magnetic field sensing signal: The effective current calculation unit uses the following formula (2) to calculate the effective value of the current transmitted by the cable: The sensing current correction unit uses the following formula (3) to calculate a correction value of the current; I Cal =(I RMS ) / k,k=I mea / I i ..................(3); Where n is an integer, I i For this current, The current after filtering out the environmental magnetic field component; Among them, I RMS Represents the effective value of the current, I Cal is the correction value of the current, and I mea is a measured current obtained by measuring the cable using a current measuring device, and k is a current correction parameter.

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