Non-contact voltage and current measuring device and method thereof

Abstract

The invention discloses a non-contact voltage and current measuring device and a method thereof, and relates to the technical field of no direct contact with a conductor. The device comprises a shell, a metal induction pole plate of the non-contact alternating current voltage sensor, a metal grounding shielding pole plate, a signal processing unit and a non-contact current transformer for measuring alternating current signals. Wherein the conductor and the metal induction pole plate form a primary side coupling capacitor, the metal induction pole plate and the metal grounding shielding pole plate form a secondary side coupling capacitor, the signal processing unit is connected with the metal induction pole plate, and the coupling capacitors are connected in series to sense an alternating current voltage waveform. The signal processing unit uses the AC voltage waveform and the scaling factor of the capacitor to obtain the to-be-measured voltage of the conductor. According to the device, the installation time is shortened, the to-be-detected voltage and the to-be-detected current of the alternating current conductor can be determined without interrupting a power supply, and the device can be used for detecting equipment faults or metering power.

Description

Technical Field

[0001] The invention relates to the field of voltage detection and current detection, in particular to a non-contact voltage and current measuring device and method thereof. Background Art

[0002] The prerequisite for safe and stable operation of the power system is the accurate measurement of the electrical parameters in the power system. Voltage and current are the key electrical parameters in the power system.

[0003] The voltage and current measurement in the power system is mainly achieved through the transformer. The voltage transformer is widely used in the power system, and its accuracy plays a very important role in electric energy metering, relay protection, power system fault analysis, etc. At present, the electromagnetic voltage transformer is mainly used in the power system. The traditional electromagnetic voltage transformer has the problems of large size and increasing insulation difficulty with the increase of voltage level. At the same time, due to the iron core, it may cause ferromagnetic resonance overvoltage and a smaller dynamic range caused by ferromagnetic saturation. In addition, the existing measurement devices often have single functions and are difficult to achieve efficient integration and intelligent processing. They are increasingly unsuitable for the development trend of the current intelligent power grid. The non-contact voltage and current sensor has the advantages of simple insulation structure, no magnetic saturation, large transient response range, small size, and output signal can be directly connected to microcomputer equipment, etc., and has great application prospects. Summary of the invention

[0004] Based on the above problems, the technical solution of the present invention provides a non-contact voltage and current measurement device and method thereof to solve the problems of single measurement function of the device, limited measurement bandwidth, and excessive space required for installation.

[0005] The non-contact voltage and current measurement device proposed in the present invention uses non-contact capacitive coupling technology to measure the voltage signal in the AC conductor, which allows accurate voltage measurement of properly shaped and scaled waveforms, not just peak detection, and does not require physical contact with the conductor.

[0006] The technical solution adopted by the present invention is as follows: a non-contact voltage and current measuring device, including an AC current sensor, an AC voltage sensor, a signal processing unit and a shell; the shell is composed of an upper shell and a lower shell connected by a hinge; the AC voltage sensor includes a metal sensing plate, a metal grounding shielding plate, an upper support body and a lower support body, and the AC current sensor is a current transformer with an upper magnetic core and a lower magnetic core; the upper magnetic core and the lower magnetic core are closed together to form a complete ring surrounding the measurement area.

[0007] Furthermore, the metal grounded shielding plate is provided with a grounding wire, which is used to transmit other interference electric field signals to the ground when collecting signals; the metal sensing plate and the metal grounded shielding plate are made of metal materials with good conductivity, such as copper, silver, etc.; the metal sensing plate is provided with a signal transmission line, which is used to transmit the voltage signal induced by the sensing plate to the signal processing unit.

[0008] Furthermore, a metal grounded shielding plate is provided on the inner surface of the housing to form a Faraday cage around the measuring area.

[0009] Furthermore, the AC current sensor, AC voltage sensor, and signal processing unit are all placed in an openable housing, and the housing is made of ABS. The housing includes an upper housing and a lower housing, and is an openable structure connected by a hinge. The hinge connection ensures that the housing has good stability during the opening and closing process and is easy to operate; the housing is made of ABS material, which has good insulation, mechanical strength, and corrosion resistance, and can effectively protect the internal components from the influence of the external environment, while ensuring the accuracy of the measurement and the durability of the device.

[0010] Furthermore, the sensing plate of the AC voltage sensor is insulated from the grounded shielding plate.

[0011] Furthermore, the metal sensing plate is composed of an upper metal sensing plate and a lower metal sensing plate; when the housing is closed, the upper metal sensing plate and the lower metal sensing plate are in a connected state. The upper metal sensing plate and the lower metal sensing plate are fixed by an upper support body and a lower support body, and together with the metal grounding shielding plate, form a stable capacitive coupling structure for accurately sensing AC voltage signals.

[0012] Furthermore, the AC current sensor is a current transformer, wherein the upper magnetic core is supported by an upper support body and placed inside an upper shell, and the lower magnetic core is supported by a lower support body and placed inside a lower shell, and the above parts together form a complete measurement area.

[0013] Furthermore, the core of the AC current sensor is made of ferrite or nanocrystalline material.

[0014] Furthermore, the device also includes a signal processing unit, which includes a voltage signal acquisition circuit, a current signal acquisition circuit, a power supply circuit, an MCU module and a wireless transmission module.

[0015] Furthermore, the voltage signal acquisition circuit and the current signal acquisition circuit are respectively connected to the metal sensing plate and the coil of the current transformer. The voltage signal acquisition circuit and the current signal acquisition circuit are also provided with an overvoltage protection circuit and a proportional amplification circuit, and are connected to the MCU module.

[0016] Furthermore, the MCU module receives an analog signal from a signal acquisition circuit, and an A / D module in the MCU converts the analog signal into a digital signal and connects to the wireless transmission module.

[0017] Furthermore, the wireless transmission module sends the digital signal after A / D conversion to the client.

[0018] Furthermore, the power supply circuit is respectively connected to each module to provide a working voltage.

[0019] Another object of the present invention is to provide a non-contact voltage and current measurement method, using the above device, first, the wire to be measured is passed through the measurement area; then, the voltage signal is sensed by the coupling capacitor formed by the metal sensing plate and the wire to be measured, and the current transformer measures the current signal; then, the signal processing unit amplifies and performs analog-to-digital conversion on the collected signal; finally, the wireless transmission module sends the processed data to the client to realize remote monitoring and data transmission;

[0020] The metal sensing plate and the wire to be measured form a primary coupling capacitor, and the voltage of the wire to be measured is obtained by the following relationship:

[0021]

[0022] Where: C1 is the primary coupling capacitor, C2 is the secondary coupling capacitor, H(s) is the voltage sensor gain change, V o (s) is the output voltage V of the sensing plate i (s) is the voltage of the conductor to be measured, R m is the sampling resistor;

[0023] The current transformer is a split or integrated structure. According to the principle of electromagnetic induction, the large current on the side of the conductor to be measured is proportionally converted into a small current on the secondary side, which is measured by a range meter. The conversion relationship is:

[0024]

[0025] Where: I1 is the rated current of the primary coil, I2 is the rated current of the secondary coil, and K is the coil turns ratio.

[0026] The present invention provides a non-contact voltage and current measurement method, which can obtain the voltage and current values ​​of the conductor to be measured without direct electrical contact with the conductor to be measured and without comparison with other AC voltage and current signals.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The non-contact voltage sensor of the present invention does not need to be in direct contact with the conductor, and uses a non-contact capacitive coupling system and technology to measure the voltage signal in the AC conductor, allowing the measurement of appropriately scaled waveforms. The disclosed device reduces installation time, does not require power interruption, and can detect harmonics in the conductor voltage, which can be used to detect and predict equipment failures or performance problems;

[0029] 2. The combination form of the sensor is voltage and current integration. Compared with the traditional power transformer, one device can measure two electrical parameters. It occupies a small space, has a small volume, is light in weight, and has a low manufacturing cost.

[0030] 3. Compared with the traditional power transformer, the non-contact voltage and current integrated sensor uses space electric field sensing technology and has a simple insulation structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be described by way of examples and with reference to the accompanying drawings, which are not intended to limit the present invention.

[0032] Figure 1 The block diagram shows the operating components of the non-contact voltage and current measurement device and method proposed by the present invention.

[0033] Figure 2 An exploded isometric view of the non-contact voltage and current measurement device components is shown.

[0034] Figure 3 An assembly diagram of a non-contact voltage and current measuring device is shown.

[0035] In the figure, 100 is the measuring area, 101 is the upper shell, 102 is the upper hinge, 103 is the positioning hole, 104 is the fixing pin, 105 is the buckle, 106 is the convex hook, 107 is the lower hinge, 108 is the upper support body, 109 is the lower support body, 110 is the upper magnetic core, 111 is the lower magnetic core, 112 is the upper metal induction plate, 113 is the lower metal induction plate, 114 is the coil support frame, 115 is the lower shell, 116 is the electronic circuit, and 117 is the barb. DETAILED DESCRIPTION

[0036] The embodiments described herein are illustrative examples and in no way limit the disclosed technology to any particular size, configuration, or application of conductors. Repeated use of the phrases "in one embodiment," "in various implementations," "in certain embodiments," etc., does not necessarily refer to the same embodiment. Unless the context dictates otherwise, "detecting" and "measuring" are generally synonymous. For example, detecting an "AC waveform" generally refers to obtaining a measurement of a continuously varying AC current. The terms "electric" and "electrical" are generally synonymous, as are the terms "voltage" and "potential."

[0037] The specific implementation mode of the present invention is described in detail below with reference to the accompanying drawings:

[0038] Figure 1 The component block diagram of the non-contact voltage and current measurement device and method thereof according to an embodiment of the present invention generally includes a measurement area 100, an AC voltage sensor structure 240, an AC current sensor structure 260, an MCU module 230, a wireless communication 270, a power module 280, a ground shield 281, and a housing 150. The AC voltage sensor structure 240 and the AC current sensor structure 260 are electrically connected to the signal processing unit 116, and the voltage and current signals of the conductor to be measured are output to the signal processing unit 116. The power module 280 is electrically connected to the AC voltage sensor structure 240 and the AC current sensor structure 260 and the signal processing unit 116 to provide a working voltage. The signal processing unit 116 performs amplification operations, data transmission, etc. on the signals output by the AC voltage sensor 240 and the AC current sensor 260.

[0039] The housing 150 provides a measurement area, and the measurement area 100 is configured to place a conductor to be measured, such as an insulated copper wire.

[0040] The non-contact voltage and current measuring device further includes a ground shield 281 made of a material with high conductivity, such as a metal copper foil or a copper mesh. In various embodiments, the shield 281 can form a Faraday cage around a portion or all of the components of the non-contact voltage and current measuring device to prevent interference from the surrounding electric field, thereby affecting the measurement result.

[0041] The AC voltage sensor structure 240 includes a metal sensing plate 210, which forms a primary coupling capacitor with the conductor in the measurement area 100. The metal sensing plate 210 forms a secondary coupling capacitor with the ground shield 281. The primary coupling capacitor and the secondary coupling capacitor are connected in series. When there is a potential on the conductor to be measured, the metal sensing plate 210 will output an induced voltage, and the reference voltage of the conductor to be measured can be reconstructed through the capacitor voltage divider ratio. The AC voltage sensor structure 240 is also provided with a connection line (the reference potential is the earth).

[0042] The AC voltage sensor structure 240 is equipped with a voltage signal processing circuit 211, and the voltage signal processing circuit 211 is also equipped with an overvoltage protection circuit. When the voltage on the conductor to be measured is unstable, a higher voltage will be generated instantaneously. At this time, the induced voltage on the metal sensing plate 210 will also increase accordingly. In order to prevent the transient high voltage from damaging the back-end signal processing unit 116, an overvoltage protection circuit is configured here. In some instances, the overvoltage protection can be composed of devices such as diodes, TVS, and MOV. The voltage signal processing circuit 211 also includes an operational amplifier circuit. In some instances, it mainly includes a voltage follower, a proportional amplifier circuit, etc.

[0043] The AC current sensor structure 260 includes a current sensor 220 and a current signal processing 221. The current sensor 220 can be a split-core current transformer, an integrated core current transformer, a Rogowski coil, a giant magnetoresistance (GMR) sensor, a Hall effect sensor, etc. In some examples, the current signal processing 221 can process the current waveform and the voltage waveform and synchronize them in time to obtain a power factor based on the detected AC current and voltage signals. The AC current sensor structure 260 is also provided with a wiring line.

[0044] In some embodiments, the non-contact voltage and current measuring device includes a power module 280, which is configured to power the electronic circuit of the non-contact voltage and current measuring device. For example, the power module 280 may include an energy storage system, such as a capacitor or a battery; an external power source, such as a DC voltage source.

[0045] The contactless voltage and current measuring device also includes a signal processing unit 116, which mainly includes an MCU module 230 and a wireless communication 270. The MCU module 230 and the wireless communication 270 are electrically connected. The MCU module 230 is configured with an A / D analog-to-digital conversion circuit 231. When the voltage signal processing circuit 211 and the circuit signal processing circuit 221 output analog signals, the A / D analog-to-digital conversion circuit 231 can convert the analog signals into digital signals. The wireless communication module 270 sends the processed data to the client. In some embodiments, the MCU module 230 can be any logic processing unit, such as one or more central processing units CPU, digital signal processors (DSP), field programmable gate arrays (FPGA), etc. The wireless communication module 270 can be Bluetooth communication, WIFI communication, 4G communication, etc.

[0046] In order to improve the integration of the device and reduce the size of the device, the AC voltage sensor structure 240, the AC current sensor structure 260, the MCU module 230, the wireless communication 270, and the power module 280 can be integrated on a unified PCB board.

[0047] The contactless voltage and current measurement device may also include a subset or superset of the above components. Additional components may include, for example, a display screen (such as an LCD or OLED display screen), a speaker for playing audio signals, a feedback device for tactile output (such as vibration), such as a temperature sensor, a power management system, etc. In various embodiments, additional infrastructure and equipment may be present.

[0048] Figure 2An exploded isometric view of a non-contact voltage and current measuring device assembly according to an embodiment is shown. The non-contact voltage and current measuring device comprises an upper housing 101, an upper hinge 102, a positioning hole 103, a fixing pin 104, a buckle 105, a boss 106, a lower hinge 107, an upper support 108, a lower support 109, an upper magnetic core 110, a lower magnetic core 111, an upper metal induction plate 112, a lower metal induction plate 113, a coil support frame 114, a lower housing 115, an electronic circuit 116, and a barb 117. The housing comprises two parts: an upper housing 101 and a lower housing 115, wherein the upper housing 101 comprises an upper hinge portion 102, and the lower housing 115 comprises a lower hinge portion 107. The upper hinge portion 102 and the lower hinge portion 107 together form a structure that allows the upper housing 101 and the lower housing 115 to form an open and close structure and maintain a hinge connection, providing an advantageous way to place the conductor to be measured. When the upper housing 101 and the lower housing 115 are closed, the buckle 105 on the upper housing 101 engages with the boss 106 on the lower housing 115 to fix the non-contact voltage and current measuring device around the conductor to be measured. The hinge and closing mechanism shown are examples; alternative methods may include any of a variety of mechanisms, such as a locking pin fit, a screw connection, a magnetic connection, etc. between the upper housing 101 and the lower housing 115.

[0049] The non-contact voltage and current measuring device includes an upper support body 108, a lower support body 109, an upper metal induction plate 112 and a lower metal induction plate 113. The upper metal induction plate 112 is embedded in the upper support body 108, the lower metal induction plate 113 is embedded in the lower support body 109, and the lower support body is provided with a signal line placement hole. The upper magnetic core 110 is placed at a preset position of the upper support body 108, placed inside the upper shell 101, and fixed by a fixing pin 104. The lower magnetic core 111 is placed at a preset position of the lower support body 109, fixed to the coil support frame 114 by a barb 117, and placed inside the lower shell 115 to form a measurement area 100.

[0050] The contactless voltage and current measuring device includes a current transformer (CT), which is divided into two parts: an upper magnetic core 110 in an upper housing 101 and a lower magnetic core 111 in a lower housing 115. The upper magnetic core 110 and the lower magnetic core 111 together form a complete ring around the measuring area 100. The current transformer material can be ferrite or nanocrystalline magnetic core, etc. In some embodiments, the current transformer (CT) is a whole, rather than a split core.

[0051] The non-contact voltage and current measuring device further includes an electronic circuit 116 , which may include a voltage signal processing 211 , a current signal processing 221 , an MCU module 230 , a wireless communication 270 , and a power supply module 280 , and all these functions may be integrated into a single PCB.

[0052] Figure 3 An assembly diagram of a non-contact voltage and current measuring device of one embodiment is shown. The upper housing 101 and the lower housing 115 are closed, and the buckle 105 on the upper housing 110 engages with the boss 106 on the lower housing 115. This shows an elegant closure method, by which a person can simply pull the buckle 105 to release it from the boss 106 and open the non-contact voltage and current measuring device (by the hinge, which is not visible) to place the measuring device on or remove it from the conductor to be measured.

[0053] The non-contact voltage and current measurement method adopts the above device. First, the wire to be measured is passed through the measurement area; then, the voltage signal is sensed by the coupling capacitor formed by the metal sensing plate and the wire to be measured, and the current transformer measures the current signal at the same time; then, the signal processing unit amplifies and performs analog-to-digital conversion on the collected signal; finally, the wireless transmission module sends the processed data to the client to realize remote monitoring and data transmission;

[0054] The metal sensing plate and the wire to be measured form a primary coupling capacitor, and the voltage of the wire to be measured is obtained by the following relationship:

[0055]

[0056] Where: C1 is the primary coupling capacitor, C2 is the secondary coupling capacitor, H(s) is the voltage sensor gain change, V o (s) is the output voltage V of the sensing plate i (s) is the voltage of the conductor to be measured, R m is the sampling resistor;

[0057] The current transformer is a split or integrated structure. According to the principle of electromagnetic induction, the large current on the side of the conductor to be measured is proportionally converted into a small current on the secondary side, which is measured by a range meter. The conversion relationship is:

[0058]

[0059] Where: I1 is the rated current of the primary coil, I2 is the rated current of the secondary coil, and K is the coil turns ratio.

[0060] The non-contact voltage and current measurement method can obtain the voltage and current values ​​of the conductor to be measured without direct electrical contact with the conductor to be measured or comparison with other AC voltage and current signals.

[0061] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present application are merely examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are necessarily possessed by each embodiment of the present application.

[0062] It should also be noted that in the device and method of the present application, each component can be decomposed or reassembled, and these decompositions or reassemblies should be regarded as equivalent solutions of the present application.

[0063] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A non-contact voltage and current measuring device, characterized in that: It includes an AC current sensor, an AC voltage sensor, a signal processing unit and a shell; the shell is composed of an upper shell and a lower shell connected by a hinge; the AC voltage sensor includes a metal sensing plate, a metal grounding shielding plate, an upper support body and a lower support body, and the AC current sensor is a current transformer with an upper magnetic core and a lower magnetic core; The upper and lower cores close together to form a complete ring around the measurement area.

2. The non-contact voltage and current measuring device according to claim 1, characterized in that: The metal grounded shielding plate is provided with a grounding wire, which is used to transmit other interfering electric field signals to the ground when collecting signals; the metal sensing plate and the metal grounded shielding plate are made of metal materials with good conductivity; the metal sensing plate is provided with a signal transmission line, which is used to transmit the voltage signal induced by the sensing plate to the signal processing unit; the metal grounded shielding plate is arranged on the inner surface of the shell to form a Faraday cage around the measuring area.

3. The non-contact voltage and current measuring device according to claim 1, characterized in that: The AC current sensor, AC voltage sensor and signal processing unit are all placed in a shell made of ABS; the induction plate of the AC voltage sensor is insulated from the grounded shielding plate.

4. The non-contact voltage and current measuring device according to claim 1, characterized in that: The metal sensing plate consists of an upper metal sensing plate and a lower metal sensing plate; when the shell is closed, the upper metal sensing plate and the lower metal sensing plate are in a connected state; the upper metal sensing plate and the lower metal sensing plate are fixed by an upper support body and a lower support body, and together with the metal grounded shielding plate, form a stable capacitive coupling structure for accurately sensing AC voltage signals.

5. The non-contact voltage and current measuring device according to claim 1, characterized in that: The AC current sensor is a current transformer, whose upper magnetic core is supported by an upper support body and placed inside an upper shell, and whose lower magnetic core is supported by a lower support body and placed inside a lower shell, and the above parts together form a complete measurement area; the AC current sensor core is ferrite or nanocrystalline material.

6. The non-contact voltage and current measuring device according to claim 1, characterized in that: The signal processing unit includes a voltage signal acquisition circuit, a current signal acquisition circuit, a power supply circuit, an MCU module and a wireless transmission module.

7. The non-contact voltage and current measuring device according to claim 1, characterized in that: The voltage signal acquisition circuit and the current signal acquisition circuit are respectively connected to the metal sensing plate and the coil of the current transformer. The voltage signal acquisition circuit and the current signal acquisition circuit are also provided with an overvoltage protection circuit and a proportional amplification circuit, and are connected to the MCU module; the MCU module receives the analog signal from the signal acquisition circuit, and the A / D module in the MCU converts the analog signal into a digital signal and is connected to the wireless transmission module; the wireless transmission module sends the digital signal after the A / D conversion to the client; the power supply circuit is respectively connected to each module to provide a working voltage.

8. A non-contact voltage and current measurement method, using the device described in any one of claims 1 to 7, characterized in that After the following operations: first, the wire to be tested is passed through the measurement area; then, the voltage signal is sensed by the coupling capacitor formed by the metal sensing plate and the wire to be tested, and the current transformer measures the current signal; then, the signal processing unit amplifies and performs analog-to-digital conversion on the collected signal; finally, the wireless transmission module sends the processed data to the client to realize remote monitoring and data transmission; The metal sensing plate and the wire to be measured form a primary coupling capacitor, and the voltage of the wire to be measured is obtained by the following relationship: Where: C1 is the primary coupling capacitor, C2 is the secondary coupling capacitor, H(s) is the voltage sensor gain change, V o (s) is the output voltage of the sensing plate V i (s) is the voltage of the conductor to be measured, R m is the sampling resistor; The current transformer is a split or integrated structure. According to the principle of electromagnetic induction, the large current on the side of the conductor to be measured is proportionally converted into a small current on the secondary side, which is measured by a range meter. The conversion relationship is: Where: I1 is the rated current of the primary coil, I2 is the rated current of the secondary coil, and K is the coil turns ratio.

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