CN218272490U

CN218272490U - Electronic current transformer

Info

Publication number: CN218272490U
Application number: CN202222032859.3U
Authority: CN
Inventors: 李兴相; 梁诚; 苑东康
Original assignee: Nanjing Kanglun Electronic Co ltd
Current assignee: Nanjing Kanglun Electronic Co ltd
Priority date: 2022-08-03
Filing date: 2022-08-03
Publication date: 2023-01-10
Anticipated expiration: 2032-08-03

Abstract

The utility model relates to a current transformer field especially relates to an electronic current transformer, and it includes electronic current transformer, include: a housing, an air-core coil and a circuit board; the shell comprises a first cavity and a second cavity, the first cavity is of an annular structure, the second cavity is communicated with the first cavity, the air-core coil is arranged in the first cavity, and the circuit board is arranged in the second cavity; the hollow coil comprises an annular framework and an enameled wire uniformly wound on the annular framework; the circuit board is provided with a signal conditioning circuit, an AD conversion circuit and a controller; the input end of the signal conditioning circuit is connected to the enameled wire, the output end of the signal conditioning circuit is connected to the input end of the AD conversion circuit, and the output end of the AD conversion circuit is connected to the controller. The utility model discloses no magnetism saturation and ferromagnetic resonance phenomenon problem, the precision is high.

Description

Electronic current transformer

Technical Field

The utility model relates to a current transformer field especially relates to an electronic type current transformer.

Background

The current transformer is a sensor which transmits the current information of the primary side of the power system to the secondary side in a certain proportion to realize power measurement. Traditional current sensor is electromagnetic induction type, along with the continuous improvement of electric wire netting voltage class, the electric power system user is more and more, and the load is bigger and bigger, and traditional electromagnetic induction type current transformer's iron core easily takes place the magnetic saturation phenomenon, influences measurement accuracy, and ferromagnetic resonance easily appears to the overvoltage that produces can harm electrical equipment.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing an electronic type current transformer, no magnetism saturation and ferromagnetic resonance phenomenon problem, the precision is high.

For solving the above technical problem, the technical scheme of the utility model is that: an electronic current transformer comprising: a housing, an air core coil and a circuit board;

the shell comprises a first cavity and a second cavity, the first cavity is of an annular structure, the second cavity is communicated with the first cavity, the air-core coil is arranged in the first cavity, and the circuit board is arranged in the second cavity;

the hollow coil comprises an annular framework and an enameled wire uniformly wound on the annular framework;

the circuit board is provided with a signal conditioning circuit, an AD conversion circuit and a controller; the input end of the signal conditioning circuit is connected to the enameled wire, the output end of the signal conditioning circuit is connected to the input end of the AD conversion circuit, and the output end of the AD conversion circuit is connected to the controller.

Preferably, the signal conditioning circuit comprises an amplifying circuit and a filtering circuit;

the input end of the amplifying circuit is connected to the enameled wire, the output end of the amplifying circuit is connected to the input end of the filter circuit, and the output end of the filter circuit is connected to the input end of the AD conversion circuit;

the amplifying circuit comprises an operational amplifier and a gain resistor connected to the gain end of the operational amplifier;

the filter circuit adopts a voltage-controlled voltage source second-order active low-pass filter.

Preferably, the operational amplifier in the amplifying circuit adopts an AD620 chip.

Preferably, the AD conversion circuit employs an AD7606 analog-to-digital converter.

Preferably, the controller adopts a single chip microcomputer STM32F103C8T6.

Preferably, the circuit board further comprises a communication circuit connected to the output of the controller, the communication circuit using a LAN8720A ethernet transceiver.

Furthermore, the annular framework is made of nonmagnetic materials, and ceramic is preferably adopted.

The utility model discloses following beneficial effect has:

the utility model adopts the hollow coil, the annular framework is made of non-magnetic material, and the problems of magnetic saturation and ferromagnetic resonance are avoided, thereby ensuring the stable operation of the mutual inductor; the utility model discloses a hollow coil measures behind being surveyed the electric current, enlargies and the filtering through signal conditioning circuit, then carries out analog-to-digital conversion back through AD conversion module and passes through controller output signal, the utility model discloses measurement accuracy is high.

Drawings

FIG. 1 is a block diagram schematically illustrating the structure of the present invention;

FIG. 2 is a schematic circuit diagram of an amplifying circuit in the present embodiment;

FIG. 3 is a schematic circuit diagram of a filter circuit according to the present embodiment;

fig. 4 is a schematic circuit diagram of an AD conversion circuit in the present embodiment;

FIG. 5 is a circuit schematic of a communication circuit in other embodiments;

FIG. 6 is a schematic diagram of an external structure of the housing in this embodiment;

FIG. 7 is a schematic diagram of the internal structure of the housing in this embodiment;

reference numerals: 1. a housing; 101. a first cavity; 102. a second cavity; 103. a core penetration hole; 104. a wire outlet hole; 2. an air-core coil; 201. an annular skeleton; 202. enameled wires; 3. a circuit board; 301. a signal conditioning circuit; 302. an AD conversion circuit; 303. and a controller.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1 to 7, the present invention is an electronic current transformer, which includes: comprising a housing 1, an air coil 2 and a circuit board 3.

With reference to fig. 1, 6 and 7, the housing 1 includes a first cavity 101 and a second cavity 102, the first cavity 101 is an annular structure, the annular structure forms a core hole 103 of the housing 1, the core hole 103 is used for a current to be measured to pass through, the second cavity 102 is communicated with the first cavity 101, the air-core coil 2 is disposed in the first cavity 101, the circuit board 3 is disposed in the second cavity 102, a wire outlet 104 is disposed on a side portion of the housing 1, and the wire outlet 104 is communicated with the second cavity 102.

The hollow coil 2 comprises an annular framework 201 and an enameled wire 202 uniformly wound on the annular framework 201; the annular framework 201 is made of nonmagnetic materials, so that the output linearity of a sensing part of the current transformer is improved, the phenomenon of magnetic circuit saturation does not exist, and the current transformer has good reliability and transient response. The air-core coil 2 is not directly electrically connected with the current-carrying conductor of the measured current, and only surrounds the current-carrying conductor of the measured current, and the corresponding potential is induced along with the change of the magnetic field generated by the change of the measured current, so that the air-core coil is well electrically insulated from the measured loop.

With reference to fig. 1 to 5, the circuit board 3 is provided with a signal conditioning circuit 301, an AD conversion circuit 302, and a controller 303; the input end of the signal conditioning circuit 301 is connected to the enameled wire 202, the output end of the signal conditioning circuit 301 is connected to the input end of the AD conversion circuit 302, and the output end of the AD conversion circuit 302 is connected to the controller 303.

The signal conditioning circuit 301 includes an amplifying circuit and a filter circuit; the input end of the amplifying circuit is connected to the enameled wire 202, the output end of the amplifying circuit is connected to the input end of the filter circuit, and the output end of the filter circuit is connected to the input end of the AD conversion circuit 302;

referring to fig. 3, since the output voltage signal of the air-core coil 2 is weak, if the voltage signal is directly processed, a large error is caused, and meanwhile, the electronic circuit is easily interfered by a large amount, and even the signal is submerged, an amplification link is required to be added to make the output meet the subsequent requirements, and the amplification circuit includes an operational amplifier and a gain resistor connected to the gain end of the operational amplifier; the same-direction input end and the reverse-direction input end of the operational amplifier are connected with the enameled wire 202, in the embodiment, the operational amplifier adopts an AD620 chip, the cost is low, the offset voltage is low, the precision is high, and a resistor is connected in series with the first pin and the eighth pin of the AD620 chip to set the gain to realize amplification.

Referring to fig. 4, since the signal measured by the air-core coil 2 has interference of a high-frequency noise signal, in order to prevent the interference of the high-frequency signal and obtain an optimal output signal, the filter circuit uses a voltage-controlled voltage source second-order active low-pass filter to filter the interference signal.

Referring to fig. 5, in the electronic transformer, the primary side sensing part is an analog quantity of the measured current, and if an analog signal is transmitted to the secondary side through a cable for processing, the analog signal is affected by an external environment electromagnetic field in the transmission process, and the accuracy of the electronic transformer is further affected, so that the analog signal is secondarily converted to output a digital quantity in order to ensure the accuracy in the remote transmission process. In this embodiment, the AD conversion circuit 302 adopts an AD7606 analog-to-digital converter, which directly performs analog-to-digital conversion on the analog quantity to convert the analog quantity into a digital quantity, and the conversion precision is high.

In this embodiment, the controller 303 uses the single chip microcomputer STM32F103C8T6, and the chip has rich peripheral resources, so that not only can the external hardware connection of the system be greatly simplified, but also the power consumption of the system can be reduced.

In some other embodiments, the circuit board 3 further comprises a communication circuit connected to an output of the controller 303, the communication circuit being a LAN8720A ethernet transceiver. The LAN8720A chip is an ethernet transceiver chip designed with ultra-low power consumption, and supports 10Mbps/100Mbps ethernet transmission, and the controller 303 uses the LAN8720A chip to realize communication through an RJ45 network interface, and transmits measurement data to an upper computer in the PC terminal.

With reference to fig. 6 and 7, a first cavity 101 in the housing 1 is used for accommodating the air-core coil 2, a second cavity 102 is used for accommodating the circuit board 3, and the first cavity 101 is communicated with the second cavity 102 for connecting the terminal of the air-core coil 2 with the circuit board 3; the side wall of the shell 1 and the corresponding position of the second cavity 102 are provided with threading holes for the signal lines of the circuit board 3 to penetrate out so as to realize the connection of the circuit board 3 and an external upper computer.

The utility model discloses the part that does not relate to all is the same with prior art or adopts prior art to realize.

The foregoing is a more detailed description of the present invention that is presented in conjunction with specific embodiments, and it is not to be understood that the specific embodiments of the present invention are limited to these descriptions. To the utility model belongs to the technical field of ordinary technical personnel, do not deviate from the utility model discloses under the prerequisite of design, can also make a plurality of simple deductions or replacement, all should regard as belonging to the utility model discloses a protection scope.

Claims

1. An electronic current transformer, characterized in that: comprises a shell, an air core coil and a circuit board;

2. The electronic current transformer of claim 1, wherein: the signal conditioning circuit comprises an amplifying circuit and a filter circuit;

the amplifying circuit comprises an operational amplifier and a gain resistor connected to a gain end of the operational amplifier;

3. The electronic current transformer of claim 1, wherein: the operational amplifier in the amplifying circuit adopts an AD620 chip.

4. The electronic current transformer of claim 1, wherein: the AD conversion circuit adopts an AD7606 analog-to-digital converter.

5. The electronic current transformer of claim 1, wherein: the controller adopts a single chip microcomputer STM32F103C8T6.

6. The electronic current transformer of claim 1, wherein: the circuit board further comprises a communication circuit connected to the output end of the controller, and the communication circuit adopts a LAN8720A Ethernet transceiver.

7. The electronic current transformer of claim 1, wherein: the annular framework is made of nonmagnetic materials, and ceramic is preferably adopted.