There is no limit to creativity, and the instrument is invented. Today, we introduce a national invention patent for authorization - single-phase energy meter zero line current measurement method and measurement circuit. The patent was applied for by Weisheng Group Co., Ltd. and was authorized to be announced on March 15, 2017.
Description
The invention relates to a single-phase electric energy meter zero line current measuring method and a measuring circuit.
Background of the invention
With the development of society, the popularity of various household appliances with large power consumption, and the increasing load of household electricity, electricity bills have become one of the important daily expenses of the family, and people pay more attention to electricity bills. Various types of tampering methods are constantly emerging, and the zero line measurement becomes an indispensable anti-tamper detection method for electric energy meters.
The existing neutral current measurement method generally uses a single current sensor to collect the neutral current. Due to the increase of the power load, the dynamic range of the neutral current sensor is relatively wide, and the dynamic range exceeds 1000:1, resulting in a corresponding increase in cost.
Summary of the invention
The object of the present invention is to provide a low-cost, high-reliability, and easy-to-implement single-phase electric energy meter zero line current measuring method and measuring circuit.
The method for measuring the zero-line current of the single-phase electric energy meter provided by the invention comprises the following steps: Step 1: using a current sensor to obtain a differential current value of the output of the live current and the input of the neutral current; and obtaining the current value of the live line In step two, the neutral current value is obtained in real time according to the differential current value and the live current value. The live current value is obtained using a live current sensor. The live current sensor uses an electromagnetic current transformer CT or manganese copper.
The figure is a schematic diagram of an embodiment of the invention
The method further includes setting a tampering determination threshold; comparing the ratio of the differential current value to the glazing current value to the tampering determination threshold, and if the ratio is greater than or equal to the tampering determination threshold, inferring that the watt meter is at Stealing status. The tampering determination threshold is the basis for determining the current tampering; the value is set according to the specifications and application conditions of the electric energy meter before leaving the factory.
A single-phase electric energy meter zero line current measuring circuit, comprising a live current sensor, a hot line input terminal, a live line output terminal, a neutral input terminal, a neutral output terminal, a load and an energy metering chip, wherein the circuit further comprises a differential The current sensor, the differential current sensor collects the differential current value of the live current output value flowing through the live line output terminal and the neutral current input value flowing through the neutral input terminal; the live line is input by the live input terminal, and then passes through the live current sensor. The sensor obtains the live current value and then outputs it via the live line output terminal; the neutral line is input by the neutral input terminal and then output by the neutral output terminal; the load is connected between the live output terminal and the neutral input terminal; the live current sensor is also coupled with the electrical energy. The metering chip is connected; the differential current sensor is also connected to the energy metering chip.
The output of the live current sensor is connected to an ADC port of the energy metering chip for collecting a line current value. The output of the differential current sensor is coupled to the ADC port of the energy metering chip for collecting the differential current value of the output of the live current and the input of the neutral current.
The invention adopts the differential measurement mode, and simultaneously samples the live current output and the neutral current input by using only one current sensor, thereby accurately obtaining the neutral current value and greatly reducing the technical requirement of the neutral current sensor, and the current measurement dynamic of the current sensor. The range is less than 100:1, which greatly reduces the dynamic range of current measurement, reduces the material cost of the sensor and the manufacturing cost, and also reduces the performance requirements and hardware cost of the zero-sampling channel ADC of the metering chip. In addition, the present invention can also judge whether the electric energy meter has theft electricity under the premise of setting the threshold value, and contribute to the anti-stealing work of the electric power department.
Article link: China Instrument Network http://
Description
The invention relates to a single-phase electric energy meter zero line current measuring method and a measuring circuit.
Background of the invention
With the development of society, the popularity of various household appliances with large power consumption, and the increasing load of household electricity, electricity bills have become one of the important daily expenses of the family, and people pay more attention to electricity bills. Various types of tampering methods are constantly emerging, and the zero line measurement becomes an indispensable anti-tamper detection method for electric energy meters.
The existing neutral current measurement method generally uses a single current sensor to collect the neutral current. Due to the increase of the power load, the dynamic range of the neutral current sensor is relatively wide, and the dynamic range exceeds 1000:1, resulting in a corresponding increase in cost.
Summary of the invention
The object of the present invention is to provide a low-cost, high-reliability, and easy-to-implement single-phase electric energy meter zero line current measuring method and measuring circuit.
The method for measuring the zero-line current of the single-phase electric energy meter provided by the invention comprises the following steps: Step 1: using a current sensor to obtain a differential current value of the output of the live current and the input of the neutral current; and obtaining the current value of the live line In step two, the neutral current value is obtained in real time according to the differential current value and the live current value. The live current value is obtained using a live current sensor. The live current sensor uses an electromagnetic current transformer CT or manganese copper.
The figure is a schematic diagram of an embodiment of the invention
The method further includes setting a tampering determination threshold; comparing the ratio of the differential current value to the glazing current value to the tampering determination threshold, and if the ratio is greater than or equal to the tampering determination threshold, inferring that the watt meter is at Stealing status. The tampering determination threshold is the basis for determining the current tampering; the value is set according to the specifications and application conditions of the electric energy meter before leaving the factory.
A single-phase electric energy meter zero line current measuring circuit, comprising a live current sensor, a hot line input terminal, a live line output terminal, a neutral input terminal, a neutral output terminal, a load and an energy metering chip, wherein the circuit further comprises a differential The current sensor, the differential current sensor collects the differential current value of the live current output value flowing through the live line output terminal and the neutral current input value flowing through the neutral input terminal; the live line is input by the live input terminal, and then passes through the live current sensor. The sensor obtains the live current value and then outputs it via the live line output terminal; the neutral line is input by the neutral input terminal and then output by the neutral output terminal; the load is connected between the live output terminal and the neutral input terminal; the live current sensor is also coupled with the electrical energy. The metering chip is connected; the differential current sensor is also connected to the energy metering chip.
The output of the live current sensor is connected to an ADC port of the energy metering chip for collecting a line current value. The output of the differential current sensor is coupled to the ADC port of the energy metering chip for collecting the differential current value of the output of the live current and the input of the neutral current.
The invention adopts the differential measurement mode, and simultaneously samples the live current output and the neutral current input by using only one current sensor, thereby accurately obtaining the neutral current value and greatly reducing the technical requirement of the neutral current sensor, and the current measurement dynamic of the current sensor. The range is less than 100:1, which greatly reduces the dynamic range of current measurement, reduces the material cost of the sensor and the manufacturing cost, and also reduces the performance requirements and hardware cost of the zero-sampling channel ADC of the metering chip. In addition, the present invention can also judge whether the electric energy meter has theft electricity under the premise of setting the threshold value, and contribute to the anti-stealing work of the electric power department.
Article link: China Instrument Network http://
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