Energy pulse output method and device of electric energy meter and electric energy meter

Abstract

The invention relates to the field of electronics and discloses an energy pulse output method and an energy pulse output device of an electric energy meter, and the electric energy meter. Two low-pass filters with different performance are designed. When the effective value of a current is less than or equal to a preset threshold, the low-pass filter which has a longer step response time but has higher attenuation degree to a non-direct current low-frequency part is selected, so that the attenuation to the non-direct current low-frequency part of transient power is better and the energy pulsejitter when a small signal is input is improved. When the effective value of the current is more than the preset threshold, the low-pass filter which has lower attenuation degree to the non-direct current low-frequency part but has a shorter step response time is selected, so that the instantaneity of energy pulse output is not affected.

Description

technical field [0001] The invention relates to the field of electronics, in particular to an electric energy meter in the field of electronics. Background technique [0002] The energy meter samples the analog voltage and current through a Sigma-delta analog-to-digital converter (Σ-ΔADC) and converts them into their digital form, so that the subsequent metering circuit can calculate data such as electric energy, power, and effective value. [0003] The basic structure of the existing electric energy meter is as follows: figure 1 As shown, the voltage value U and the current value I are respectively converted into corresponding digital signals u and i through the Σ-Δ analog-to-digital converter, which respectively represent the digital signals of the voltage value and current value, and the instantaneous power p is obtained after multiplying u and i (t), the instantaneous power passes through a low-pass filter LPF1 to obtain filtered instantaneous power P1, and the filtered...

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Problems solved by technology

When the current value is relatively small, the I value in formula 2 is relatively small, and the noise remains unchanged, so the signal-to-noise ratio of the current signal is relatively low, and the signal-to-noise ratio of the instantaneous power is correspondingly relatively low, and the filtered instantaneous power also contains There is more noise, therefore, the jump value of the output frequency of the energy pulse is relatively large when the signal is small

However, if a low-pass filter with a greater degree of attenuation to the non-DC low-frequency part is selected, the beating of the small signal can be improved, but the greater the attenuation of the non-DC low-frequency part by LPF1, the longer the step response time of LPF1 , if the step response time of LPF1 is similar to the output pulse interval of energy pulse CF, it will affect the output of energy pulse CF

Due to the small energy pulse output interval when the signal is large, this determines that the step response time of LPF1 should be relatively short. Therefore, in the existing electric energy meter structure, the step response time is usually short but for the non-DC low frequency part. The attenuation is not good enough for the low-pass filter, which leads to the problem that the accuracy of the energy meter fluctuates relatively large when the small signal is input

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