Common-mode interference suppression circuit suitable for electromagnetic water meter and secondary instrument

Abstract

The invention discloses a common-mode interference suppression circuit suitable for an electromagnetic water meter and a secondary meter. The circuit comprises a voltage division circuit module, a differential amplification circuit module and a signal gating module, and the signal gating module is set as follows: when an excitation period non-starting signal output by an excitation control signal output end is received, the signal gating module controls gating between the first normal phase input end and the first partial voltage output end and gating between the second normal phase input end and the second partial voltage output end. when an excitation period starting signal output by the excitation control signal output end is received, the signal gating module controls the first normal phase input end and the first partial voltage output end to be disconnected, and the second normal phase input end and the second partial voltage output end to be disconnected. Therefore, the common-mode component in the voltage signal output by the instrument amplification circuit in the electromagnetic water meter can be deeply suppressed, so that the adaptive capacity of the electromagnetic water meter to various working conditions is further expanded.

Description

technical field [0001] The invention relates to the technical field of electronic circuits, in particular to a common-mode interference suppression circuit and a secondary instrument suitable for electromagnetic water meters. Background technique [0002] Existing electromagnetic water meters generally have the problem of high common-mode component signals in the output signal, which requires higher common-mode rejection capability of the pre-stage signal processing module in the secondary meter. Usually, a high common-mode rejection ratio instrumentation amplifier is generally used as a pre-amplification circuit, and metal pipes or grounding rings are used to meet the requirements of most working conditions. However, in the case of difficult or poor grounding of the instrument, the performance of the pre-amplifier circuit in the secondary instrument will be affected. In the prior art, this effect is not taken into account, so the final output signal of the electromagnetic ...

AI Technical Summary

Problems solved by technology

However, in the case of difficult or poor grounding of the instrument, the performance of the pre-amplifier circuit in the secondary instrument will be affected

In the prior art, this effect is not considered, so the final output signal of the electromagnetic water meter still has the problem that the common mode component is not sufficiently suppressed

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