Weak current detecting circuit of nitrogen-oxygen sensor

A nitrogen and oxygen sensor, weak current technology, applied in the direction of measuring current/voltage, only measuring current, instruments, etc., can solve the problem of complex detection of weak current detection circuit, to enhance anti-interference ability, reduce conversion error, reduce noise the effect of

Inactive Publication Date: 2019-01-18
HUAZHONG UNIV OF SCI & TECH
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  • Abstract
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Problems solved by technology

[0005] The detection of this weak current detection circuit is relatively complicated, which is mainly reflected in:

Method used

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  • Weak current detecting circuit of nitrogen-oxygen sensor
  • Weak current detecting circuit of nitrogen-oxygen sensor
  • Weak current detecting circuit of nitrogen-oxygen sensor

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Embodiment Construction

[0023] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

[0024] The weak current detection circuit provided by the present invention includes: a current-voltage conversion circuit, a differential low-pass filter and an amplifying circuit; first, a high-precision, low-temperature drift sampling resistor is connected to the signal loop to form a current-voltage conversion circuit. The original current signal is converted into a voltage signal, and its multiple is the value of the connected sampling resistor; then, the converted voltage signal flows into the differential low-pass filter circuit to filter out the radio frequency noise mixed in the weak voltag...

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Abstract

The invention discloses a weak current detecting circuit of a nitrogen-oxygen sensor, which comprises a current-voltage conversion circuit, a differential low-pass filter and an instrument operationalamplifier, which are connected in sequence. The current-voltage conversion circuit is formed by connecting a sampling resistor to a signal loop; the current-voltage conversion circuit is used for converting a current signal collected by a nitrogen-oxygen sensor into a voltage signal of N times; after high-frequency interference is filtered by the differential low-pass filter, the voltage signal is output after being accurately and effectively amplified by an instrument operational amplifier, wherein the value of N is equal to the value of resistance of the sampling resistor. The weak currentdetecting circuit of a nitrogen-oxygen sensor in the invention can accurately amplify the weak voltage signal. Such an instrument amplification circuit has the characteristics of low offset, low output error, high signal-to-noise ratio, high common-mode rejection ratio, high gain and the like.

Description

technical field [0001] The invention belongs to the field of signal detection, and more specifically relates to a weak current detection circuit applied to a vehicle nitrogen oxygen sensor. Background technique [0002] With the rapid development of the world economy, the total number of automobiles in the world continues to rise. The development of the automobile industry has greatly promoted the progress of human society, but due to the limitation of its power source, it has also greatly exacerbated environmental pollution and energy shortages. . The vehicle nitrogen and oxygen sensor detects the oxygen concentration in the vehicle exhaust and feeds back the detection results to the engine electronic control unit (ECU) to improve the fuel combustion utilization rate, and improves the catalytic efficiency of the three-way catalyst in the vehicle exhaust treatment system, effectively The reduction of harmful gas emissions including NO. [0003] The combustion utilization r...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R19/00G01N27/00
CPCG01N27/00G01R19/0092
Inventor 李曦曾成冯江涛王杰蒋建华邓忠华李怡
Owner HUAZHONG UNIV OF SCI & TECH
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