High accuracy multi-channel temperature signal acquisition device

Abstract

The invention discloses a high accuracy multi-channel temperature signal acquisition device. When temperature measurement platinum resistors are used to measure temperature, the constant current of a constant current source is transmitted to each temperature measurement platinum resistor through a first group of analogue switches; the other end of each resistor is grounded; at the same time, a second group of analogue switches are employed to acquire the voltage at two ends of each temperature measurement platinum resistor so that four-wire system connection for each temperature measurement platinum resistor is realized; as no current exists between each pair of input ends of the second group of analogue switches and each resistor, that is, no resistance is generated, the lead resistance can be effectively eliminated and the temperature measurement accuracy can be improved; an analogue circuit part and a digital circuit part employ a photoisolator to perform fine isolation so as to guarantee achievement of higher measurement accuracy; the temperature measurement accuracy for a temperature measurement circuit reaches 0.004DEG C within the -100DEG C to 50DEG C temperature measurement scope, and the linearity for the temperature measurement circuit reaches 0.0135%; and the constant current source current is set as 9.8mA through an RJ711 precise alloy foil resistor so as to eliminate the self-heating effect of each temperature measurement resistor and guarantee that the voltage of the temperature measurement platinum resistor Pt100 is not too low.

Description

technical field [0001] The invention relates to the technical field of small signal detection, in particular to a high-precision multi-channel temperature signal acquisition device. Background technique [0002] Temperature is a common and important physical parameter in the production process and scientific experiments. It is the main condition for high-quality, high-yield, low-consumption and safe production. The premise of precise temperature control is high-precision temperature measurement. Therefore, high-precision multi-channel temperature signals Acquisition technology is widely used in fields such as electric power, chemical industry, petroleum and aerospace. [0003] The existing technical methods include: the two-wire measurement method makes the actual measurement value too high due to the additional error brought by the wire resistance, which is generally used in occasions where the measurement accuracy is not high; the advantage of the general bridge temperatur...

AI Technical Summary

Problems solved by technology

[0003] The existing technical methods include: the two-wire measurement method makes the actual measurement value too high due to the additional error brought by the wire resistance, which is generally used in occasions where the measurement accuracy is not high; the advantage of the general bridge temperature measurement circuit is that it uses 3 A wire connects the Pt sensor and the measurement circuit, and the equal wire lengths on both sides of the Pt sensor are respectively added to the bridge arms on both sides. This can significantly reduce the measurement error caused by the wire resistance, but it cannot eliminate the measurement error; two The three-wire temperature measurement circuit composed of constant current sources, the reliability of two constant current sources is lower than that of one constant current source circuit, and the output current of the two constant current sources is required to be exactly the same, and the resistance value requirements of the two constant current sources higher

The existing technical methods do not completely isolate the digital circuit part from the analog circuit part, so it is difficult to improve the accuracy of temperature measurement

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