Temperature acquisition system in multiple channels suitable to examination of microgravity liquid

Abstract

The invention relates to a multichannel temperature collecting system applied to micro-gravity fluid test, comprising interface filter circuit, multichannel switching module, thermoelectric couple temperature collecting module, two-stage signal amplifying module, A / D collecting module, couple failure detecting alarming module, central control unit and voltage stabilizing power supply module, where the temperature sensor is a thermoelectric couple to collect small temperature signal and completes multichannel temperature data collection by analog switch; after passing through a thermoelectric couple amplifier, completing linearization and cold end compensation, and amplifying the signal of the thermoelectric couple, where the linear output absolute value is 10 mv / deg.C, and after amplifying by the second-stage operational amplifier, making the signal output range is 0-5 V / 10V, corresponding to the whole temperature range of the fluid testing device, such as (0-120 deg.C); converting the temperature analogue quantity into digital quantity through the A / D collecting module and inputting the digital quantity into the central control unit. The system is simple in structure, and has high temperature measuring stability and good consistency.

Description

technical field [0001] The invention relates to a multi-channel temperature acquisition system suitable for microgravity fluid tests, in particular to a multi-channel temperature acquisition system applied in the field of aerospace. Background technique [0002] Thermocouple is one of the most commonly used temperature sensors. It has simple structure, stable performance and high temperature measurement accuracy. It has been widely used in the field of measurement and control. But it has its own complexity of nonlinearity and cold junction temperature compensation. In the conventional thermocouple temperature measurement, the cold junction compensation on the ground often uses the freezing point method, constant temperature method, etc. These methods cannot be realized in space, let alone meet the requirements of aerospace; most of the space missions use hardware circuits to linearize thermocouples. Although it can be used for space missions, such as bridge circuits, etc., ...

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Problems solved by technology

But it has the complexity of nonlinearity and cold junction temperature compensation

In the conventional thermocouple temperature measurement, the cold junction compensation on the ground often uses the freezing point method, constant temperature method, etc. These methods cannot be realized in space, let alone meet the requirements of aerospace; most of the space missions use hardware circuits to linearize thermocouples. Although it can be used for space missions, such as bridge circuits, etc., due to the accuracy problems of the resistance capacitor devices, the consistency is relatively poor, the compensation accuracy is low, and it brings certain difficulties to debugging and calibration. It is difficult to meet the high-performance and high-reliability requirements of current space missions; especially if these methods are to be realized in space, aerospace-grade radiation-resistant devices or 883B-level or higher devices must be used, and there are no thermocouple-specific amplifiers in these devices. Using a general-purpose amplifier makes the design complex, difficult to debug, large in size and power consumption, low in reliability, high in cost, and poor in consistency for multi-channel systems

[0003] For the linearization of thermocouples, software nonlinear corrections are mainly used, such as piecewise linearization, look-up table method, etc., but these algorithms have a certain loss of precision, and the operation speed is slow, which cannot meet the high performance and high reliability of space missions. requirements

[0004] With the rapid development of microelectronics technology and the increasing demand for high performance in space missions, the existing aerospace-grade radiation-resistant devices / 883B-level and above devices are far from meeting the needs of high-performance systems for space vehicles, making high-performance commercial The application of the device Commercial-Off-The-Shelf (COTS) in the space becomes possible

There are some dedicated thermocouple amplifiers with cold junction compensation and linearization in commercial devices, such as figure 1 The example shown is a typical circuit implementation, which can be used in a temperature acquisition system where the sensor is a thermocouple, but there is no corresponding device product with the same performance above the military grade

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