Detection circuit and method of temperature sensor

Abstract

The invention discloses a detection circuit and method of a temperature sensor, wherein the detection circuit comprises or relates to a temperature sensor Rx to be detected, an analog quantity input module, a programmable logic controller PLC (programmable logical controller) and a power supply E, and further comprises a Wheatstone bridge consisting of a sample temperature sensor R1, a second resistor R2, a third resistor R3 and the detected temperature sensor Rx. The detection circuit and method of the temperature sensor in the invention overcome the influence of the change of ambient temperature on the test result. According to the invention, the judgment range for detection can be reduced from the range of the detected temperature sensor Rx from 770Omega to 3378Omega, to the range froma resistance difference value plus 200Omega to the resistance difference value minus 200 (corresponding to 0.5V output voltage of the Wheatstone bridge and below), wherein the resistance difference value is between the detected temperature sensor and the sample temperature sensor R1, thereby sufficiently implementing efficient test on the stability and reliability of the detected temperature sensor. The detection circuit and method of the temperature sensor are convenient in implementation, low in implementation cost and very suitable for workshop online test.

Description

technical field [0001] The invention relates to a detection circuit and method of a temperature sensor, in particular to a detection circuit and method of a temperature sensor on an automobile air conditioner. Background technique [0002] There are many temperature sensors installed on the car air conditioner. These temperature sensors are an important basis for the control and adjustment of the air conditioner by the vehicle controller. Therefore, in the final inspection of the air-conditioning assembly, the detection of the temperature sensor is particularly important. [0003] In the prior art, a general measuring circuit of a programmable logic controller (PLC) is usually used to detect resistance performance. The method is to directly apply a voltage at both ends of the temperature sensor under test, read the current value passing through the temperature sensor under test, calculate to obtain the resistance value of the temperature sensor under test, and then compare ...

AI Technical Summary

Problems solved by technology

Such a measurement method needs to accurately measure the ambient temperature, and needs to calculate the upper and lower limits of the theoretical resistance value at the ambient temperature in real time, so it will bring higher requirements to the software and hardware of the test bench

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