Temperature detecting circuit based on thermistor

Abstract

The invention relates to a temperature detecting circuit based on a thermistor, in particular to the technical field of temperature measurement. The temperature detecting circuit based on the thermistor comprises an audion, the thermistor, a capacitor, an operational amplifier, a first resistor, a second resistor and a third resistor. An emitting electrode of the audion is connected with a grounded end. The thermistor and one end of the first resistor are respectively connected with a collector electrode of the audion. The other end of the thermistor is connected with a power source. The capacitor and a pin of the operational amplifier are respectively connected with the other end of the first resistor. The other end of the capacitor is connected with the grounded end. The pin of the operational amplifier is connected with one end of the second resistor and one end of the third resistor. The other end of the third resistor is connected with the grounded end. The other end of the second resistor is connected with an output end of the operational amplifier. The temperature detecting circuit based on the thermistor is simple in structure, high in detecting accuracy and capable of reducing development cost. A detecting method is enabled to be easy and convenient.

Description

Technical field: [0001] The invention relates to the technical field of temperature detection, in particular to a temperature detection circuit based on a thermistor. Background technique: [0002] The thermistor in the IGBT module needs to accurately detect its resistance value, and the temperature of the thermistor in the IGBT module is determined by looking up the table according to the resistance value. The accurate detection of the thermistor can improve the reliability of the IGBT and prevent the IGBT module from being damaged due to over-temperature. [0003] There are two commonly used thermistor detection circuits: [0004] The first one is to directly use a constant voltage source U1 to supply power through a known resistance resistor R1 and the thermistor Rξ to divide the voltage, and to detect the voltage U2 on the thermistor through A / D. Then the formula Rξ=U2*R1 / (U1-U2) method can be very accurate, but the A / D chip is expensive, and the cost of us...

AI Technical Summary

Problems solved by technology

This detection method is low in cost and easy to develop, but if the capacitance of the capacitor is selected to be small, the frequency of Uout is relatively high and it is difficult to accurately detect the resistance of Rξ

On the contrary, if the capacitance value of the capacitor is large, the accuracy of the capacitance value is low, and the temperature drift is large

Therefore, the detection accuracy of this circuit is low

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