用差值比率法提高铂电阻测温仪表精度

提高配铂电阻测温仪表精度的关键是如何消除热电阻连接导线电阻随环境温度变化、放大器的零点漂移、放大倍数的变化对温度测量带来的影响。叙述了以三线制的铂电阻、标准电阻、恒流源及多路开关组成不同的输入通道 ,由单片机选通不同的输入通道将其输入量送入放大器放大 ,由电压 /频率转换器把电压信号转换为频率信号。由单片机测量各个通道的输入量所对应的频率信号 ,结合差值比率法来消除铂电阻连接导线电阻随上述变化对温度测量带来的影响。从而达到提高配铂电阻测温仪表精度的目的

Upgrading Thermometric Instrument Precision for Platinum Resistence with Differnce/Ratio Method

The key of upgrading thermometric instrument precision for platinum resistance is how to eliminate the influence owing to thermal resistance connecting wire resistance as ambient temperature change, zero shift of amplifier, the change of enlargement factor to the temperature survey. This article introduces the method of eliminating these influences and different input passageway consist of platinum resistance of three wire system, standard resistance, constant electric current supply and multi-channel switch. Microcontroller selecting from different input passageway sets the input capacity to the amplifier for amplifying. Voltage/frequency changer transforms the voltage signal to frequency signal. Microcontroller surveys the input capacity from every input passageway with the corresponding frequency signal. With the differnce/ratio method to eliminate the influence owing to thermal resistance connecting wire resistance as ambient temperature change, zero shift of amplifier, the change of enlargement factor to the temperature survey to achieve the object of upgrading thermometric instrument precision for platinum resistance.