engleski

Increasing accuracy of temperature measurement based on adaptive algorithm for microcontroller transmitter

The article compares the most common methods for converting measured resistance of platinum sensor to a temperature value in relation to the new adaptive algorithm applied in a compact temperature transmitter. The hardware of the temperature transducer is based on a microcontroller with input/output circuits that generate an output signal proportional to the measured temperature. The compact temperature transmitter has size constraints because it is required to be installed in the head of an industrial thermometer. The microcontroller is limited by the available power supply and memory resources. The platinum temperature sensors should conform to industry standards and fit a mathematical curve known as the Callendar-Van Dusen equation with nominal values of constants , and . The increase in the total accuracy of temperature measurement is possible by matching the sensor characteristics with the connected temperature transducer. After calibration of the platinum sensor, corresponding new constants are calculated and written into the temperature transmitter. The presented new software method enables the use of the Callendar-Van Dusen constants retaining or even increasing the accuracy of the resistance to temperature conversion.

adaptive algorithm; microcontroller; sensor; temperaturemeasuring; temperature transmitter

U članku su uspoređene najčešće metode pretvorbe izmjerenog otpora platinskog senzora u vrijednost temperature u odnosu na novi adaptivni algoritam u kompaktnom pretvorniku temperature. Hardverska osnova pretvornika temperature je mikroupravljač s ulazno-izlaznim sklopovima koji generiraju izlazni signal proporcionalan izmjerenoj temperaturi. Kompaktni pretvornik temperature ima dimenzijska ograničenja kako bi se mogao montirati u glavu industrijskog termometra, a mikroupravljač je ograničen glede raspoložive struje napajanja te memorijskih resursa. Platinski temperaturni senzori normirani su Callendar-Van Dusenovom jednadžbom s definiranim koeficijentima A, B i C. Povećanje ukupne točnosti mjerenja temperature moguće je usklađivanjem karakteristika senzora s pretvornikom temperature na koji se priključuje. Kalibracijom platinskog senzora odrede se pripadni koeficijenti CvD jednadžbe koji se mogu upisati u pretvornik temperature. Prikazana nova programska metoda omogućuje korištenje navedenih koeficijenata uz zadržanu ili čak i povećanu točnost pretvorbe otpora u temperaturu.