The realization of temperature controller for small resistance measurement system

This paper concerns the construction and experimental research of an automatic temperature control system for a system for measuring small resistance increments. After turning on the measuring system, the PCB with electronics was warming up and the long-term temperature drift caused a change in the measurement result. The aim of work was to reduce the time of transient state and reach the set temperature of the measuring system earlier, what makes it possible to perform faster measurements in steady state. The effect of temperatures above the nominal value on the measurement result and the resulting heating curve was also investigated. The system automatically warms up to about 32°C and has a time constant of approximately 1200 seconds. With the USART terminal on the PC and the NI USB-6341 data acquisition card, it is possible to easily record data (temperature and resistance) in digital form and their further processing and change of the set temperature value of the regulator. Examples of measurement results for several temperature values, along with temperature and time variations, are presented and compared to reference values. Identification of the object is done according to the Ziegler-Nichols method. The algorithm for determining the parameters of the step characteristics and examples of calculations of the settings of the controller are included with the example characteristics of the control object.

Key words: temperature control, thermostat, microcontroller, temperature sensor, Ziegler-Nichols tuning method.