Sensorless temperature control of household refrigerators based on the electric current of the compressor

Abstract

The present study is aimed at putting forward a novel temperature controller (including software and hardware) for a fan-and-damper refrigerator considering the electric current drawn by the single-speed compressor as the process variable. The control algorithm consists in a dynamic reference modification of a PI controller, together with a set of empirical conjectures. In addition, a purpose-built electronic board was designed and prototyped. All experiments were performed in-house with the refrigerator placed in a climate chamber. The refrigerator was tested at two different surrounding air temperatures (16 and 25 °C) under pulldown, defrost recovery, and variable ambient temperature regimes. It was noted that the proposed controller was able to maintain the refrigerator temperature within ±1 °C tolerance bounds – figures like those obtained for the baseline thermistor-based temperature controller – albeit being less costly.