DC Environment for a Refrigerator With Variable Speed Compressor; Power Consumption Profile and Performance Comparison

DC power distribution in residential sector has regained interest among researchers and industrial players as new electronics-based appliances became locally available. However, the compatibility of appliances with DC distribution systems still requires much research effort. This work mainly explores on the power consumption profile of an inverter-driven Variable Speed Controller (VSC-based) refrigerator that has not yet been analyzed as one of the most important household loads. This paper compares the power consumption in two scenarios; 1) using three supply configurations for a VSC-based refrigerator, a Battery-Inverter-Load, a Battery-Load and Grid-Load, and 2) using a same AC power source to supply a VSC-based refrigerator and a same-size conventional refrigerator. This analysis helps toward modeling and energy estimation of PV system applications involving storage batteries. A wireless monitoring circuit has been employed to handle temperature, current and voltage measurements with a high sampling rate to cover the potential surge power. The experimental measurements show a better performance on using DC over AC power source and the power rate consumed has a smooth pattern at the starting-on time until approach a rated power. The measured efficiency of the Battery-Load topology approaches 99% compared to that of the Battery-inverter-load topology, which is approximately 78.5%. It is also found that the tested refrigerator with Battery-Load topology consumes an energy amounting to 1.850 kWh daily, while with Battery-inverter-load topology consumes 2.466 kWh daily under the same operating conditions. These results can serve as a model for modeling refrigerators and other appliances that adopt speed controller technology to drive their motors.