A microcontroller-based soft-starter for residential air-conditioners: harmonic analysis

• Published in: Compel Vol. 27; no. 5; pp. 1081 - 1097
• Main Authors: El Ferik, S., Ahmed, C.B., Ben Amor, L., Hussain, S.A.
• Format: Journal Article
• Language: English
• Published: Bradford Emerald Group Publishing Limited 01.01.2008
• Subjects: Control algorithms; Controllers; Electric currents; Electrical equipment; Energy conservation; Energy consumption; Load; Microelectronics; Payback periods; Studies; Waveform analysis; Microcontrollers; Electric machines; Wave properties; Electric current; Electric motors
• ISSN: 0332-1649; 2054-5606
• DOI: 10.1108/03321640810890780

Purpose - The purpose of this paper is to reduce the inrush current and dip in voltage for energy- saving purposes in relation to residential air-conditioning systems.Design methodology approach - The paper focuses on the experimental harmonic investigation of a window-type residential AC unit line current under time-based soft-starting control strategy. The control strategy assumes that only source voltage and current measurements are available. The soft-starter is based on power electronic devices controlled through a firing signal generated by a programmed microcontroller during the first 500 ms.Findings - The harmonic content shows the effect of the soft-starter in exciting high-frequency components of the line current. Harmonics investigations show that the high frequencies - even or odd multiples - of the fundamental line frequency are all excited by the soft-starter approach. Some of these frequencies may harm the life cycle of the air-conditioner.Research limitations implications - The real data harmonic analysis shows that the adopted approach excites the entire frequency spectrum of the signal. A better monitoring of the harmonics is required. A closed loop adaptive soft-starting control may perform much better than a time-based soft-starting strategy.Originality value - The paper assesses the power quality related to time-based soft-starting strategy of a residential air-conditioning system to reduce the inrush current and the dip in voltage, both with a serious effect on energy savings, especially when the AC load is around 65 per cent of the total power demand load.