Design of a Variable Speed Compressor Drive System for Air-Conditioner without Electrolytic Capacitor

This paper presents an electrolytic capacitor-less variable speed drive system for the compressor of an air-conditioner to enhance cost and size competitiveness and reliability. The electrolytic capacitor in the DC link of the inverter is replaced by a small film capacitor, whose capacitance is around a couple thousandth of the conventional drive system. Due to the small capacitance, not only the size of the DC link capacitor can be reduced, but also the initial charging circuit of the inverter can be saved. Furthermore, the total harmonic current of the AC source side can be reduced to one third of the conventional system. The effectiveness of the proposed system has been verified by several experimental results using a commercial air-conditioner with the modified inverter.