Analysis of quasi-Z source PFC convertor and its comparison with traditional flyback

Abstract

The quasi Z-source power factor correction (QZS-PFC) in the range of 36–720W is analyzed for continuous conduction mode operation and compared with a classical flyback power factor correction (F-PFC) under the same operation conditions. A very precise closed loop duty ratio control was developed to optimize the performance of the QZS-PFC. The selected topology of QZS-PFC is compared with traditional F-PFC operating in continuous conduction mode (CCM) and the study confirms that it operates better than the F-PFC at different power ratings. The major advantage of QZS-PFC is its high performance, and ability to accommodate higher load than the traditional F-PFC. The total harmonic distortion (THD) for the QZS-PFC was considerably low when load were increasing; the value for the THD% reached the standardized limits of 5% while operation at load of 360 W and above. Moreover, the power factor value is close to one across the range of operation with minimal voltage and current ripple. It was confirmed that the main elements of QZS-PFC has lower current and voltage stress due to the effect of crossed capacitors. In contrast, F-PFC suffers from high voltage spikes and requires a snubber circuit. Considering the obtained results, the QZS-PFC has a better operation range which makes it an interesting topology to be widely explored.