High-Power-Factor Quasi-Resonant Flyback Converters Draw Sinusoidal Input Current

This paper presents a novel control methodology that enables high-power-factor quasi-resonant flyback converters with peak current mode control to ideally draw a sinusoidal current from the input source, thus performing like boost converters operated in the same way. It is a well-known fact that the traditional quasi-resonant control methodology, used in a number of control chips commercially available, when applied to high-power-factor flyback converters provides an inherently distorted input current. Although the resulting distortion level is such that compliancy with IEC61000-3-2 regulation on the limits for harmonic current emissions can be easily achieved, recently this inherent distortion is becoming a problem in Solid-state Lighting (SSL), where this topology is extremely popular. In fact with the traditional method it is difficult to meet the Total Harmonic Distortion (THD) target (< 10% or even lower) that is becoming a market requirement in some geographical areas [1]-[3]. The novel control method aims to overcome this issue.