A new very simple control circuitry for the Flyback family of Power Factor Correctors operating in continuous conduction mode

This paper deals with a new control method for power factor correctors based on flybackpsilas family converters (e.g., Buck-Boost, Flyback, SEPIC, Cuk and Zeta). The control is carried out by a standard IC controller for peak current-mode dc-dc converters, with only an exponential compensation ramp and a peak detector. Neither analog multiplier nor input voltage sensor are needed to achieve quasi-sinusoidal line waveforms, which makes this control strategy very attractive. The method is similar the one-cycle control, but it does not need the use of either two matched integrators or a current sensor with an integrator with reset. Moreover, the line current is cycle-by-cycle controlled and, therefore, the input current feedback loop is extremely fast, which allows the use of this type of control with high frequency lines.