Means of eliminating electrolytic capacitor as the energy storage component in the single phase AD/DC two-stage converter

摘要

A power factor correction (PFC) circuit includes an inductor, a diode, a storage capacitor, a switch and a control unit. The input power has a voltage fluctuation V₁. The storage component absorbs a first voltage fluctuation and a switch regulation circuit absorbs a second voltage fluctuation V₂. Thus output voltage from the PFC circuit is not a conventional constant voltage but a voltage of a great ripple. The PFC circuit further has a harmonic regulation unit. The harmonic regulation unit generates a voltage signal containing 3^rd harmonic. The control unit receives a feedback signal and the voltage signal containing 3^rd harmonic to generate a reference to the inductor current. Therefore, the inductor current contains 3^rd harmonic. Thus power fluctuation absorbed and released by the capacitor is smaller. As a result energy storage capacitance can be reduced significantly.