Flyback-based PFC converter with sinusoidal output for use in AC UPS

Abstract

Nowadays, the number of sensitive loads connected to the utility line increases fast. These loads need a highly reliable power supply. One way to provide this kind of energy is using an uninterruptible power supply (UPS). Basically, a UPS providing input power factor correction (PFC) is a three stage system: PFC stage, DC-DC converter stage and inverter stage. The approach proposed eliminates the DC-DC converter stage and removes the bulk capacitor of the PFC stage to use the natural output waveform of the converter before filtering: a semisinusoidal waveform. This allows the inverter stage working at low frequency with high efficiency. The PFC stage is based on a flyback topology operating in DCM to have a simple control loop.