Limitations of the Flyback Power Factor Corrector as a One-Stage Power Supply

Low cost passive power factor correction solutions and single-stage integrated converters cannot draw a sinusoidal input current and are only suitable solutions for low power levels. Power factor correctors (PFC) with a multiplier solve this drawback, but need a second-stage DC/DC converter to obtain fast output voltage dynamics. However, the output voltage response of a PFC can be improved by increasing the bandwidth of the error amplifier of the output voltage feedback loop. So, a one-stage PFC can be used as complete power supply when an extremely fast output response is not required. Nevertheless, increasing error amplifier bandwidth compromises design, making it more difficult to comply with IEC 61000-3-2 standards. This paper analyzes the application limits of the Flyback PFC as a complete power supply. The thrust of the paper is to establish the Flyback PFC as a solution for PFC topologies depending on power level, input voltage range, output voltage, output response and line current harmonic content. Static and dynamic models have been included in this study. Finally, theoretical results are validated using a 600 W prototype.