Single-phase PFC control using PWM-based multipliers

This paper presents a control design for single-phase power-factor-correction (PFC) converters using PWM-based multipliers. Multiplication between the input voltage and the output voltage compensator output is usually required for generating a reference for the input current in single-phase PFC control. Conventional PFC control ICs use linear multiplier circuits that have very limited operation range and are sensitive to noise. The proposed multiplier design converts the sensed input voltage into a constant-frequency pulse-width modulated (PWM) signal. The voltage compensator output is then integrated by an integrator with a reset switch controlled by the PWM signal, producing a sampled-data output which is proportional to the required multiplication of the two signals. The method can be applied to different PFC control methods and provides a more cost-effective implementation than digital control. The proposed design is demonstrated on a 500 W dual-boost single-phase PFC converter using nonlinear average current control.