Transient performance improvement for digital control boost power factor correction converters

This paper deals with specific problems encountered when full digital control is applied for the boost-type power factor correction (PFC) converter. The robust performance, voltage regulation and sample frequency of the proposed controller are highlighted. Compared with traditional design, a novel input voltage feed-forward control algorithm is proposed to reduce the closed-loop time constant and output voltage overshoot/drop, which omits a second-order low-pass filter. By synchronizing output voltage sampling frequency with the zero-crossing of line voltage, which can be executed easily in digital processor, the twice-line-frequency ripple component can be removed from the measured output voltage. Therefore, dynamic characteristics of the converter can be improved greatly. Simulation results indicate that the proposed methods not only reduce the computation time but also improve the transient response.