Digital control of boost PFC AC/DC converters with low THD and fast dynamic response

This paper presents a digital control scheme for boost power-factor-correction (PFC) AC/DC converters to achieve both low total-harmonic-distortion (THD) and fast dynamic response under large load variations. Compared with conventional control methods, the proposed digital control scheme can achieve a lower THD by sensing the input line voltage for feed-forward compensation in current loop to eliminate disturbance coming from the input line voltage, this paper also proposes the off-time duty ratio control to reduce the input current distortion. A synchronous sampling technique based on the double-line frequency can improve the dynamic response of the output voltage. The proposed control scheme has been verified by using simulation software PSIM and realized by using a DSP TMS3202812 in applications to a 1400 W prototype of boost PFC AC/DC converter. Experimental results are given to illustrate the feasibility of the proposed control scheme.