Single-Stage Single-Switch High-Power-Factor Boost-Forward Converter with FM and PWM Composite Control

This paper presents the single-stage boost-forward converter with pulse-width modulation and frequency modulation composite control. The feature of this composite control is the ripple of output voltage can be reduced by pulse-width modulation and the harmonic of input current can also be reduced by frequency modulation. Therefore, the higher efficiency of system is achieved. In this way, the pulse-width and frequency modulation are mainly controlled by the feedback voltage and the larger variation of duty-cycle would be improved when input current is changed and input voltage is dropped to low voltage level. In result, the ripple of output voltage and the harmonic of input current would be reduced. The experiment is carried out to verify this composite control method by compare to the single-stage high-power-factor boost-forward converter with single modulation control.