A single-phase buck-boost AC-to-DC converter with high-quality input and output waveforms

This paper describes a new single-phase buck-boost power factor correction (PFC) converter with output-voltage-ripple-free operation. The rectifier is operated by two modulators which obtain PFC and the ripple-free operation, respectively. The modulator controls the buck-boost switch to obtain PFC. On the other hand, another modulator controls squire-value of instantaneous-inductor-current to perform the ripple-free operation. In both modulation, space or time-integral-value of the input and output currents in each modulation period is controlled directly and indirectly, respectively. Thus, modulation errors or distortions of the currents are eliminated even if the DC-inductor-current produces large ripples. The theories and combination technique of the modulators, implementation and experimental results are shown