Integrated Buck-Buck-Boost AC/DC Converter

Single-Stage transformerless AC/DC converter received much attention in the universal line application. Unlike the existing converters a new high step-down transformerless single-stage single-switch AC/DC converter is proposed. The topology integrates a buck-buck-boost converter with low intermediate bus and output voltage. The converter utilizes a buck converter as a PFC cell and buck-boost converter as a DC/DC cell. The buck-buck-boost converter is able to reduce the bus voltage below 150V under all input and output condition without using a step-down transformer. The absence of transformer reduces the component count, size and cost of the converter. Unlike the existing converter, buck-buck-boost is able to achieve simple control structure with single switch, positive output voltage and high power factor. By using DPT feature, converter is able to achieve high power conversion efficiency. The converter is successfully tested by using MATLAB/Simulink. The simulation result shows that the converter is good tradeoff between reduced bus voltage and high power factor.