Universal input voltage AC/DC converter with low output voltage and compliance with IEC-1000-3-2

Many one-stage solutions have been proposed in AC/DC converters to comply with the IEC 1000-3-2 Standard. However, when the converter must operate with universal input voltage (85 V - 264 V), a one step approach causes a large variation of the voltage across the secondary winding of the transformer, thereby complicating the possibility of using self-driven synchronous rectification. Moreover, a boost converter is usually used as a front-end stage and therefore, the intermediate DC bus voltage is usually around 400 V. In this paper a new approach is proposed using a buck converter as a front-end stage and therefore reducing the DC bus voltage. The input current is not sinusoidal but it complies with IEC 1000-3-2 regulations. A prototype of the converter has been built and the most significant experimental results are presented