A high efficiency and high power factor offline converter for solid state street lighting applications

A high power factor, high efficiency offline driver for LED lighting applications is presented in this paper. Among all the suitable candidate topologies, a multiple stage structure has been chosen, to guarantee the greatest possible flexibility, thanks to the use of optimized topologies both on line side and on load side. Galvanic isolation is provided by means of an intermediate DC transformer stage. A comparison between two different implementations of the latter has been performed in order to better understand advantages and disadvantages of the two proposed topologies and find out an optimal configuration. Despite the presence of multi-stage conversion, a high (>;90%) overall efficiency is achieved. Analytical and experimental results are provided.