Research On Forward Converters With Inherent Demagnetizing Features

Forward converters have been widely used in aerospace power systems, telecommunicationenergy systems, welding machines, computer power supply and many other industry fields, due totheir high reliability and high efficiency. Transformer reset is a special issue for forward converters.With different transformer demagnetizing schemes, many forward converters have been proposed.Forward converters with inherent demagnetizing features are the forward converters in which diodesare used to construct magnetic reset paths. And in these forward converters, transformers aredemagnetized automatically. This paper makes a systematic study of forward converter with inherentdemagnetizing features with ‘basic switching cells’ method.First of all, this paper analyzes the forward basic cells based on the ‘basic switching cells’topology composition method, and the methods of generating forward converters by the basic cells.And then, a class of forward converters with inherent demagnetizing features is proposed based onthem. Thses topologies include the ones which are generated by the forward positive cell (FPC) andthe forward negative cell (FNC) and proposed in the previous literatures, and also include the newones which are generated by the forward composite cell (FCC) and have not been verified. And then,the forward converters generated by the single FCC and the ones generated by the three basic cells areselected to research and analyze, and the prototypes for each converter are developed. Theoreticalanalysis and experimental results verify the validity of the new topologies and the thinking ofgenerating forward converter by the three basic cells.Finally, the thinking of integrating transformers is used to solve the shortcomings, which are onedirection magnetization of transformer, low utilization rate of the core, and low power density. Thispaper takes the interleaved series input parallel output forward converter as example, and the twotransformers in this converter are integrated to optimize the topology to solve the above shortcomings.Its working principle and characteristics are analyzed detailed and a prototype is built to verify theanalysis.