Design of Modular Converters; Survey and Introduction to Generic Approaches

This paper presents a new approach based on converter networks using elementary cells (ec). It deals with the beginning of research and development carried out on the design of the "ec", the random command and the magnetic coupling among the elementary cells. This paper introduces at first the recent works carried out on interleaved "ec" and power electronics converters (cvs) into networks: from basic interleaving approaches, trying to minimize filter sizes up to highly coupled solutions trying to optimize sizes but also current and voltage levels. In the next sections of the paper, the modular approach will be presented. The paper presents a study showing how a random mode control is used to simplify the implementation of a generic "ec" into any network. Evaluating the output voltage filtering criteria, we compare classical synchronous interleaved and random mode controls. Then, the paper focuses on the design and the characterization of the elementary cell and especially on its active part. The last part of the paper focuses on magnetic coupling for converter coupling and filtering. Experimental results underline the importance of coupling among elementary cells and inside the corresponding "cvs" and an analytical study of magnetic coupling is presented. An 2n-windings transformer formed of n identical three-winding transformers is used to connect the "ec" among them. The aims of these studies are to improve electrical management of modular "cvs" network without any constraints on the modularity and the genericity of the approach.