Optimum Design of a Multiple-Active-Bridge DC–DC Converter for Smart Transformer

The modular smart transformer (ST) is composed by several basic converters rated for lower voltage and power. In this paper, the quadruple active bridge (QAB) is used as the basic block for the modular ST. In this application, the efficiency and cost are the most important design parameters. Therefore, the paper focus on the design of the converter, with the aim to optimize its efficiency, taking the cost into consideration. To do so, the losses of all components are carefully modeled and a computer-aided design is used, where an algorithm to calculate the losses and cost is developed, allowing to perform multiobjective optimization. Additionally, silicon IGBTs and silicon carbide mosfets are considered for the design and the performance of the converter using both semiconductors technology is compared. Experimental results obtained for the optimized 20 kW QAB converter has shown an efficiency of 97.5%.

I. Introduction

Over the past years, many researches have been focused on efficiency improvement of dc–dc converters and several design optimization methods and power converter topologies have been discussed [1]– [9]. Among the most investigated topologies, the dual active bridge (DAB) converter [10], composed of two active bridges connected through a high frequency transformer, is highlighted as a high performance solution, because of its soft-switching feature and high power density. Therefore, this converter has been widely used in application with different power and voltage levels, mainly those that required high efficiency.