Comparative analysis and validation of different modulation strategies for a dual active bridge converter

Abstract

This paper presents a comparative analysis of different modulation techniques that can be applied to a dual active bridge (DAB) converter, validating and analyzing its performance with the realization of computational simulations. A DAB converter is an isolated dc-dc topology with great applicability in the most diverse branches of power electronics, as is the case of energy storage systems, solid state transformers, power electronic traction transformers, and, more recently, dc or hybrid microgrids. In this sense, several strategies have been studied to mitigate circulating currents, expand the zero voltage switching operating range, and reduce reactive power, as well as semiconductor stress. One of the possible solutions to increase the efficiency of this dc-dc converter is to adopt specific modulation techniques, however, it is necessary to assess which one has a better cost-benefit ratio. Thus, this paper presents a comparative analysis between: (i) Duty-cycle modulation; (ii) Single phase shift (SPS); (iii) Dual phase shift (DPS); (iv) Extended phase shift (EPS); (v) Triple phase shift (TPS). Specifically, this comparative analysis aims to investigate the performance of a DAB converter when controlled by the aforementioned strategies and operating with a nominal power of 3.6 kW, a switching frequency of 100 kHz, and a transformation ratio of 2:1. Considering these operation parameters and by analyzing the obtained simulation results, it was shown that only SPS, DPS, and TPS modulation techniques are considered suitable for this particular case. Duty-cycle modulation presents time limitations during the power transfer, whilst EPS is more suitable for dynamic medium/high power applications since it is capable of transferring a certain power value in a short period of time.