Design and Optimization of an Efficient (96.1%) and Compact (2 kW/dm3) Bidirectional Isolated Single-Phase Dual Active Bridge AC-DC Converter

• Main Author: Jordi Everts
• Format: Article
• Language: English
• Published: MDPI AG 2016-10-01
• Series: Energies
• Subjects: ac-dc power converters; battery chargers; dual active bridge; DAB; optimal design; power metal oxide semiconductor field effect transistors (MOSFETs); single-stage
• Online Access: http://www.mdpi.com/1996-1073/9/10/799

The growing attention on plug-in electric vehicles, and the associated high-performance demands, have initiated a development trend towards highly efficient and compact on-board battery chargers. These isolated ac-dc converters are most commonly realized using two conversion stages, combining a non-isolated power factor correction (PFC) rectifier with an isolated dc-dc converter.This, however, involves two loss stages and a relatively high component count, limiting the achievable efficiency and power density and resulting in high costs. In this paper, a single-stage converter approach is analyzed to realize a single-phase ac-dc converter, combining all functionalities into one conversion stage and thus enabling a cost-effective efficiency and power density increase. The converter topology consists of a quasi-lossless synchronous rectifier followed by an isolated dual active bridge (DAB) dc-dc converter, putting a small filter capacitor in between. To show the performance potential of this bidirectional, isolated ac-dc converter, a comprehensive design procedure and multi-objective optimization with respect to efficiency and power density is presented, using detailed loss and volume models. The models and procedures are verified by a 3.7kW hardware demonstrator, interfacing a 400Vdc-bus with the single-phase 230V,50Hz utility grid. Measurement results indicate a state-of-the-art efficiency of 96.1% and power density of 2 kW/dm3, confirming the competitiveness of the investigated single-stage DAB ac-dc converter.