Analytical Treatment of the Power Transfer Relationships for a Coupled, Current-Fed, Multi-Port Dual Active Bridge Converter

Abstract

Existing research has demonstrated that mutual inductors within the load ports of a Dual Active Bridge (DAB)-based converter enable fault tolerant operation. Similar research efforts with the DAB converter have also proven that incorporating a multi-winding transformer in the design can result in an interconnection of multiple DC buses with isolation and reduced switching losses. Therefore, a current-fed, multi-port DAB converter is proposed with the intention of capturing the benefits of both features. The performance of the proposed converter is evaluated against the traditional multi-port DAB. In particular, the potentially non-ideal square waveforms at load port voltages are mathematically described. The converter characteristic equations are then verified with PLECS simulations. Finally, the effects of inductor size on port voltages and power transfer are explored. The results of the analyses provide the conditions in which simplification to power flow equations for voltage-fed multi-port converters is applicable. v Table of Contents

Power Flow Control for Decoupled Load Performance of Current-Fed Triple Active Bridge Converter

“…The CFTAB converter developed in this paper takes the typical design of a TAB converter and adds mutual inductor pairs to the medium voltage windings of the three-winding transformer [21]. The topology of the converter is shown in Fig.…”

“…Table II provides the circuit design parameters for the CFTAB converter, as mentioned. These parameters are based on the design parameters of a previous analysis and are similar to analyses on other multi-port structures [13], [21]. One key feature to note is that the switching frequency of the design has been slowed down from 40kHz to 1kHz to account for performance restrictions within the TI controller and real-time digital simulator (discussed in Section V).…”

“…Also, by adding inductance to a converter, fault tolerant operation can be achieved [20]. If these features are combined, the result is a current-fed, multi-port converter that can interconnect multiple MVDC buses within a dc network [21]. See Fig.…”

“…The current-fed triple active bridge (CFTAB) converter design is the basis for the research performed in this article [21]. With emerging state-of-the-art magnetics enabling the design of transformers and inductors for solid-state transformers (SSTs), the previously theoretical coupled inductor design within the CFTAB converter become possible to implement within hardware.…”