Modular DC/DC converter structure with multiple power flow paths for smart transformer applications

Abstract

Smart Transformers (ST), solid-state transformers with advanced control functionalities, are expected to have an important market by 2020. However, still important technological barriers, in terms of reliability and efficiency, exist and only new semiconductor devices cannot solve them. The use of advanced power converter topologies and architectures can play a role too. In this paper, a particular structure for the isolated DC/DC converter, core of a typical three-stage ST, is investigated. By employing the concept of Multiple Active Bridge, a modular and redundant architecture, a power converter characterized by multiple power routing paths is investigated.

Quad-Active-Bridge DC–DC Converter as Cross-Link for Medium-Voltage Modular Inverters

“…Therefore, it is found the equation of ∆P b in function of ∆D 2 , as presented in (25). The same procedure can be applied to the power transferred by the cell c and the results is given by (26). As can be observed in (25) and (26), the equations of the additional power are in function of ∆D 2 .…”

“…The same procedure can be applied to the power transferred by the cell c and the results is given by (26). As can be observed in (25) and (26), the equations of the additional power are in function of ∆D 2 . This variable can be used to control the additional power transferred to the MV bridges.…”

“…The control scheme used in this converter has the same concept of the structure described in detail in [26], but it was adapted for the TCM. Fig.…”

“…Therefore, the duty-cycle of each bridge is composed by two variables: d 2 , responsible to ensure ZCS condition, and ∆d k (where k = b, c, d), responsible to balance the power. The correlation between the variable ∆d k and the amount of additional transferred power to each MV bridge is presented in (25) and (26).…”

Smart Transformer reliability and efficiency through modularity

“…In terms of power routing capability, the DAB is limited to voltage sharing as well and requires many cells. The QAB is the most complex solution, which is least investigated in literature, but provides multiple possible power flow paths [15]. It requires fewer magnetic cores in comparison to the DAB, whereby the core design is more difficult to optimize.…”