A Radially Symmetrical Star-shaped Core Multi-winding Transformer With Controllable Magnetic Integration for N-port MAB Converters

Dual active bridge (DAB) and multiple active bridge (MAB) converters are widely used in the on-board propulsion systems of transportation electrification applications. The tendency of power density improvement leads to the magnetic integration investigation of the isolated HF links, that is to integrate the series inductors and a high frequency transformer (HFT) into a single magnetic component by increasing the leakage inductance of the HFT. This paper proposed a novel radially symmetrical star-shaped core (RSSC) high frequency multi-winding transformer (HFMT) with split windings for the generalized N-port MAB converters. The proposed HFMT can adjust the leakage inductances within a wide range by the magnetic integration control parameters, which includes lengths of extension legs, side and central pillars, horizontal air gaps, turns of windings and winding distribution ratio. Port consistency is promised by the insertion of vertical flux barriers. Based on the magnetic circuit analysis, accuracy of leakage inductance estimation can be guaranteed. A cross-shaped-core HFMT is designed for a quadruple active bridge (QAB) to validate the effectiveness of the proposed RSSC HFMT as a case study. 3D Finite Element Analysis (FEA) simulation and prototype experiments were conducted to validate the theoretical analyses.