Modeling and Optimal Modulation of MAB Converter Using Full-Order Impedance Matrix

Multiactive-bridge (MAB) converter is gaining high interest as a multiport converter topology due to its multidirectional power flow capability, zero voltage switching, and galvanic isolation between ports with voltage step-up/down. One of the key components of the MAB converter is the high-frequency <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula>-port magnetic link. An <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n \times n$</tex-math></inline-formula> impedance matrix is a full order model to represent an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$n$</tex-math></inline-formula> -port passive network, without losing any information seen from the ports. In this work, a full-order impedance matrix-based model for an MAB converter is introduced, and a systematic approach is devised to find the optimal modulation parameters which minimize the converter losses. This approach is deployed to obtain desired power flow, minimize conduction losses, and analyze zero-voltage-switching (ZVS) conditions. A frequency domain model is developed which uses the impedance matrix to solve for the branch currents. The inductance matrix of the high-frequency ac link is further used with the frequency domain model to analyze the port ZVS conditions by investigating the inductive energy in the high frequency ac link. The work is experimentally verified on a GaN based four-port 250-W MAB converter with its ports rated at 200 V, 30 V, 16 V, and 8 V.