Search

A three-phase dual-active-bridge (3p-DAB) converter is an attractive topology for bidirectional power conversion in high-power applications. However, conduction and switching losses are two main loss mechanisms that severely affect its efficiency performance, and adoption of any single modulation scheme or topology cannot minimize these losses over a wide operating range. For this purpose, a reconfigurable topology of the 3p-DAB converter is proposed in this article that utilizes a reconfigurable and tunable resonant network to offer multiple degrees of freedom in minimizing conduction and switching losses over a wide range of operating conditions. The converter is designed such that for 40–100% of the rated output power, it operates as a tunable 3p-DAB resonant immittance converter with its output power controlled by varying switching frequency and tuning the resonant frequency of a resonant immittance network to track the switching frequency. Below 40% of the rated output power, the converter transforms to a tunable 3p-DAB series-resonant converter with its output power controlled by varying the impedance of a series-resonant network while keeping the switching frequency and phase shift constant. The combination of both operation modes jointly leads to wide-range zero circulating current and soft switching of all the switches and, hence, a wide-range high-efficiency performance, as validated by the experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes a fifth-order resonant immittance network based dual-active-bridge (DAB) converter and an optimal modulation method that will ensure high-efficiency operation of the converter under wide-range variations in voltage ratio and output power level. The proposed modulation method is based on the concept of total power loss minimization, where a loss model is developed and an optimization algorithm is formulated to compute the optimal set of internal and external phase shift parameters that will lead to the maximum efficiency for a given set of operating parameters including voltage ratio and output power level. It is found that to maintain high-efficiency operation under wide-range variations in voltage ratio and output power level, the DAB converter is required to switch between different operation modes and neither soft-switching operation nor unity-power-factor operation is able to achieve wide-range high efficiency performance when used alone. The importance of $reconfigurability$ of operation mode for achieving wide-range high efficiency performance is clearly illustrated in this paper. [ABSTRACT FROM AUTHOR]