Zero-ripple analysis methods for three-port bidirectional integrated magnetic Ćuk converters

In this paper, the three-port Ćuk converter interfaces one unidirectional input power port (envisioned to be a DC power source such as PV, or fuel cell) and two bidirectional output ports, representing the grid-tied inverter dc bus and a storage port respectively, and combines all the magnetics into a single core. The well-known property of the basic Ćuk converter that emulates an ideal dc-dc transformer (zero ripple terminal currents) is extended to three ports and is analyzed in detail. Two methods, one involving the physical structure of the core, and the other, a circuit-based dual approach, which is directly related to the core structure, are applied to solve the zero-ripple problem, and the accuracy of one of them over the other is verified with simulation results. Three different power transfer modes in this three-port converter are compared using the two methods mentioned above.