Signal flow graph nonlinear modeling method is employed to develop a unified model for the DC-DC parallel converter with coupled inductors. Derivation of large, small-signal and steady-state models from this unified signal flow graph is demonstrated. Converter performance expressions (steady-state and small-signal characteristic transfer functions) are derived. Large-signal model is developed and programmed in TUTSIM simulator. Large-signal responscs against load and supply disturbances are obtained. Furthermore, to validate the signal flow graph modelling, large-signal responses compared with PSIM simulator. The results closely matching with each other thus, validating the signal flow graph modelling.