This paper presents a systematic development of unified signal flow graph model for an interleaved buck converter system operating in continuous inductor current mode. From this signal flow graph small, large-signal and steady-state models are developed, which are useful to study the converter dynamic and steady-state behaviour. Converter performance expressions like steady-state voltage gain, efficiency expressions and other small-signal characteristic transfer functions are derived. Development of unified signal flow graph is explained for a 3-cell interleaved converter system. Derivation of large, small-signal and steady-state models from the unified signal flow graph is demonstrated by considering a 2-cell interleaved buck converter system. Large signal model was programmed in TUTSIM simulator, and the large-signal responses against supply, load disturbances were predicted. Signal flow graph analysis results are validated with PSIM simulations. Further, the mathematical models obtained from the signal flow graph modelling are in agreement with those obtained from the state-space averaging technique. Copyright (C) 2003 John Wiley Sons, Ltd.