One-cycle control is a nonlinear control method. The flow-graph modeling technique is employed to study the large-signal and small-signal dynamic behavior of one-cycle controlled switching converters. Systematic design method for one-cycle control systems is provided with the Ćuk converter as an example. Physical insight is given which explains how one-cycle control achieves instant control without infinite loop gain. Experimental results demonstrate that a Ćuk converter with one-cycle control reflects the power source perturbation in one-cycle and the average of the diode voltage follows the control reference in one cycle