Small-signal modelling of an average-current mode control is proposed. To analyse the characteristics of the control scheme, a continuous-time small-signal model is derived. The derivation comes mainly from the analysis of the sampling effect present in the current control loop. By using the mathematical interpretation of a practical sampler representing the sampling effect of a current control loop, the small-signal model of an average-current mode control can be derived. To show the usefulness of the proposed model both simulation and experiment are carried out. The results show that the predicted results by the proposed model are in much better agreement with the measured ones than those of the conventional model, even though a high gain of the compensation network of the current control loop is employed.