Digital I2 average current mode control for swith-mode power supplies

I² average current mode control is a promising control technique featuring fast dynamic response, cycle-by-cycle current limiting and accurate current control. By implementing this technique digitally, the number of control loops is reduced, and the complexity of the loop design is simplified. In this paper, the digital control law, which only requires sampling the inductor current once in a cycle, is analyzed in detail. In addition, a small-signal model for this control technique is proposed. Simulation results show that it has a faster transient response than average current mode control while keeping zero DC current error. Experimental results demonstrate the characteristics of this digital implementation of I2 average current mode control and verify the accuracy of the proposed small-signal model.