Hybrid Digital Adaptive Control for Synchronous Buck DC-DC Converters

This paper presents a hybrid digital adaptive (HDA) controller for synchronous buck DC-DC converters. The proposed controller is a combination of a standard constant-frequency PWM control in the vicinity of steady state and a bank of linear switching surface controllers (SSC) with slopes adaptively selected by a supervisor away from the reference. The supervisor selects the appropriate switching surface slope based on the capacitor current estimate and the quantized output error. A stability analysis using Lyapunov functions is presented. Experimental results for a 1.3 V, 10 A synchronous buck converter demonstrate near time optimal responses for a wide range of step load transients.