H ∞ loop-shapingcontrol schemes for the buck converter and their evaluation using μ-analysis

Two H∞ loop-shaping control schemes for the buck converter are presented and compared to the existing linear quadratic scheme. The first control scheme is the H∞ loop-shaping controller, and the second scheme is the current-assisted H∞ loop-shaping. The evaluation of the proposed controllers is performed in terms of robust stability, control circuit complexity and robust performance of the converter. The powerful tool of μ-analysis is applied to examine the robust features of the buck converter, which employs any of the control schemes. It is shown that the current-assisted H∞ loop-shaping control scheme exhibits better performance than the other two control schemes. This conclusion is verified by simulated and experimental results.