Modeling, analysis, and design of the quasi-average current-mode control

A current-mode control technique, quasi-average-current-mode control (QACC), is studied for DC/DC power convertors. A small-signal model is developed for QACC. The model is derived for converters operating in the continuous conduction mode. It is accurate up to half of the switching frequency. The proposed small-signal model is used to assess the dynamics of PWM converters with QACC, and to compare its performance to the current-inject control (CIC) and charge control (CC) schemes. As in CC, the QACC converges to CIC at light loads close to the boundary between continuous and discontinuous conduction modes. The dynamics of converters with QACC or CC are more sensitive to load change and less sensitive to line change than converters with CIC, especially the current loop dynamics.<
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