Modeling and practical design issues for average current control

Abstract

This paper addresses modeling and practical design issues for PWM converters with average current control. A straight-forward averaged modeling method is proposed, and the resulting models are shown to be accurate enough for practical design purpose. Limitations of previously published models that incorporate sampling effect are discussed. The proposed averaged model is then applied for stability analysis and control design. In particular, conditions under which switching instability may occur are identified, and design method that avoids the instability problem is presented. The proposed modeling and design methods are demonstrated and further validated by a prototype synchronous-switch buck converter with 5 V input and 2 V output.