Time-varying effects and averaging issues in models for current-mode control

This paper investigates issues in modeling of current-mode control in converters. The effects of the current-sampling intrinsic to current-mode control are analyzed, and inadequately recognized limitations of linear time-invariant (LTI) models at high frequencies (where the system behavior is time-varying) are exposed. The paper also examines the geometric methods used to derive duty-ratio constraints in averaged models of current-mode control and points out the sources of discrepancies among various models. The conclusions are supported by simulation and experimental results.