Stability Analysis of a DC-link with Nonlinear Load - An Overview

This paper studies the stability of a dc-link when supplying a nonlinear load through a power converter. The dc-link often comprises an LC filter, which is subject to oscillation. The nonlinear behavior of the load reduces the damping of the system and may result in an unstable operation and system failure. This paper reviews the major modeling and active stabilization methods. It shows the shortcomings of the common assumption of constant-power load, namely, it fails to predict the practical stability limits and leads to an over-conservative design. A more realistic and systematic approach, based on the small-signal model of the system, is presented and analyzed. A comprehensive review of active stabilization methods is presented. Numerical simulation is used to validate the theoretical concepts.