A Novel Feedforward Stabilizing Technique to Damp Power Oscillations Caused by DC–DC Converters Fed From a DC Bus

Abstract

Switched-mode power electronic converters with feedback control tend to behave like Constant Power Loads (CPLs). When a CPL interacts with a poorly damped input LC filter, it amplifies any disturbance that occurs in the LC circuit, and the system becomes prone to instability. If the CPL is emulated as a positive resistance during any disturbance by manipulating the power that it consumes instantaneously, then the instability can be avoided. In this paper, this has been achieved by a feedforward technique, in which the power consumed by the CPL is made to follow the trajectory of the input voltage during any disturbance similar to the power consumed by a resistive load. The proposed feedforward technique has only one variable that can be determined by the input filter parameters and is independent of the type of the CPL. A case of a dc-dc converter-based CPL is studied in this paper, and the proposed technique is shown to create a virtual RC impedance at the input of the CPL to offset the negative resistance behavior. The effectiveness of the proposed technique is showcased through the detailed simulations and experimental studies on a 100-W CPL prototype.