Stability Analysis and Design of DC-DC Converters With Input Filter

Abstract

At the point when an Input filter is added to the converter it decreases the electromagnetic Interference (EMI) of power input of converter and enhances the performance of load. Electromagnetic Interference (EMI) is disturbance because of either electromagnetic induction or electromagnetic radiation discharged from outside source that influence the electrical circuit. The EMI may interfere with or decrease the performance of the electrical circuit. Thus an input filter is for the most part used to lessen the electromagnetic interference in power source side of a converter. The Input filter added to converter to diminish the electromagnetic interference may change the system transfer function, which may bring about instability and influence the performance of the converter. In this way, input filter ought to be such that it will diminish the electromagnetic interference and it ought not to influence the performance and the stability of the system.Different stability criteria are considered in this undertaking to outline an input filter without influencing the performance and the stability of the system. One such criterion is Middlebrook's stability criterion which is chiefly utilized for designing input filter for DC-DC converters. The Middlebrook Criterion was at first proposed to investigate how the stability of a feedback-controlled switching converter is influenced by the addition of an input filter. Its objective is to ensure stability of the system, as well as to guarantee that converter dynamics are not changed by the presence of an input filter. The Middlebrook Criterion gives a basic designoriented sufficient stability condition imposing a small-gain condition on the minor loop gain. In this thesis the design of input filter for various converters using Middlebrook Criterion is studied.