Abstracts Engineering

Design criteria for DC link filters in a synchronous generator-phase controlled rectifier-filter-load system

by Gregory J. Greseth

Power electronics have advanced to the point that they can be considered for use in large, high power dc electrical distribution systems. The proposed Navy DC Zonal Electrical Distribution System (DC ZEDS) being designed for the new DD-21 utilizes a rectified ac generator output which is filtered and stepped to usable voltages by local dc-dc converters. One characteristic of the high bandwidth converters is a negative input impedance, which when coupled with an LC input filter, can lead to system instabilities. This thesis examines various stability criteria for determining parameters of the dc link filter. Comparisons between a simplified system model, a model using subsystem impedances and an Advanced Continuous Simulation Language (ACSL) model of a reduced order system are made. Simulations were conducted to verify the validity of the stability criteria. The ACSL model provides an extremely useful tool in evaluating the response of various system parameters to changes in design values. The design criteria examined in this thesis can be ultimately used to provide design specifications to future vendors.