Stability Analysis of a Constant Power Load Serviced by a Buck Converter as the Source Impedance Varies
Authors
Roth, George J
Subjects
Constant Power Load
Buck Converter
DCDC
Negative Impedance
Stability
Buck Converter
DCDC
Negative Impedance
Stability
Advisors
Julian, Alexander L.
Date of Issue
2012-09
Date
Sep-12
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
As the NAVY moves forward with plans to become less dependent on fossil fuels and more dependent on hybrid electric drives and all-electric ships, being aware of the stability issues associated with direct current (DC)-DC and DC-alternating current (AC) power converters and understanding how to solve the issues that come with using them, are very important. The negative input impedance that is observed when using a buck converter servicing a constant power load (CPL) is one of the issues that needs to be understood. Understanding the stability issue caused by the negative input impedance and mitigating this instability by varying the input source impedance is the focus of this thesis. Using a Simulink model of an ideal CPL, we determined the expected results. Then, the Simulink results were compared to the analysis of the linearized small signal transfer function to determine how well the results of the two matched. Finally, the hardware model was observed and its results compared to the Simulink model and linearized small signal transfer function. These experiments led to the conclusion that increasing the capacitance or decreasing the inductance reduces the input source impedance and, ultimately, reduces instability in the system.
Type
Thesis
Description
Series/Report No
Department
Electrical Engineering
Organization
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.