Doctoral Dissertations


Sara Yazdani


“This research is an endeavor to apply new and well-established control methodologies to improve transient response, stability and reliability of three-phase inverters in grid-connected and isolated mode of operation. In the course of studying the effect of these methodologies, model-based control is introduced and is extensively applied which is relatively a new approach. In addition, the application of this concept has been studied on developing “grid-forming” controls to allow wind and solar inverters to support voltage and frequency levels like traditional generators.

This research encloses the details of three major works of this research and their possible contributions on improving the performance of three-phase inverters in gridconnected and isolated mode of operation. The first one employs the concept of adaptive control using multiple models and a hierarchical control approach to smoothly switch between isolated and grid-connected modes of operation. In the second work, the features of the first research work have been applied and more nourished to control a "grid-forming" unit. The interactions of this grid-supporting converter with a "grid- forming" unit is the main subject of discussion in this work. The last work applies the concept of internal-model control to introduce a new control methodology in power-synchronization method. This approach has tackled the non-minimum phase issue attributed to power-synchronization methodology and offers a robust solution.

Furthermore, in this research, detailed stability analysis of all the proposed control structures have been presented. Along with all simulation verification, FPGA-Based Hardware-in-the-Loop (HIL) has been utilized to verify the performance of the discrete control structure.

The details of plant modeling, controller design, HIL and experimental results are presented for all of the proposed schemes in each section”--Abstract, page iv.


Ferdowsi, Mehdi

Committee Member(s)

Sarangapani, Jagannathan, 1965-
Kimball, Jonathan W.
Shamsi, Pourya
Rownaghi, Ali A.


Electrical and Computer Engineering

Degree Name

Ph. D. in Electrical Engineering


Missouri University of Science and Technology

Publication Date

Summer 2020

Journal article titles appearing in thesis/dissertation

  • Internal Model Based Smooth Transition of a Three-Phase Inverter Between Islanded and Grid-Connected Modes
  • Advanced Current-Limiting and Power-Sharing Control in a PV-Based Grid-Forming Inverter Under Unbalanced Grid Conditions
  • Internal Model Power Synchronization Control of a PV-Based Voltage Source Converter in Weak-Grid and Islanded Conditions


xiv, 115 pages

Note about bibliography

Includes bibliographic references.


© 2020 Sara Yazdani, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 11762

Electronic OCLC #