Jacob David Gudex
PhD Graduate, 2025
Dissertation: TOWARDS AN IMPROVED UNDERSTANDING OF SHIPBOARD ELECTRICAL
POWER DISTRIBUTION SYSTEMS SURVIVABILITY: A METHODOLOGY AND METRICS FOR EARLY DESIGN PHASE EXPLORATION
M.S., Electrical Engineering, University of Wisconsin-Milwaukee, 2019
B.S., Electrical Engineering, University of Wisconsin-Milwaukee, 2017
Senior Systems Engineer
Leonardo DRS
Mark Vygoder
PhD Graduate, 2025
Dissertation: DESIGN, IMPLEMENTATION AND ASSESSMENT OF NANOGRID BUILDING BLOCKS FOR ENERGY SECURE ELECTRICAL DISTRIBUTION SYSTEMS
Abstract: This work presents zonal nanogrid building blocks (ZNBB) to enable a modular, scalable, cost-effective, and resilient solution to create energy-secure electrical power systems (EPS). The concept of ZNBB adapts zonal electrical distribution systems (ZEDS) from electrified shipboard power systems. ZNBBs can operate as separate islands within larger systems or can share power/energy if an electrical failure occurs within a ZNBB. This additional level of survivability is enabled through interzonal power sharing enabled by a novel distributed nanogrid controller for ZNBBs. The distributed controller used a pre-programmed state machine-driven events to coordinate power conversion and power distribution equipment to execute power routing when a zone experiences a loss of genset failure. The case study sets up the ZNBB in a three-zone system connected through an MVac ring bus. The distributed controller is validated through real-time controller hardware-in-the-loop (CHiL) simulation where Typhoon-HiL emulated the three-zone system and the distributed controllers are implemented in a National Instruments (NI) real-time controller. OPC UA (open platform communication unified architecture) is used for communication between the NI and Typhoon-HiL. Detailed simulation results are presented of the system transitions, synchronization events, switchgear and control actuation, and coordination during the loss of genset scenario. In addition, this thesis develops an integration framework to help bridge the gap between system-level metrics at the stakeholder level with low-level metrics at the equipment/subsystem through the adaptation of INCOSE (International Council on Systems Engineering) technical measures. This integration framework serves as a meta-level framework to help design and assess microgrid-based solutions for energy security. A microgrid protection design process is also introduced and validated through CHiL simulation based on a case study of a microgrid with parallel feeders. This protection design process provides a systematic process for designing and testing protection settings of power distribution equipment and ride-through setting for power conversion equipment. This process can be applied to the three-zone system and can be accessed through the integration framework. Lastly, this thesis provides simulation results of a digital twin of a BESS within a ZNBB to improve recovery under an electrical fault and loss of communications scenario.
M.S., Electrical Engineering, University of Wisconsin-Milwaukee, 2020
B.S., Electrical Engineering and Physics, University of Wisconsin-Milwaukee, 2017
Senior Systems Analyst
Leonardo DRS
Tianchan (James) Li
PhD Graduate, 2022
Dissertation: MODELING AND VALIDATION OF COMMON-MODE EMISSION IN SILICON
CARBIDE BASED VOLTAGE SOURCE CONVERTERS
Abstract: Electromagnetic compatibility (EMC) issues have become one of the most difficult challenges in power converter designs. With the invention of wide bandgap (WBG) power semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) power MOSFETs, the power converter designs are provided with the potential to be significantly more power dense than older generation converters using silicone IGBTs. However, the majority of spectral contents of the switching waveforms are moved from the verylow-frequency (VLF, 3 kHz to 30 kHz) range to low-frequency and up to the very-highfrequency (VHF, 30 MHz to 300 MHz) range. Moreover, due to the design traits of WBGbased converters, common-mode (CM) emission dominates the EMC problems. Conventional electromagnetic interference (EMI) modeling methodologies in the frequency range in and above VHF were mostly developed for applications where the power level is relatively low. For high-power and highly power-dense applications, new EMI modeling methodologies, especially in CM, need to be developed to allow more accurate analysis, more efficient design processes, and more optimal designs. This doctoral dissertation documents the author’s development of a novel CM emission modeling methodology with a set of CM model segments that form canonical SiCbased voltage source converters and the surrounding electrical environment, such as filter structures. The accuracy of all these model segments is validated with two applicational scenarios at frequencies up to 30 MHz. These modulized building blocks and the methodology using these blocks to construct full converter system CM models are lightweight and insightful, thus enabling more optimal design processes for SiC-enabled high-voltage and high-power density converters such as virtual prototyping processes and multi-objective optimization. Furthermore, the discoveries of this dissertation will help power electronics designers to understand better the potential and challenges of the utilization of SiC semiconductors in voltage source converters.
M.S., Electrical Engineering, University of Kansas, 2013
B.S., Electrical Engineering, Jiangsu University of Science and Technology, 2010
Postdoctoral Researcher
University of Wisconsin-Milwaukee CSEES
Seyed Rasoul Hosseini
PhD Graduate, 2020
Dissertation: “DESIGN AND OPTIMIZATION OF A MODULAR DC-DC POWER CONVERTER FOR MEDIUM VOLTAGE SHIPBOARD APPLICATIONS.”
Abstract: Power electronic converters rated for medium voltage direct current (MVDC) are promising for electrification of future ships. In shipboard electrification, due to limitation of space, energy and technical maintenance, the high-power density, high efficiency and modularity of the power electronic converters are desired. Utilizing power modules made from wide band gap (WBG) semiconductors like silicon carbide (SiC) and high frequency power transformer (HFPT) can be beneficial for obtaining the high-power density, high efficiency and isolation that is required for the power electronic converters. To provide power for the low voltage (LV) DC loads, a conversion of the power from MVDC main bus to LVDC is needed. Therefore, a DC-DC converter is an essential component of a DC power system. DC-DC converter is a multipurpose element in Unit-based protection architecture (UBPA) which is an architecture that eliminates the need for DC circuit breaker (CB) and instead relies on isolated power electronic converters for protection of the system. Topologies based on Dual active bridge (DAB), Neutral point clamp (NPC) and Modular Multi-level Converter (MMC) are suggested for such a DC-DC converter rated for megawatt (MW) power level. Switching at MV level with high frequency in the ship environment is challenging because of the parasitic coupling that appears between the power module, MV side of the transformer and the ship haul which is made from the materials capable of conducting electricity. Moreover, the transformer used in the isolated DC-DC converter is one of the main contributors to the weight and power density of the converter. In this study, the DAB converter is suggested as a building block for an input series output parallel (ISOP) connected converter and analytical equations are provided for the design. A novel design for the HFPT is proposed and analytical formula is derived for the thermal loss and the leakage inductance of the HFPT. Optimization methodology using evolutionary algorithms method like genetic algorithm is applied to the design to extract the optimal values for a design. A case study is also provided in this study.
University of Illinois, Chicago
Marzieh Karami
PhD Graduate, 2020
Dissertation: “THREE-LEVEL CONVERTERS FOR LOW VOLTAGE ACTIVE FRONT END MOTOR DRIVES.”
Abstract: Electric drives with Active Front End (AFE) converters can provide benefits such as lower harmonic current injections to the grid, smaller size filters, lower THD values and cost saving for injection of power to the grid in brake situations. SiC-MOSFET based two-level converters can be a promising topology for Active Front End (AFE) application in electric drives. The possibility of high switching frequency will make the grid filters smaller. Grid filters are used for EMC and power quality issues. However, there are practical limitations for increasing the switching frequency such as dead time in the gating signals, sampling requirements, and electro-magnetic interference (EMI) considerations, besides the need for high frequency magnetic material for the LCL line filter. However, three-level converters provide the opportunity to switch at a lower frequency and also reduce the filter size compared to a two-level IGBT converter. Three-level converters can be built using low voltage rated modules with lower switching losses and reduced cost compared to SiC based two-level converters. In this work, a comparison between three-level converters and two-level converters is presented focusing on power loss, filter size and application benefits. This comparison is based on an optimization algorithm with the objective function of weight, volume and cost. The topologies and modulation techniques for multilevel converter are categorized at first by a thorough literature survey. The pros and cons for various multilevel topologies and modulation techniques are discussed. The 3-level neutral point clamped (NPC) topology is selected to build a 25 hp, 480V power conversion system. LCL filter design for comparability with grid requirements has been done and the optimal size of the LCL filter is derived considering thermal limitations. To make the comparison between different topologies and switch types possible, it is necessary to consider the maximum junction temperature relation to the switching frequency. In this work, a new modulation method is proposed to improve the performance of three-level converters considering losses and thermal performance. Also, a thermal model is derived for SiC MOSFET power modules that takes the effect of MOSFET channel conduction into consideration. Losses for different modulation methods is analysed and compared for two-level and three-level converters. For a specific application of drives, low speed operation is investigated and the comparison between three-level and two-level converters is considered. The methods for calculating losses are considered carefully to ensure maximizing the utilization of the power semiconductors (for highest power density designs). A novel modulation method is developed for low speed operation of power converters. Finally, an optimization is done for finding minimum volume, highest efficiency, minimum common mode pulses and complying with EMI constraints. This optimization has been broken into multiple steps for reducing the problem size. This will enable us to validate the results more efficiently. Some parts of this optimization are done automatically such as the inductor magnetic and thermal design.
MS Computer Engineering-Power Systems, Sharif University of Technology, 2012
BS Electrical engineering-Power Systems, Sharif University of Technology
Lead Research Engineer
Eaton
Zeljko Jankovic
PhD Graduate, 2020
Research Focus: MODELING AND IMPLEMENTATION OF A MICROGRID-TIE POWER INVERTER
Abstract: The concept of microgrids is a new building block of smart grid that acts as a single controllable entity which allows reliable interconnection of distributed energy resources and loads and provides alternative way of their integration into power system. Due to its specifics, microgrids require different control strategies and dynamics of regulation as compared to ones used in conventional utility grids. All types of power converters used in microgrid share commonalities which potentially affect high frequency modes of microgrid in same manner. There are numerous unique design requirements imposed on microgrid tie inverters, which are dictated by the nature of the microgrid system and bring major challenges that are reviewed and further analyzed in this work. This work introduces, performs a detailed study on, and implements nonconventional control and modulation techniques leading to performance improvement of microgrid tie inverters in respect to aforementioned challenges.
BS from University of Belgrade, Belgrade, Serbia, 2009.
Project Engineer
Rockwell Automation