Matching Items (66)
Filtering by
- All Subjects: Electrical Engineering
- Creators: Holbert, Keith E.
Description
An optimal energy scheduling procedure is essential in an isolated environment such as naval submarines. Conventional naval submarines include diesel-electric propulsion systems, which utilize diesel generators along with batteries and fuel cells. Submarines can charge the batteries by running diesel-electric generators only at the surface or at snorkeling depth. This is the most dangerous time for submarines to be detectable by acoustic and non-acoustic sensors of enemy assets. Optimizing the energy resources while reducing the need for snorkeling is the main factor to enhance underwater endurance. This thesis introduces an energy management system (EMS) as a supervisory tool for the officers onboard to plan energy schedules in order to complete various missions. The EMS for a 4,000-ton class conventional submarine is developed to minimize snorkeling and satisfy various conditions of practically designed missions by optimizing the energy resources, such as Lithium-ion batteries, Proton-exchange membrane fuel cells, and diesel-electric generators. Eventually, the optimized energy schedules with the minimum snorkeling hours are produced for five mission scenarios. More importantly, this EMS performs deterministic and stochastic operational scheduling processes to provide secured optimal schedules which contains outages in the power generation and storage systems.
ContributorsJeon, Byeongdoo (Author) / Hedman, Mojdeh Khorsand (Thesis advisor) / Holbert, Keith E. (Committee member) / Wu, Meng (Committee member) / Arizona State University (Publisher)
Created2020
Description
Climate change is affecting power generation globally. Increase in the ambient air
temperature due to the emission of greenhouse gases, caused mainly by burning of fossil fuels, is the most prominent reason for this effect. This increase in the temperature along with the changing precipitation levels has led to the melting of the snow packs and increase in the evaporation levels, thus affecting hydropower. The hydropower in the United States might increase by 8%-60% due to Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 scenarios respectively by 2050. Wind power generation is mainly affected by the change in the wind speed and solar power generation is mainly affected by the increase in the ambient air temperature, changes in precipitation and solar radiation. Solar power output reduces by approximately a total of 2.5 billion kilowatt- hour (kWh) by 2050 for an increase in ambient air temperature of 1 degree Celsius. Increase in the ambient air and water temperature mainly affect the thermal power generation. An increase in the temperature as per the RCP 4.5 and RCP 8.5 climate change scenarios could decrease the total thermal power generation in the United States by an average of 26 billion kWh and a possible income loss of around 1.5 billion dollars. This thesis discusses the various effects of climate change on each of these four power plant types.
temperature due to the emission of greenhouse gases, caused mainly by burning of fossil fuels, is the most prominent reason for this effect. This increase in the temperature along with the changing precipitation levels has led to the melting of the snow packs and increase in the evaporation levels, thus affecting hydropower. The hydropower in the United States might increase by 8%-60% due to Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 scenarios respectively by 2050. Wind power generation is mainly affected by the change in the wind speed and solar power generation is mainly affected by the increase in the ambient air temperature, changes in precipitation and solar radiation. Solar power output reduces by approximately a total of 2.5 billion kilowatt- hour (kWh) by 2050 for an increase in ambient air temperature of 1 degree Celsius. Increase in the ambient air and water temperature mainly affect the thermal power generation. An increase in the temperature as per the RCP 4.5 and RCP 8.5 climate change scenarios could decrease the total thermal power generation in the United States by an average of 26 billion kWh and a possible income loss of around 1.5 billion dollars. This thesis discusses the various effects of climate change on each of these four power plant types.
ContributorsPenmetsa, Vikramaditya (Author) / Holbert, Keith E. (Thesis advisor) / Hedman, Mojdeh (Committee member) / Wu, Meng (Committee member) / Arizona State University (Publisher)
Created2020
Description
Transmission line capacity is an obstacle for the utilities because there is a load increment annually, and new power plants are being connected, which requires an update. Energy router (ER) is a device that provides an additional degree of freedom to the utilities by controlling the reactive power. The ER reactive power injection is demonstrated by changing the line's reactance value to increase its capacity and give the utility a deferral time for the project upgrade date. Changing the reactance manually and attaching Smart Wire's device to the branches have effectively solved the overload in three locations of a local utility in Arizona (LUA) system.
Furthermore, electric vehicle charging stations (EVCSs) have been increasing to meet EV needs, which calls for an optimal planning model to maximize the profits. The model must consider both the transportation and power systems to avoid damages and costly operation. Instead of coupling the transportation and power systems, EVCS records have been analyzed to fill the gap of EV demand. For example, by accessing charging station records, the moment knowledge of EV demand, especially in the lower order, can be found. Theoretically, the obtained low-order moment knowledge of EV demand is equivalent to a second-order cone constraint, which is proved. Based on such characteristics, a chance-constrained (CC) stochastic integer program for the planning problem is formulated. For planning EV charging stations with ER, this method develops a simple ER model to investigate the interaction between the mobile placement of power flow controller and the daily pattern of EV power demand.
Furthermore, electric vehicle charging stations (EVCSs) have been increasing to meet EV needs, which calls for an optimal planning model to maximize the profits. The model must consider both the transportation and power systems to avoid damages and costly operation. Instead of coupling the transportation and power systems, EVCS records have been analyzed to fill the gap of EV demand. For example, by accessing charging station records, the moment knowledge of EV demand, especially in the lower order, can be found. Theoretically, the obtained low-order moment knowledge of EV demand is equivalent to a second-order cone constraint, which is proved. Based on such characteristics, a chance-constrained (CC) stochastic integer program for the planning problem is formulated. For planning EV charging stations with ER, this method develops a simple ER model to investigate the interaction between the mobile placement of power flow controller and the daily pattern of EV power demand.
ContributorsAlali, Yousef (Author) / Weng, Yang (Thesis advisor) / Cui, Qiushi (Committee member) / Holbert, Keith E. (Committee member) / Arizona State University (Publisher)
Created2020
Description
In recent years, the Silicon Super-Junction (SJ) power metal-oxide semiconductor field-effect transistor (MOSFET), has garnered significant interest from spacecraft designers. This is due to their high breakdown voltage and low specific on-state resistance characteristics. Most of the previous research work on power MOSFETS for space applications concentrated on improving the radiation tolerance of low to medium voltage (~ 300V) power MOSFETs. Therefore, understanding and improving the reliability of high voltage SJMOS for the harsh space radiation environment is an important endeavor.In this work, a 600V commercially available silicon planar gate SJMOS is used to study the SJ technology’s tolerance against total ionizing dose (TID) and destructive single event effects (SEE), such as, single event burnout (SEB) and single event gate rupture (SEGR). A technology computer aided design (TCAD) software tool is used to design the SJMOS and simulate its electrical characteristics.
Electrical characterization of SJMOS devices showed substantial decrease in threshold voltage and increase in leakage current due to TID. Therefore, as a solution to improve the TID tolerance, metal-nitride-oxide-semiconductor (MNOS) capacitors with different oxide
itride thickness combinations were fabricated and irradiated using a Co-60 gamma-source. Electrical characterization showed all samples with oxide
itride stack gate insulators exhibited significantly higher tolerance to irradiation when compared to metal-oxide-semiconductor capacitors.
Heavy ion testing of the SJMOS showed the device failed due to SEB and SEGR at 10% of maximum rated bias values. In this work, a 600V SJMOS structure is designed that is tolerant to both SEB and SEGR. In a SJMOS with planar gate, reducing the neck width improves the tolerance to SEGR but significantly changes the device electrical characteristics. The trench gate SJ device design is shown to overcome this problem. A buffer layer and larger P+-plug are added to the trench gate SJ power transistor to improve SEB tolerance. Using TCAD simulations, the proposed trench gate structure and the tested planar gate SJMOS are compared. The simulation results showed that the SEB and SEGR hardness in the proposed structure has improved by a factor of 10 and passes at the device’s maximum rated bias value with improved electrical performance.
Electrical characterization of SJMOS devices showed substantial decrease in threshold voltage and increase in leakage current due to TID. Therefore, as a solution to improve the TID tolerance, metal-nitride-oxide-semiconductor (MNOS) capacitors with different oxide
itride thickness combinations were fabricated and irradiated using a Co-60 gamma-source. Electrical characterization showed all samples with oxide
itride stack gate insulators exhibited significantly higher tolerance to irradiation when compared to metal-oxide-semiconductor capacitors.
Heavy ion testing of the SJMOS showed the device failed due to SEB and SEGR at 10% of maximum rated bias values. In this work, a 600V SJMOS structure is designed that is tolerant to both SEB and SEGR. In a SJMOS with planar gate, reducing the neck width improves the tolerance to SEGR but significantly changes the device electrical characteristics. The trench gate SJ device design is shown to overcome this problem. A buffer layer and larger P+-plug are added to the trench gate SJ power transistor to improve SEB tolerance. Using TCAD simulations, the proposed trench gate structure and the tested planar gate SJMOS are compared. The simulation results showed that the SEB and SEGR hardness in the proposed structure has improved by a factor of 10 and passes at the device’s maximum rated bias value with improved electrical performance.
ContributorsMuthuseenu, Kiraneswar (Author) / Barnaby, Hugh (Thesis advisor) / Kozicki, Michael (Committee member) / Holbert, Keith E. (Committee member) / Gonzalez Velo, Yago (Committee member) / Arizona State University (Publisher)
Created2020
Description
This work investigates the effects of ionizing radiation and displacement damage on the retention of state, DC programming, and neuromorphic pulsed programming of Ag-Ge30Se70 conductive bridging random access memory (CBRAM) devices. The results show that CBRAM devices are susceptible to both environments. An observable degradation in electrical response due to total ionizing dose (TID) is shown during neuromorphic pulsed programming at TID below 1 Mrad using Cobalt-60. DC cycling in a 14 MeV neutron environment showed a collapse of the high resistance state (HRS) and low resistance state (LRS) programming window after a fluence of 4.9x10^{12} n/cm^2, demonstrating the CBRAM can fail in a displacement damage environment. Heavy ion exposure during retention testing and DC cycling, showed that failures to programming occurred at approximately the same threshold, indicating that the failure mechanism for the two types of tests may be the same. The dose received due to ionizing electronic interactions and non-ionizing kinetic interactions, was calculated for each ion species at the fluence of failure. TID values appear to be the most correlated, indicating that TID effects may be the dominate failure mechanism in a combined environment, though it is currently unclear as to how the displacement damage also contributes to the response. An analysis of material effects due to TID has indicated that radiation damage can limit the migration of Ag+ ions. The reduction in ion current density can explain several of the effects observed in CBRAM while in the LRS.
ContributorsTaggart, Jennifer L (Author) / Barnaby, Hugh J (Thesis advisor) / Kozicki, Michael N (Committee member) / Holbert, Keith E. (Committee member) / Yu, Shimeng (Committee member) / Arizona State University (Publisher)
Created2018
Description
Digital systems are essential to the technological advancements in space exploration. Microprocessor and flash memory are the essential parts of such a digital system. Space exploration requires a special class of radiation hardened microprocessors and flash memories, which are not functionally disrupted in the presence of radiation. The reference design ‘HERMES’ is a radiation-hardened microprocessor with performance comparable to commercially available designs. The reference design ‘eFlash’ is a prototype of soft-error hardened flash memory for configuring Xilinx FPGAs. These designs are manufactured using a foundry bulk CMOS 90-nm low standby power (LP) process. This thesis presents the post-silicon validation results of these designs.
ContributorsGogulamudi, Anudeep Reddy (Author) / Clark, Lawrence T (Thesis advisor) / Holbert, Keith E. (Committee member) / Brunhaver, John (Committee member) / Arizona State University (Publisher)
Created2016