Electromechanical transduction is an important component of microelectromechanical systems (MEMS), a technology with wide-ranging applications, including mobile computing, sensors, energy harvesting, and displays. These disparate applications have varying performance requirements, but generally transduction efficiency, mechanical precision, response time, cost, compatibility with photolithography and other fabrication processes, and operability at micro-scale are all desired metrics for MEMS devices. Piezoelectric transduction provides substantial advantages, including precise displacements, quick response times, and high transduction efficiency. These strengths make piezoelectric transduction particularly well-suited for use in resonators, sensors, and energy harvesters. However, piezoelectric transduction also produces much smaller magnitudes of movements than other electromechanical transduction mechanisms, such as thermal or capacitive. This limits the utility of piezoelectricity in designing MEMS actuators. Currently, MEMS designers compensate for this limitation by using sophisticated structures to amplify the small strains produced through the reverse piezoelectric effect. One of the oldest and simplest such designs is the bimorph cantilever beam. Comprised of two distinct, but mechanically connected, piezoelectric layers, the beam uses piezoelectricity to cause longitudinal strain in both layers. As one layer expands, the other contracts—this opposing motion creates a bending moment, causing the beam to deflect out-of-plane, often at substantially higher displacements than the expansion or contraction of either piezoelectric layer. This thesis presents a design and simulation results for a unimorph beam comprised of only one piezoelectric layer. Through use of a novel electrode pattern that applies a non-uniform electric field, this beam acts as a quasi-bimorph, creating a bending moment without the need for two distinct piezoelectric layers.

In this thesis, a maximum power point tracking (MPPT) for multiple input single output (MISO) converter is presented such that power generated from multiple individual energy sources can be combined to deliver the maximum amount of power to a common resistive load. Typically, MISO converters will employ techniques that yield equal current sharing from each energy source. However, this may not be desirable since each source may be rated at different power ratings and/or may experience different operating conditions, preventing the system MISO converter to acquire the most available total power from the sources. Utilizing MPPT control would therefore be beneficial in maximizing the output power of the MISO converter system. In this thesis, a proposed two-stage converter system is presented to incorporate the MPPT control in the MISO system. The initial stage implements the MPPT, drawing as much power from the corresponding source. The second stage regulates the output voltage of the MPPT. To evaluate the performance and efficiency of the proposed system, simulation with two solar panels as the sources was performed using Simulink with various test cases to fully explore the viability of the system. Simulation results were also used to compare with those obtained from a system without the MPPT. Results show that the proposed system with the MPPT stage is able to improve input regulation and increase the total amount of power acquired from the sources compared to the system without the MPPT. Further testing with hardware setup confirms the simulation results and demonstrates that even with large differences in input powers, the most total amount of power is achieved and utilized.

The focus of this thesis is to research, analyze, and design a reliable and economical control system for the Cal Poly Wind Energy Capture System (WECS). A dynamic permanent magnet generator model is adopted from [1] and [2] and combined with an existing wind turbine model to create a non-linear time varying model in MATLAB. The model is then used to analyze potentially harmful electrical disturbances, and to define safe operating limits for the WECS. An optimal operating point controller utilizing a PID speed loop is designed with combined optimization criteria and the final controller design is justified by comparing performance measures of energy efficiency and mitigation of mechanical loads. The report also discusses implications for a WECS when blade characteristics are mismatched with the generator. Finally, possible ways to improve the performance of the Cal Poly WECS are addressed.

Solar-based converter design is of paramount importance in 2023 due to the rapidly increasing demand for renewable energy sources and the need to reduce carbon emissions to mitigate the effects of climate change. As the world continues to shift towards a sustainable future, solar power is expected to play a critical role in meeting the growing energy demand. A multiport converter with renewable energy sources and storage unit must be able to regulate the power output from the panels and ensure that it is compatible with the grid or other energy storage systems. In this dissertation, different multiport systems have been designed and analyzed along with advanced control methods for solar battery integration. An LLC converter-based design has been developed to efficiently convert and regulate energy from solar panels and battery storage. This converter is designed to have multiple ports to enable the simultaneous charging and discharging of multiple batteries, making it suitable for both residential and commercial applications. A multiport single LLC tank-based converter is an efficient and versatile solution for energy storage and management in solar systems. Its multiple ports and resonant LLC topology make it suitable for a range of applications, from small-scale residential systems to larger commercial systems. Additionally, other MPC grid-integrated topologies are also investigated in this dissertation. All these circuits aim to track maximum power from the energy sources and require reliable control strategies. In this regard, multiple advanced hybrid control methods based on fuzzy logic and neural network have been developed as a part of this dissertation. All the simulation studies have been performed matlab/Simulink as well as plecs platform and the experimental prototypes have been tested to verify the concepts.

The growing concerns about climate change that has already affected the environment negatively in many ways call for immediate actions to keep global warming below the limit set out in the Paris agreement of 1.5 degrees Celsius above the pre-industrial level. The energy and transportation sectors are considered the main sources of greenhouse gas emissions that cause global warming. Therefore, the electrification of these sectors and making them environmentally friendly should be prioritized. Internal combustion engine vehicles account for the majority of CO2 emissions; hence, replacing them with Electric Vehicles (EV) has the highest potential to slow down global warming. However, they must be charged from renewable sources such as Photovoltaic (PV) to eliminate the indirect CO2 emissions, so EVs become environmentally friendly in the true sense. To increase the rate of PVs and EVs penetration into the grid, energy storage (ES) should be added to the PV system to overcome its intermittency nature and to the EV charging stations to reduce their negative impacts on the electric grid. In this dissertation, novel multiport multilevel converters that facilitate the integration of ES with the PV systems and EV charging stations and fit various applications seamlessly and efficiently are designed, developed, and verified using the state-of-the-art low voltage Gallium Nitride (GaN) power semiconductor devices. These developed multiport multilevel converters have achieved very high efficiency, high power density, low harmonic distortion, light weight, and compact size. They facilitate interfacing multiple sources and loads in a single unit. They ease adding ES to the PV system. Moreover, they facilitate interfacing the Grid, the PV, the EV, and the ES locally at the charging stations. In addition, these multiport multilevel converters can be employed in several other applications, such as ES + PV systems for standalone AC load and uninterrupted power supply designs.

Many settlements in Sub Saharan Africa (SSA) lack access to electricity which is a necessary resource for development. Given the geography and population patterns in the region, extending national grids is economically unviable for many of the un-electrified settlements. Meanwhile the region is endowed with renewable resources which can be exploited in off-grid mode for electricity generation. This thesis examines the importance of off-grid technologies for onward electrification in the SSA region. The exercise inspires an electricity planning problem that can be analytically specified but is computationally intensive and impractical for real sized problems. Heuristic methods must therefore be used. We develop two new heuristic solution methods which draw on standard algorithms i.e. lexicographic algorithm and genetic algorithm to solve the problem. The new solution methods together with two existing heuristic algorithms in the literature are applied to a case study of Ghana. We find that the electrification schemes yielded by all four solution methods/algorithms suggest off-grid technologies, especially solar, are important for onward electrification in SSA. Locations that were assigned off-grid technologies in the algorithms mentioned above are typically rural where livelihoods are based on small scale farming. Currently, adoption of renewable resource technologies is low in these locations. We therefore develop a dynamic stochastic farm household model to examine the extent to which market failures impact self-funded investment in solar panels by farmers in rural SSA. We find that credit restrictions and risk affect solar panel investment to varying degrees. Using simulations of the policy functions, we find that the expected investment cycle for a credit constrained household in a stochastic farm income environment is 30 years if investment in solar panels is irreversible. In a reversible investment scenario, the expected investment cycle is 5 years only. Reversibility is therefore a major determinant of solar panel adoption among poor farmers.

Industries across world use different methods to secure the quality of the contract deliverables. These deliverables are carefully defined in an agreement between project owner and agent (buyer and seller) however, there are several reasons that the quality of the outcome does not fulfill the desired pre-agreed quality. In aerospace as well as power & energy industries, the delivered products (outcome of the contracts) should endure a long lifespan. Although guarantee and warrantees are being used in contracts to secure the quality of the outcome for a short period of time after delivery, in several cases, the quality of the delivered product fails right after guarantee expiration date. Therefore, guarantee and warrantee are not considered to be a preventive means while the requirement for such preventive tool is undeniable. This case study gathers data from aerospace as well as power and energy industries on how these two industries shape up their agreements and what sort of incentives they use and if these applied incentives have assisted them to reach the target. These data will be analyzed in comparison to similar conducted research in this field.

Fossil fuel will eventually become exhausted. Also, fossil fuels produce large amounts of carbon dioxide, which cannot only bring environment pollution, but can also cause global warming. Therefore, clean and renewable energy sources should be investigated. In this project, renewable wind power was considered. Wind energy is free, clean and available in large quantities, although it is difficult to use due to its stochastic variability. Energy storage can reduce this variability allowing energy production to match energy demand. In this study, different kinds of energy storage approaches were introduced, compared, and simulated by using half hourly wind data from the Met Office, UK, and half hourly load data from the University of Bath, UK. Hydrogen has higher mass energy density than all other energy storage methods. It is seen as a versatile energy carrier of the future, complementary to electricity and with the potential to replace fossil fuels due to its zero carbon emissions and abundance in nature. On the other hand, because hydrogen is the lightest element under normal conditions; the same amount of hydrogen must occupy a huge volume compared to other elements. The mature technology for converting hydrogen into electricity has high cost and low efficiency. These are big issues that limit the usage of hydrogen energy storage methods. Using wind and load data, a new algorithm was developed and used for sizing the wind turbine, and energy storage requirements. The traditional way to supply energy is distributing electricity, but in this PhD research, there are some discussions about a new method, hydrogen transport-hydrogen pipeline. From the results of the comparison and algorithm, a practical hydrogen energy storage system for the University of Bath network was proposed and designed. In the proposed design the energy from a wind turbine was directed to the load and the remaining excess power was used to produce hydrogen by water electrolysis. The hydrogen was stored in a high pressure compressed tank, and finally a hydrogen fuelled combined cycle gas turbine was used to convert the hydrogen to electricity. In this thesis, the dynamics of the complete hydrogen cycle energy storage and recovery mechanism are discussed, identifying potential applications such as power smoothing, peak lopping and extending power system controller ranges. The results of calculations of the payback time and revenue verify the feasibility of the designed hydrogen energy storage system. The main objective of the PhD was to design a practical hydrogen energy storage system for micro-grid applications. During this research, hydrogen energy storage was investigated to show that it does solve the problems arising from renewable energy.

As California continues to integrate more renewable energy into its electrical system, the state has experienced a corresponding rise in photovoltaic system installations. PV arrays are a unique source of power generation in that they are affected by the location of the sun, shading, and temperature changes. These characteristics make solar one of the most highly variable forms of renewable energy. In order to improve solar power’s consistency, PV systems require a supplemental source of power. The primary focus of this paper is to determine if distributed energy storage systems can be used to reduce the effect of solar intermittency. This paper examines the test data and system specifications of an experimental DESS. The benefits of using a DESS in a PV system are further studied using computer simulation modeling. This paper also shows through computer simulations how a maximum power point tracker can increase a PV array’s power output. The results of this thesis demonstrate that DESS’s are capable of smoothing out highly variable load profiles caused by intermittent solar power.

Thesis (M.S. in electrical engineering)--Washington State University, December 2007. / Includes bibliographical references (p. 57-58).