With the demand increase for electricity, the ever-increasing awareness of environmental issues, coupled with rolling blackouts, the role of renewable energy generation is increasing along with the thirst for electricity and awareness of environmental issues. This dissertation proposes the design and implementation of PV-firming and optimization algorithms for three-port microinverters. Novel strategies are proposed in Chapters 3 and 4 for harvesting stable solar power in spite of intermittent solar irradiance. PV firming is implemented using a panel-level three-port grid-tied PV microinverter system instead of the traditional high-power energy storage and management system at the utility scale. The microinverter system consists of a flyback converter and an H-bridge inverter/rectifier, with a battery connected to the DC-link. The key to these strategies lies in using static and dynamic algorithms to generate a smooth PV reference power. The outcomes are applied to various control methods to charge/discharge the battery so that a stable power generation profile is obtained. In addition, frequency-based optimization for the inverter stage is presented. One of the design parameters of grid-tied single-phase H-bridge sinusoidal pulse-width modulation (SPWM) microinverters is switching frequency. The selection of the switching frequency is a tradeoff between improving the power quality by reducing the total harmonic distortion (THD), and improving the efficiency by reducing the switching loss. In Chapter 5, two algorithms are proposed for optimizing both the power quality and the efficiency of the microinverter. They do this by using a frequency tracking technique that requires no hardware modification. The first algorithm tracks the optimal switching frequency for maximum efficiency at a given THD value. The second maximizes the power quality of the H-bridge micro-inverter by tracking the switching frequency that corresponds to the minimum THD. Real-time PV intermittency and usable capacity data were evaluated and then further analyzed in MATLAB/SIMULINK to validate the PV firming control. The proposed PV firming and optimization algorithms were experimentally verified, and the results evaluated. Finally, Chapter 6 provides a summary of key conclusions and future work to optimize the presented topology and algorithms.

The extensive use of Integrated Circuits (ICs) means complex working conditions for these tiny chips. To guarantee the ICs could work properly in various environments, some special protection strategies are required to improve the reliability of system. From all the possible reliability issues, the electrostatics discharge (ESD) might be the most common one. The peak current of electrostatics can be as high as tens of amperes and the peak voltage can be over thousand voltages. In contrast, the size of semiconductor device fabricated is continuing to scale down, making it even more vulnerable to high level overstress and current surge induced by ESD event. To protect the on-chip semiconductor from damage, some extra "clamp cells" are put together to consist a network. The network can redirect the superfluous current through the ESD network and clamp the voltage to a low level. In this dissertation, one design concept is introduced that uses the combination of some basic ESD devices to meet different requirements first, and then tries to establish parasitic current path among these devices to further increase the current handling capability. Some design cases are addressed to demonstrate this design concept is valid and efficient: 1. A combination of silicon-controlled-rectifier (SCR) and diode cluster is implemented to resolve the overshoot issue under fast ESD event. 2. A new SCR structure is introduced, which can be used as "padding" device to increase the clamping voltage without affecting other parameters. Based on this "padding" device, two design cases are introduced. 3. A controllable SCR clamp structure is presented, which has high current handling capability and can be controlled with by small signal. All these structures and topologies described in this dissertation are compatible with most of popular semiconductor fabrication process.

The energy market is on the verge of a paradigm shift as the emergence of renewable energy sources over traditional fossil fuel based energy supply has started to become cost competitive and viable. Unfortunately, most of the attractive renewable sources come with inherent challenges such as: intermittency and unreliability. This is problematic for today's stable, day ahead market based power system. Fortunately, it is well established that energy storage devices can compensate for renewable sources shortcomings. This makes the integration of energy storage with the renewable energy sources, one of the biggest challenges of modern distributed generation solution. This work discusses, the current state of the art of power conversion systems that integrate photovoltaic and battery energy storage systems. It is established that the control of bidirectional power flow to the energy storage device can be improved by optimizing its modulation and control. Traditional multistage conversion systems offers the required power delivery options, but suffers from a rigid power management system, reduced efficiency and increased cost. To solve this problem, a novel three port converter was developed which allows bidirectional power flow between the battery and the load, and unidirectional power flow from the photovoltaic port. The individual two-port portions of the three port converter were optimized in terms of modulation scheme. This leads to optimization of the proposed converter, for all possible power flow modes. In the second stage of the project, the three port converter was improved both in terms of cost and efficiency by proposing an improved topology. The improved three port converter has reduced functionality but is a perfect fit for the targeted microinverter application. The overall control system was designed to achieve improved reference tracking for power management and output AC voltage control. The bidirectional converter and both the proposed three port converters were analyzed theoretically. Finally, experimental prototypes were built to verify their performance.

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.