The rising demand for energy and the depletion of fossil fuels has led to the rapid adoption of renewable energy sources. However, their variability poses challenges. Battery-based storage systems offer a solution, storing excess energy for peak demand or low generation periods. High-gain converters are key in efficiently integrating these systems with the grid by boosting battery voltage. Adding cell-integrated power electronics enhances reliability by providing localized control, reducing the impact of individual cell failures. The study investigates the efficiency of cell-level high-gain DC-DC two-stage converters for integrating renewable energy into the grid. To optimize performance across diverse DC link voltages, a comparison of different first-stage converters is performed based on factors such as component selection and switch losses. Following careful calculations and selection, the chosen converter is paired with an inverter for seamless grid integration. Operating at a power level of 200W, the converters transform low battery cell voltage from 2.5V to 40V into a grid-compatible 360V output. Results demonstrate the selected converter's superior efficiency and voltage regulation, displaying its suitability for grid integration applications. This research underscores the importance of such converters in facilitating reliable renewable energy integration, offering a pathway toward sustainable energy utilization. In the subsequent phase, the investigation delves deeper into assessing the performance of the LLC converter, particularly focusing on how it reacts to the secondary effects of the converter. This investigation gives special attention to a significant factor known as Intra-Winding capacitance, which refers to the unintended capacitance existing within the windings of the converter's transformer in close proximity. Furthermore, this analysis employs the General Harmonic Approximation (GHA) and compared against traditional Fundamental Harmonic Approximation (FHA).

Switch-mode power converters operate at frequencies ranging from tens to hundreds of kilohertz and tend to generate significant conducted EMI within the regulated frequency band of 0.15-30 MHz. Converters typically require an input filter to comply with electromagnetic compatibility standards to prevent high-frequency currents from traveling through the power source conductors. The traditional EMI filters are usually made of passive components, which are substantial in size, sometimes occupying as much as one-third to one-fourth of the total volume, limiting the power density of the power converters. An alternative to bulky passive EMI filters is the utilization of active electronics, which inject voltages or currents to counteract the interference signal. This work introduces a boost converter in conjunction with a synchronized switch mode Active Electromagnetic Interference Filter (AEF), which reduces energy storage requirements compared to passive EMI filters. The proposed AEF operating at a frequency of 30 MHz effectively mitigates additional EMI into the system as its operational frequency lies beyond the typical range of conducted EMI. The AEF is realized using a synchronous buck converter with a series resonant tank and the current configuration is designed to counteract the ripple component of the boost converter. Firstly, this work presents the comprehensive analytical modeling of the AEF circuit consisting of a series resonant tank to determine the variation of AEF current magnitude to circuit parameters, and duty-controlled switching in the proposed AEF is implemented using high-speed analog circuits to generate pulse width modulated (PWM) signals for the filter. The proposed methodology controls the magnitude of AEF current to a desired value in an open loop to reduce the complexity of the circuit. Further, the AEF is employed in a (6-12)V-to-24V boost converter switching at 150 kHz and has been found to attenuate the fundamental ripple component. From the experimental results, an attenuation of 23dB is achieved using the proposed AEF and a reduction of LC product by a factor of 16 in the AEF and the effective volume of the AEF by 47% compared to that of a single-stage fully passive LC filter.

The burgeoning adoption of electric vehicles (EVs) necessitates a comprehensive exploration of the charging infrastructure, delving into both the optimization of EV charger converters and the pivotal role of EV chargers in the power grid. This dissertation comprises six technical chapters, with a focused exploration of converters in Chapters 2 to 4 and an in-depth analysis of the role of EVs in power grids in Chapters 5 to 7.Chapters 2 to 4 showcase advancements in EV charger converters. Chapter 2 introduces a novel active harmonic reduction technique, mitigating the dominant third-order harmonic in the power factor corrector circuit’s input current. This innovation not only enhances grid power quality but also marks a critical step toward efficient and sustainable EV charging. In Chapter 3, a new gate signal modulation method in the dc-dc dual active converter minimizes conduction and switching losses, optimizing the charging process. Chapter 4 extends the converter optimization paradigm with a DC link voltage optimization method, enhancing the efficiency of the entire EV charger across ac-dc and dc-dc stages over the battery charging cycle. Chapters 5 to 7 transition seamlessly to the role of EV charging systems in the power grid. Chapter 5 explores the optimal utilization of bidirectional EVs for grid frequency support during critical events such as loss of generation and frequency drops. This chapter highlights the potential for EVs not merely as energy consumers but as dynamic contributors to grid stability. Chapter 6 presents a dynamic EV charging pricing strategy to distribute the EVs between charging stations (CSs) uniformly and thereby increase the revenue of the charging station operator (CSO) and enhance the charging satisfaction of EV users. Finally, in Chapter 7, a two-stage stochastic programming approach is developed for electric energy procurement in EV charging stations equipped with battery energy storage and photovoltaic generation. This innovative approach provides a roadmap for sustainable energy procurement, emphasizing the synergy between EV charging stations and renewable energy sources. In conclusion, this dissertation provides a holistic and pioneering exploration of EV charging systems, from converter optimization to grid integration. The research contributes significantly to the advancement of EV charging technology, offering solutions to enhance efficiency, power quality, and grid stability. The findings not only address current challenges in electric mobility but also lay a foundation for a sustainable and resilient energy future.

Power amplifiers and tuneable matching networks for plasma generation systems arebeing continuously advanced, and recent innovations have shown tremendous improvements in their size, efficiency, and capability. These improvements must ultimately be validated on a live plasma chamber, but this is costly and time-consuming, and debugging errors or failures is a challenge owing to the highly dynamic nature of the plasma and the experimental prototype nature of the advancements. This work addresses this challenge by developing a reactive load emulation system that can mimic the inductive reactance of a live plasma chamber. This includes a study of the saturation characteristics of low-permeability, high-frequency materials, demonstration of the suitability of this method for plasma emulation, and the design of an inductor array platform which verifies the approach.

With the emergence of electric transportation and the infrastructure for electric vehicles (EVs), numerous viable approaches and topologies have emerged. In order to improve the power quality of the grid, it is essential for Onboard Battery Chargers (OBC) for electric vehicles to maintain a power factor closer to unity. This study mainly focuses on two prominent PFC topologies, Totem-pole PFC (TPFC) and H-Bridge PFC (HPFC), which are simple to implement and capable enough of providing high operating efficiency. This study elucidates the comprehensive comparison of the TPFC and HPFC converters using the comprehensive mathematical modeling approach, simulation models, and the hardware experiments. Also, the comparison of the EMI filter requirement and design of DM EMI filter for both the topologies is also extensively illustrated in this study. Firstly, focusing the comprehensive mathematical models of TPFC and HPFC converters, which includes the mathematical formation of the duty cycle for both the converters incorporating the discretized input current controller into the mathematical model which gives more closer comparison when it is compared to simulation models and the hardware experiment model operations. The input current FFT analysis and the THD modeling are also covered in the mathematical modeling of TPFC and HPFC converters. Moreover, the EMI noise is modeled, and the corresponding EMI filter is also designed for both the PFC topologies. Further, the simulation models of TPFC and HPFC converters are also developed and the outputs of the simulation models show an input AC current is precisely following the input AC voltage and also the output voltage of constant 400V is attained for both the PFC converters. Similarly, for the experimental results, the constant 400V regulated DC output voltage is obtained and the input AC current is following the input AC voltage with the power factor of 0.983 for TPFC and 0.99 for HPFC converter. Moreover, the implementation of the EMI filter at the front end of the converter succinctly attenuates the EMI noise and complied within the FCC Class A limit for both TPFC and HPFC converters.

Adhering to an ever-increasing demand for innovation in the field of onboard electric vehicle (EV) charging, several technical aspects pertaining to the design and performance enhancement of integrated multi-port charger topologies are discussed in this study. This study also elucidates various research challenges pertaining to each module of the topology and elucidates technically validated solutions for each.Firstly, targeting the input side totempole power factor corrector (TPFC) circuit, a novel digital filter based Active Mitigation Scheme (AMS) is proposed to curb the third harmonic component, along with a novel discretized sampling-based robust control scheme. Experimental verification of these techniques yields an enhanced Total Harmonic Distortion (THD) of 1.68%, enhanced efficiency of 98.1% and resultant power factor of 0.998 (lag). Further, focusing on the bidirectional CLLC based DC/DC converter topology, a general harmonic approximation (GHA) based secondary side turnoff current minimization technique is discussed. Numerous fabrication and design-based constraints and correlations for parametric modelling of high frequency planar transformer (HFPT) are explained with analytical and 3D Finite Element Analysis (FEA) findings. Further, characterization of the plant transfer function of all-inclusive CLLC model is described along with hybrid Sliding Mode Control (SMC) based control scheme. The steady state experimental results at 1kW rated load show a peak efficiency of 98.49%, while the quantification of dynamic response portray a settling time reduction of 46.4% and an over/undershoot reduction of 33%. Further, comprehensive modeling of triple active bridge (TAB) DC/DC converter topology is presented with special focus on the control scheme and decoupling capabilities to independently regulate the output bridges. With an objective to reduce the overall losses and to add a dimension of controllability, a three-loop control scheme is proposed with power flow optimization. Inculcating the benefits of multiport and resonant topologies, a comprehensive multi-variable loss optimization study of a Triple Active C^3 L^3 (TAC^3L^3) converter is discussed. The performance of eight different hybrid modulation schemes is compared with respect to the developed global loss minimization objective function. Experimental validations for various loading conditions are presented for a wide-gain bidirectional operation (400V/500-600V/24-28V), portraying a peak converter efficiency of 97.42%.

Wide-BandGap (WBG) material-based switching devices such as gallium nitride (GaN) High Electron Mobility Transistors (HEMTs) and Silicon Carbide (SiC) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) are considered very promising and valuable candidates for replacing conventional Silicon (Si) MOSFETs in various industrial high-frequency high-power applications, mainly because of their capabilities of higher switching frequencies with less switching and conduction losses. However, to make the most of their advantages, it is crucial to understand the intrinsic differences between WBG-based and Si-based switching devices and investigate effective means to safely, efficiently, and reliably utilize the WBG devices. Firstly, a comprehensive understanding of traditional Modular Multilevel Converter (MMC) topology is presented. Different novel SubModule (SM) topologies are described in detail. The low frequency SM voltage fluctuation problem is also discussed. Based on the analysis, some novel topologies which manage to damp or eliminate the voltage ripple are illustrated in detail. As demonstrated, simulation results of these proposed topologies verify the theory. Moreover, the hardware design considerations of traditional MMC platform are discussed. Based on these, a 6 kW smart Modular Isolated Multilevel Converter (MIMC) with symmetrical resonant converter based Ripple current elimination channels is delivered and related experimental results further verify the effectiveness of proposed topology. Secondly, the evolution of GaN transistor structure, from classical normally-on device to normally-off GaN, is well-described. As the benefits, channel current capability and drain-source voltage are significantly boosted. However, accompanying the evolution of GaN devices, the dynamic on-resistance issue is one of the urgent problems to be solved since it strongly affects the GaN device current and voltage limit. Unlike traditional methods from the perspective of transistor structure, this report proposes a novel Multi-Level-Voltage-Output gate drive circuit (MVO-GD) aimed at alleviating the dynamic on-resistance issue from engineering point of view. The comparative tests of proposed MVO-GD and the standard 2-level gate driver (STD-GD) are conducted under variable test conditions which may affect dynamic on-resistance, such as drain-source voltage, gate current width, device package temperature and so on. The experimental waveforms and data have been demonstrated and analyzed.