The global shift towards sustainable energy sources, together with rapid technological advancements, has driven a significant increase in the demand for electric vehicles (EVs) over recent years. This surge in EV adoption highlights the critical need for robust supporting infrastructure, particularly in the deployment of efficient and accessible EV chargers. Gallium Nitride (GaN) is a wide bandgap semiconductor material that offers better performance characteristics compared to traditional silicon-based components in medium-power and high-frequency application. Its higher electron mobility, saturation electron velocity and breakdown electric field make GaN an ideal candidate for high-frequency power conversion applications in EV chargers. To explore the potential of GaN technology in EV charging applications, an 11kW GaN based isolated bidirectional multi-port EV charger with a two-stage architecture has been designed to interconnect bipolar DC grid and electric vehicles. The two stages of the charger consist of a three-level triple active bridge converter and a three-level interleaved buck converter. The TAB converter is an extension of conventional dual active bridge (DAB) converter, offering capability to direct power transmission among three ports. However, the addition of a third port introduces complexity in managing power flow. The TAB converter can operate under various modulation schemes, including three-level and five-level modulation. An analysis of the switching modes associated with each modulation scheme has been
erformed. In order or derive the soft switching range of the converter, the current expression
of series inductors of each port are derived based on generalized-harmonic approximation method and equivalent circuit models. A detailed analysis of the commutation process during critical switching transitions has been conducted, leading to the derivation of the soft
witching criteria for both three-level and five-level operations of the TAB converter. To validate the design and verify the soft switching range, simulations have been carried out. Moreover, the prototype of the 11 kW multi-port EV charger is designed based on calculation and simulation results. The prototype employs a top-side cooled GaN high-electron-mobility transistor (HEMT) to enhance thermal dissipation. Testing of the prototype indicates that the converter can transmit 1.2 kW from the primary to the secondary side at the rated voltage
of 700 V.

This report proposes a design of a 1-megawatt data center that utilizes hydrogen as the primary fuel for power and cooling. Currently, data centers rely on utility grids for their operation. The growing global efforts to achieve sustainability introduce intermittent renewable energy sources, such as solar and wind, into the power grid, which goes against the reliability principles of the data center industry. As computer technologies further permeate our everyday lives, their energy consumption and environmental impact become greater.

The feasibility study aims to investigate the potential of using hydrogen as a primary energy carrier in data center applications in terms of reliability, efficiency, electrical and hydrogen topology, infrastructure layout, and control strategies. A comprehensive review of commercially available and emerging hydrogen technologies related to storage, transport, electricity generation, and cooling was conducted. Based on this literature review, two designs for a hydrogen data center were developed. A modular approach to the design was proposed, where each module is self-contained and responsible for providing the servers with 1 megawatt of electrical power and cooling.

The first low-temperature design utilizes a hydrogen pipeline with pressure swing adsorption purification supplying hydrogen gas to a cogeneration system. This system combines a low-temperature Proton-Exchange Membrane fuel cell and a direct-fired hydrogen single-stage absorption refrigeration cycle into a single unit to deliver stable power and cooling to the servers. The findings indicate that the overall energy efficiency of this design configuration is high, and the technologies are mature enough to be used today. However, the study identified various technological limitations of purification systems that must be addressed with further research and development.
The second high-temperature design eliminates the need for a purification system, relying instead on high-temperature Proton-Exchange Membrane fuel cells coupled to a double-effect absorption refrigeration system. Unfortunately, this design is not feasible in 2024 because the high-temperature fuel cells are in the early stages of development.

A cost analysis was conducted for both designs in the current (2024) and projected (2030) scenarios. The results indicate that at the current level of hydrogen technology development and manufacturing, the operational costs of the low-temperature configuration were comparable to the traditional data centers. However, if hydrogen technology continues to develop according to the projected trends, the proposed designs can achieve up to 50% cost savings compared to the grid-powered data centers. This research showcases the potential for hydrogen as an energy carrier in data center applications, encouraging further research and exploration of hydrogen technologies.

Multilevel inverters are widely used in industries for higher power applications due to low harmonic pollution and high efficiency. On the other hand, the phase-shift switching technique is well-known for its harmonic mitigation performance. However, phase-shift switching has not been regularly implemented on multilevel inverters due to complexity at a higher number of levels and difficulty in voltage balancing of the auxiliary capacitors in the configuration. In this project, the five-level Packed U-Cell inverter (PUC5) will be investigated to design and implement a phase-shift switching technique with an integrated voltage balancing algorithm. The developed technique will be implemented on the real-time simulator and hardware setup.

A literature review will be done on phase-shift switching algorithms and multilevel inverters. Afterward, a phase-shift switching algorithm with an integrated voltage balancing technique will be developed for the PUC5 inverter and simulated in Simulink. Hardware-in-the-loop (HIL) will be done using Opal-RT devices.