This dissertation explores the feasibility of utilizing Silicon Carbide (SiC)Electroluminescence (EL) to estimate current from a SiC MOSFET’s body diode in classical power converter feedback control systems. The study delves into the current and temperature dependencies of SiC EL, demonstrating how light intensity at key wavelengths (390 nm and 500 nm) varies with current and temperature. By maintaining a constant junction temperature, the circuit’s electroluminescence is directly affected by a change in current, while a rise in junction temperature influences the light emission at different wavelengths. The work presents an experimental setup that integrates SiC EL with a closed-loop control system to regulate current in a buck converter. Results from the system demonstrate that SiC EL can be used to predict current, providing a basis for future motor drive torque regulation, speed control, and voltage control in power converters. The dissertation also addresses the challenges of low light intensity and nonlinearity in SiC EL measurements, proposing methods to optimize sensitivity and accuracy using avalanche photodetectors and calibration techniques. Despite limitations, such as the weak emission of SiC EL compared to direct bandgap materials, the research establishes a novel and effective approach for current estimation in power electronics applications, paving the way for improved control systems in power conversion and motor drives.

This thesis describes a very high-power density inverter design for a power train that is intended to be used in an all-electric aircraft. The minimum power density for the power electronics for such an aircraft is 50 kW/kg, but this thesis details designs reaching 60 to even 70 kW/kg, even for a multilevel topology inverter. SiC devices were explored in this thesis because wider bandgap materials such as SiC and GaN can operate at higher temperatures, higher power densities, higher voltages, and higher frequencies – making it the most optimal choice for a long-range all-electric aircraft. This thesis also explored numerous multi-inverter topologies to find the most optimal one for the application – ranging from the typical half-bridge to a neutral-point clamped to even a flying capacitor inverter. Thermal calculations were made only for air-cooling; however, future designs aim for liquid cooling for a longer life-time design. Mechanical bus bar work for a prototype and future designs were made on Onshape and presented here. Additional improvements were explored, ranging from incorporating liquid cooling to an extension to soft-switching. A single-phase prototype was made and experimented. The results are presented in this paper. Currently, I am working on improving the prototype with a next iteration of the design, eventually incorporating it with the motor and thermal designs from other projects.