Presynopsis Presentations
June 17 2025

Title: Module Power and Loss Balancing through Carrier-reassignment PWM Cascaded H-Bridge Grid-tied Inverters

Abstract:

Access to clean, reliable, and affordable energy is vital for global sustainability, yet grid connectivity remains limited in some regions due to geographical and economic barriers.  Renewable energy sources like solar and wind are critical for combating climate change and enabling sustainable transportation but are inherently unpredictable. Power electronic systems, particularly multilevel inverters (MLIs) like the Cascaded H-Bridge (CHB) topology, are vital for integrating renewables into the grid due to their modularity, scalability, and high-quality waveforms. Conventional level-shifted PWM (LSPWM) causes significant power imbalances in CHB inverters, leading to device stress and premature failure. To address this, three novel carrier-reassignment PWM schemes—Type-A, Type-B, and Type-C—are proposed to enhance power and loss balancing in single-phase grid-connected CHB inverters. These schemes achieve improved power distribution across various power factor conditions, validated through a 9-level and 17-level CHB prototype using closed-loop dq-control in MATLAB/Simulink, Hardware-in-the-Loop (HIL) testing, and PLECS/SPICE thermal models. The results are further verified with a hardware prototype operating in a grid connected mode. The proposed schemes significantly reduce loss disparities, enhance reliability, and improve power quality compared to conventional methods.

Title: Design and Development of Electromagnetic Energy Scavenging System for Transmission Line Inspection Robots

Abstract:

Conventional transmission line inspection methods, such as manual inspection, ground-based observation using telescopes, and aerial surveys employing helicopters or drones, present several drawbacks. These include high operational costs, safety hazards, and limited inspection coverage. To address these challenges, autonomous crawling robots have emerged as a promising alternative. However, powering these mobile systems remains a significant hurdle. Onboard batteries have a limited operational life, while renewable sources like solar energy depend on weather conditions. Capacitive harvesting techniques also demand supplementary infrastructure. This work introduces a design methodology for an electromagnetic energy scavenging system (EMESS) tailored to meet the power requirements of autonomous inspection robots. The EMESS incorporates a split-core current transformer (CT) and a mechanical actuation mechanism, enabling secure and efficient navigation along transmission lines. An optimization approach has been presented here to minimize the mass of split-core CT, thereby enhancing the overall power density of the EMESS. A 70 W, 50 Hz EMESS prototype has been developed utilizing the presented strategy, experimentally tested, and validated through equivalent modeling and finite element analysis. Additionally, the magnetic performance of different soft magnetic material grades—such as cold-rolled non-oriented (CRNO), cold-rolled grain-oriented (CRGO), and amorphous alloys has been comparatively assessed. The influence of mechanical cutting techniques, specifically laser cutting and electrical discharge machining (EDM), on the magnetic behavior of these materials has also been systematically investigated. Finally, a technique is presented to mitigate the electromagnetic force of attraction between core halves at the contact interface during opening and closing operations, enhancing the functional reliability of the EMESS.