SFBAC PELS is the winner of three awards in 2017: PELS Best Chapter, Region 6 Outstanding Chapter, and SCV Section Outstanding Chapter.
Modeling Transformer Winding Behavior of Multi Output Power Supplies using Mutual Impedance Effects
Bryce Hesterman, Principal Research Engineer, Utah State University
Hosted by the SF Bay Area PELS Society
and co-sponsored by the SCV Chapter IEEE Magnetics Society
|11am - 12pm:||Speaker Presentation and Q&A|
Attendance is free!
Transformer equivalent circuits based on modeling magnetic coupling or mutual inductance describe important aspects of transformer behavior such as leakage inductance and cross regulation. Transformer equivalent circuits based on adding L-R networks typically focus on winding losses predicted by Dowell's method, but they often don't model coupling effects, and they typically don't work well at predicting winding losses for transformers that supply independent loads or for transformers that have windings connected in parallel unless very complicated models are used. This presentation describes an equivalent circuit for transformers that models both magnetic coupling effects and winding losses while using a surprisingly simple structure. The key to this approach is that it is based on mutual impedances that have both inductive and resistive components. This equivalent circuit models the well-known magnetic coupling coefficients, but also models the lesser-known resistance coupling coefficients. This allows the model to accurately model frequency-dependent losses as well as frequency-dependent leakage inductances. The performance of a simulated phase-shifted bridge converter with two independent loads is compared to hardware results. Various effects of mutual impedance are illustrated including cross regulation, how an external ZVS inductor affects the winding losses, and how the frequency dependence of leakage inductances affects diode reverse recovery and the energy that needs to be snubbed.About the Speaker:
Bryce Hesterman is the Principal Research Engineer at the Utah State University Power Electronics Laboratory, which is the headquarters for the NSF Engineering Research Center for Advancing Sustainability through Powered Infrastructure for Roadway Electrification (ASPIRE). He provides advanced engineering support, oversight, and leadership on major research and development projects related to electric transportation. At Aerojet Rocketdyne he designed power electronics for in-space electric propulsion applications such as arc jets, ion engines, and Hall effect thrusters, and was the designated magnetics subject matter expert. At Advanced Energy Industries he designed power converters for applications in the plasma thin film industry such as wafer and CD/DVD metallization, and magnetic coatings on hard drives. He invented or co-invented several soft-switching and resonant power converter topologies used in energy-efficient products, and has been awarded 24 patents. He has authored or co-authored ten technical publications. He enjoys deriving new modeling and simulation techniques, and is now serving as a scientific advisor to Frenetic.ai, an online magnetics design platform. He also enjoys technical writing, hiking and photography. Bryce received BSEE and MSEE degrees from Brigham Young University. He is an active member of IEEE, and formerly served as chair of the Seattle Chapter of the IEEE Power Electronics Society.