Professor Osama A. Mohammed from Florida International University of USA made a presentation - Computational Techniques for the Evaluation and Optimization of Electromagnetic Interference Levels in Multi Component Systems this Monday on Oct 27.
In the presentation, Dr. Mohammed showed modeling details and procedures to quantify signatures and EMI of actual physical components in several practical examples. According to him, detailed physics based computational electromagnetic field models of multi component energy systems enabled the evaluation of realistic waveforms of voltages and currents for low and high frequency operation. These models also enabled inclusion of practical effects such as parasitic elements, leakage saturation, and switching patterns during the system operation. This was essential for studying signatures from individual components and connected systems which were necessary during the design stage. These models also enabled the evaluation of conducted and radiated electromagnetic fields in machinery, cables and power converters used in multi component energy systems. The models enhanced our ability to determine their signatures and EMI interactions as well as evaluated the effectiveness of connecting controllers and/or other components.
Including detailed physical parameters such as geometrical features, material and thermal models in addition to their variation during their dynamic operation, yielded the satisfaction of accurate levels of design objectives which could prove to be useful in devising mitigation strategies such as attenuators and shields. These studies are necessary for product design and for the product to be compliant from EMC point of view.
In multi-scale multi-component system, a number of active and passive components existed and were responsible for the production of unwanted ground currents. The paths to ground allowed low and high frequency currents to close a loop between the components. Grounded connection pointed form paths through high frequency ground capacitors. This current flow between grounding points, of the various components, occurred due to the unbalancing of loading conditions, inter-component fault condition, switching activities and associated harmonics. The high frequency portion of the current due to switching devices coupled the control circuits through low-voltage low-current elements and negatively affected the operation of the system.
From an electromagnetic signature point of view, the low and high frequency currents form loops passing this current and the resulting electromagnetic field would radiate in the surrounding environment. Any current loop with either DC or AC currents in the operational system would cause signature issues. If the amplitude of current was large enough to produce detectable field, the signatures must be evaluated for specific applications in order to develop mitigation strategies.
Dr. Mohammed is a Professor of Electrical Engineering and the Director of the Energy Systems Research Laboratory at Florida International University, Miami, Florida. He received his Master and Doctoral degrees in Electrical Engineering from Virginia Tech in 1981 and 1983, respectively. He has performed research on various topics in power and energy systems in addition to computational electromagnetics and design optimization in electric machines, electric drive systems and other low frequency environments. He performed multiple research projects for several Federal agencies since 1990’s dealing with; power system analysis, physics based modeling, electromagnetic signature, sensorless control, electric machinery, high frequency switching, electromagnetic Interference and ship power systems modeling and analysis. Professor Mohammed has currently active research programs in a number of these areas. Professor Mohammed is a world renowned leader in electrical energy systems and computational electromagnetics. He has published more than 400 articles in refereed journals and other IEEE refereed International conference records. Professor Mohammed is an elected Fellow of IEEE and is an elected Fellow of the Applied Computational Electromagnetic Society. Professor Mohammed is the recipient of the prestigious IEEE Power and Energy Society Cyril Veinott electromechanical energy conversion award and the 2012 outstanding research award from Florida International University.
