Engineering Commons^™

Nonlinear Parameter Estimation Of Excitation Systems, Rajeev Bhaskar, Mariesa Crow, Eric Ludwig, Kelvin T. Erickson, Kirit S. Shah

Electrical and Computer Engineering Faculty Research & Creative Works

This paper details the nonlinear parameter estimation process of an IEEE AC1A type exciter using time-domain system identification techniques. This paper discusses nonlinear parameter estimation techniques, systematic and random noise mitigation strategies, and system validation. This study establishes a strong basis for excitation system parameter estimation.

Voltage Stability Analysis: V-Q Power Flow Simulation Versus Dynamic Simulation, Badrul H. Chowdhury, C. W. Taylor

Electrical and Computer Engineering Faculty Research & Creative Works

Several analysis methods are available for long-term voltage stability. The V-Q curve power flow method is widely used by Western Systems Coordinating Council utilities, and has some advantages. Long-term dynamic simulation with proper modeling, however, is clearly the most accurate simulation method. The authors compare the two methods for wintertime voltage stability problems in the Portland, Oregon, USA, load area. Results from the V-Q method can be misleading. The same is true of other power flow program based analysis employing conventional modeling. Results from these power flow methods may be pessimistic, causing overdesign or overly conservative operation.

Laboratories Teaching Concepts In Microcontrollers And Hardware-Software Co-Design, Daryl G. Beetner, Hardy J. Pottinger, Kyle Mitchell

Electrical and Computer Engineering Faculty Research & Creative Works

Hardware software co-design is becoming increasingly important to the embedded systems industry. It will soon be fundamental to digital systems design. As such, students in electrical and computer engineering and in computer science should be introduced to hardware-software co-design early in their undergraduate education.

We are designing laboratory modules which introduce concepts of hardware-software co-design in an undergraduate's first course on microcontrollers and digital systems design. Students use design automation tools to develop FPGA-based hardware for use with an 8051-microcontroller and use common software development tools to develop microcontroller software in C or assembly language. Co-simulation of hardware and software …

Dc Power Bus Modeling Using A Circuit Extraction Approach Based On A Mixed-Potential Integral Equation Formulation And An Iterative Equation Solver, Jun Fan, James L. Drewniak, James L. Knighten

Electrical and Computer Engineering Faculty Research & Creative Works

A quick and simple approach is developed to perform circuit simulations for an equivalent circuit extracted from a first principles formulation for DC power bus structures. The simulations are done by solving the system equation using an iterative method. Good agreement between modeling and measurements demonstrate the effectiveness of the method, which is very suitable and computationally efficient for frequency-domain DC power modeling.

Statcom Control For Power System Voltage Control Applications, Pranesh Rao, Zhiping Yang, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

A static compensator (STATCOM) is a device that can provide reactive support to a bus. It consists of voltage sourced converters connected to an energy storage device on one side and to the power system on the other. In this paper the conventional method of PI control is compared and contrasted with various feedback control strategies. A linear optimal control based on LQR control is shown to be superior in terms of response profile and control effort required. These methodologies are applied to an example power system

Dc Power Bus Design With Fdtd Modeling Including A Dispersive Media, Xiaoning Ye, Jun Fan, Marina Koledintseva, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

DC power-bus modeling in high-speed digital design using the FDTD method is reported here. The dispersive medium is approximated by a Debye model to account for the loss. A wide band frequency response (100 MHz-5 GHz) is obtained through a single FDTD simulation. Favorable agreement is achieved between the modeled and measured results for a typical DC power-bus structure with multiple SMT decoupling capacitors mounted on the board. The FDTD tool is then applied to investigate the effects of local decoupling on a DC power-bus. The modeled results agree with the results from another modeling tool, the CEMPIE (a circuit …

Performance Monitoring In Umr's Solar Car, Louis Mccarthy, Josh Pieper, Aaron Rues, Cheng-Hsiao Wu

Electrical and Computer Engineering Faculty Research & Creative Works

We describe the instrumentation in UMR's solar car. Accurate knowledge of the operating parameters inside the solar car is shown to be crucial to maintaining high efficiency and reliability. The power trackers keep the solar array operating at its highest efficiency by conditioning the input and maintaining the maximum power point of the solar cells.

Process Modeling, Monitoring And Control Of Laser Metal Forming, N. Munjuluri, Sanjeev Agarwal, Frank W. Liou

Electrical and Computer Engineering Faculty Research & Creative Works

Laser Metal Forming (LMF) process is one of the prominent Rapid Prototyping (RP) process that can be used to develop functional and fully dense metal parts. This paper addresses process modeling, monitoring and control of a laser metal forming system currently under development at Laser Aided Manufacturing Processes (LAMP) laboratory at University of Missouri--Rolla. This LMF system is based on a 2.5kW Nd:YAG laser as energy source and integrates five axis metal deposition and five axis machining. The current paper is aimed at characterization of effects of operating parameters such as traverse speed, mass flow-rate and laser power on the …

Experimental And Fdtd Study Of The Emi Performance Of An Open-Pin-Field Connector For Modules-On-Backplanes, Xiaoning Ye, Jim Nadolny, James L. Drewniak, Richard E. Dubroff, Thomas Van Doren, Todd H. Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

Experimental measurements and numerical modeling were used to study the EMI performance of a module-on-backplane connector for various configurations of signal-return pin-outs. A commercially available open-pin-field connector was used in these results to connect between the mother-board and the daughter-card. The experimental techniques, based on measuring |S₂₁|, included both common-mode current measurements and monopole near-field probe measurements. The FDTD method was used to provide numerical support of the near-field measurements and generally agreed with the measured results for frequencies up to 3 GHz. The FDTD method was also used to investigate the relationship between the radiated EMI at …

Experimental And Numerical Study Of The Radiation From Microstrip Bends, H. Wang, Yun Ji, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

This paper investigates the radiation from microstrip lines with 90-degree bends. A 1-GHz TEM cell is used to measure the radiation from microstrip lines with different kinds of bends. A full wave hybrid FEM/MoM code is used to compute the radiation. Both experimental and numerical results show that there is no significant difference between the radiation from right angle bends and bends with two 45-degree corners at frequencies and trace dimensions that are likely to be found on printed circuit boards.

Experimental Evaluation Of Power Bus Decoupling On A 4-Layer Printed Circuit Board, Juan Chen, Minjia Xu, Todd H. Hubing, James L. Drewniak, Thomas Van Doren, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The switching of active devices on printed circuit boards (PCBs) can cause a momentary surge or drop in the power bus voltage. Decoupling capacitors are often utilized to alleviate this problem. They help to stabilize the power bus voltage by supplying transient current to active devices. The decoupling strategy, including where to place the high-frequency decoupling capacitors, is often a topic of debate. This paper examines the effect of decoupling capacitor placement on a 4-layer printed circuit board. Some design guidelines are provided.

Emi From Airflow Aperture Arrays In Shielding Enclosures-Experiments, Fdtd, And Mom Modeling, Min Li, Joe Nuebel, James L. Drewniak, Richard E. Dubroff, Todd H. Hubing, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Aperture arrays designed to provide airflow through shielding enclosures can provide part of the coupling path from interior sources to external electromagnetic interference (EMI). In this work, radiation through aperture arrays is investigated numerically and experimentally. FDTD modeling is compared with measurements on aperture arrays in a test enclosure. The method of moments (MoM) is also utilized to study radiation from apertures and to investigate the mutual coupling between apertures in an infinite conducting plane. A simple design equation for the relation between aperture size and number and shielding effectiveness is proposed.

Fdtd And Fem/Mom Modeling Of Emi Resulting From A Trace Near A Pcb Edge, Daniel P. Berg, Motoshi Tanaka, Yun Ji, Xiaoning Ye, James L. Drewniak, Todd H. Hubing, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

PCB traces routed near board edges and carrying high-speed signals are considered to contribute to EMI problems. Consequently, design maxims state that traces that might have intentional or unintentional high frequency components on them be kept away from board edges. This costs valuable surface area as boards become more densely designed. Further, design maxims concerning traces near board edges are not well quantified. The increase in EMI as a trace is routed increasingly closer to the PCB edge has been studied experimentally and with numerical modeling.

Finite Element Modeling Of Patch Antenna And Cavity Sources, Yun Ji, Todd H. Hubing, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

This paper examines two different approaches that can be used to model patch antennas and cavities fed by a coaxial cable. The probe model represents the feed as a current filament along the center conductor of the coaxial cable. The coaxial-cable model enforces the analytical field distribution at the cable opening. These two models have been implemented in a hybrid FEM/MoM code. A power bus structure and a cavity geometry with coaxial-cable feeds are investigated. Numerical results obtained for these two examples are compared with measurements. It is shown that the probe model should only be applied to electrically short …

Development Of A Closed-Form Expression For The Input Impedance Of Power-Ground Plane Structures, Minjia Xu, Yun Ji, Todd H. Hubing, Thomas Van Doren, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

This paper analyzes the fundamental behavior of PCB power bus structures using the modal expansion method. The results are validated by experiments and full-wave numerical modeling. It is shown that the power bus can be modeled as a series L_eC circuit below the first board resonance frequency. C is the interplane capacitance and L_e is an effective inductance contributed by all the cavity nodes. The effects of the layer thickness, port location, board size and the feeding wire radius on the value of L_e are discussed in this study. L_e can be estimated from the …

Emc Analysis Of An 18" Lcd Monitor, Theodore M. Zeeff, Todd H. Hubing, James L. Drewniak, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

This paper describes a case study covering the evaluation and reduction of the radiated EMI from an 18 inches Liquid Crystal Display (LCD) monitor. The evaluation was completed in two parts: first potential EMI sources at the Printed Circuit Board (PCB) level were identified, then the EMI antennas driven by these sources were analyzed. Methods for reducing the EMI were described in detail, and where applicable, those modifications were applied. Radiated measurements demonstrate the effectiveness of these recommendations.

Quantifying Decoupling Capacitor Location, Jun Fan, James L. Knighten, Antonio Orlandi, Norman W. Smith, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Decoupling capacitor location in DC power bus design is a critical design choice for which proven guidelines are not well established. The mutual inductance between two closely spaced vias can have a great impact on the coupling between an IC and a decoupling capacitor. This coupling is a function of the spacing between the IC and capacitor, and spacing between power and ground layers. The impact of the mutual inductance on decoupling, i.e., local versus global decoupling, was studied, using a circuit extraction approach based on a mixed-potential integral equation. Modeling indicates that local decoupling has benefits over global decoupling …

The Emi Benefits Of Ground Plane Stitching In Multi-Layer Power Bus Stacks, Xiaoning Ye, David M. Hockanson, Min Li, Wei Cui, S. Radu, James L. Drewniak, Thomas Van Doren, Todd H. Hubing, Richard E. Dubroff

Electrical and Computer Engineering Faculty Research & Creative Works

The effect on EMI of stitching multiple ground planes together along the periphery of multi-layer PCB stacks is studied. Power bus noise induced EMI and radiation from the board edges is the major concern herein. The EMI at 3 meters for different via stitch spacing and layer thickness is modeled with FDTD modeling. It is shown that the ground plane stitching effectively reduces the radiated EMI that results from fringing fields at the power bus edges. Two families of curves are generated to demonstrate the variation of the radiated EMI as a function of layer thickness and stitch spacing. Further …

An Improved Statcom Model For Power Flow Analysis, Zhiping Yang, Chen Shen, Lingli Zhang, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

The StatCom is traditionally modeled for power flow analysis as a PV or PQ bus depending on its primary application. The active power is either set to zero (neglecting the StatCom losses) or calculated iteratively. The StatCom voltage and reactive power compensation are usually related through the magnetics of the StatCom. This traditional power flow model of the StatCom neglects the impact of the high-frequency effects and the switching characteristics of the power electronics on the active power losses and the reactive power injection (absorption). In this paper, the authors propose a new StatCom model appropriate for power flow analysis …

Role Of Laboratory Education In Power Engineering: Is The Virtual Laboratory Feasible? Part I, S. Iwamoto, G. G. Karady, Kraig J. Olejniczak, H. A. Mantooth, Mariesa Crow, Gerald T. Heydt

Electrical and Computer Engineering Faculty Research & Creative Works

IEEE PES sponsors a panel session in the summer power meeting in Seattle on laboratory education in power engineering. Six short papers and one full paper summarize the opinions of the panelist. This paper contains the summary of four of the presentations. The objective of the panel is to discuss the role of laboratory education in power engineering at both the graduate and undergraduate level. The question is what type of laboratory course is needed? Power electronics, electric machines, system simulation, etc? the second objective is to assess the status and value of computer based virtual laboratories. This includes the …

Dc Power Bus Modeling In High-Speed Digital Designs Including Conductor And Dielectric Losses, Jun Fan, Hao Shi, James L. Knighten, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Power bus design is a critical aspect in high-speed digital circuit designs. A circuit extraction approach based on a mixed-potential integral equation formulation is presented herein to model arbitrary multilayer power bus structures including vertical discontinuities associated with surface mount (SMT) decoupling capacitor interconnects. Both conductor and dielectric losses are incorporated, and included into the first principles formulation. The agreement of modeling and measurements demonstrates its effectiveness and utilization in power bus designs.

Fdtd Modeling Of Lumped Ferrites, Min Li, Xiao Luo, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Implementing ferrites in finite-difference time-domain (FDTD) modeling requires special care because of the complex nature of the ferrite impedance. Considerable computational resources and time are required to directly implement a ferrite in the FDTD method. Fitting the ferrite impedance to an exponential series with the generalized-pencil-of-function (GPOF) method and using recursive convolution is an approach that minimizes the additional computational burden. An FDTD algorithm for a lumped ferrite using GPOF and recursive convolution is presented herein. Two different ferrite impedances in a test enclosure were studied experimentally to demonstrate the FDTD modeling approach. The agreement is generally good.

Emi Reduction From Airflow Aperture Arrays Using Dual-Perforated Screens And Loss, Min Li, Joe Nuebel, James L. Drewniak, Todd H. Hubing, Richard E. Dubroff, Thomas Van Doren

Electrical and Computer Engineering Faculty Research & Creative Works

Airflow perforations in shielding enclosures can act as apertures facilitating the coupling from internal sources to external electromagnetic interference (EMI). This EMI radiation for single- and dual-screen configurations was studied herein experimentally and with finite-difference time-domain (FDTD) modeling. A general EMI reduction of more than 20 dB was achieved for dual-perforated screens spaced 1 cm apart when compared to EMI for a single perforated screen. However, in the dual-screen case, the space between the screens can act as a thin cavity, which, in turn, can lead to significant radiation at distinct angles. Damping the resonances by loading the space between …

Emi Resulting From A Signal Via Transition Through Dc Power Bus-Effectiveness Of Focal Smt Decoupling, Wei Cui, Xiaoning Ye, Bruce Archambeault, Doug White, Min Li, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Signal vias are commonly used in multilayer printed circuit board (PCB) design. For a signal via transitioning through the internal power and ground planes, the return current has to jump from one reference plane to another reference plane. The discontinuity of the return current at the via excites the power and ground planes, and results in power bus noise, and can produce an EMI problem as well. Numerical methods, such as finite-difference time-domain (FDTD), moment methods (MoM), and partial element equivalent circuit (PEEC), were employed herein to study this problem. The modeled results were supported by the measurements. In addition, …

A Common-Mode Current Measurement Technique For Emi Performance Evaluation Of Pcb Structures, Xiaoning Ye, David M. Hockanson, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

An experimental technique that measures the common-mode current on a cable attached to a DUT for assessing EMI performance is introduced herein. The technique was applied to evaluate the EMI performance of a module-on-backplane configuration with different connectors and different connector pin-outs.

Modeling Emi Resulting From A Signal Via Transition Through Power/Ground Layers, Wei Cui, Xiaoning Ye, Bruce Archambeault, Doug White, Min Li, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

Signal transitioning through layers on vias are very common in multi-layer printed circuit board (PCB) design. For a signal via transitioning through the internal power and ground planes, the return current must switch from one reference plane to another reference plane. The discontinuity of the return current at the via excites the power and ground planes, and results in noise on the power bus that can lead to signal integrity, as well as EMI problems. Numerical methods, such as the finite-difference time-domain (FDTD), Moment of Methods (MoM), and partial element equivalent circuit (PEEC) method, were employed herein to study this …

Emi Model Validation And Standard Challenge Problems, Bruce Archambeault, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A joint effort of the IEEE/EMC Society TC-9 Committee and the Applied Computational Electromagnetic Society (ACES) resulted in a central web location for contributors who will provide model and measurement data to share and compare with others. In addition to the data repository, a set of standard challenge problems have been proposed over the past few years, and are located at the web site. The site will be carefully monitored by a review committee to insure only high-quality information is posted on the site.

Behavioral Igbt Modeling For Predicting High Frequency Effects In Motor Drives, Jerry L. Tichenor, S. D. Sudhoff, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A first-order behavioral IGBT/gate drive model is proposed together with a procedure for deriving all model parameters. Despite the simplicity of the proposed model, comparison of model predictions with hardware measurements demonstrate the model to be accurate in predicting turn-on and turn-off transients.

Collaborative Distance Education In Power Engineering, Anil Pahwa, Shelli K. Starrett, Kraig J. Olejniczak, S. D. Sudhoff, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a perspective on offering "shared-courses," or courses simultaneously offered at two or more universities via various distance educational frameworks. Over a three year duration, two senior/graduate level courses were jointly developed and offered to the students at the University of Missouri--Rolla, the University of Arkansas, Kansas State University, and Purdue University. This paper discusses the various distance educational technologies including two-way audio/visual via ISDN line, video-tapes, and web-based conferencing. Both instructor and student reactions to these mediums are included. Pedagogical methods appropriate for these mediums are outlined. The paper concludes with recommendations and strategies for engineering institutions …

Microwave Near-Field Reflection Property Analysis Of Concrete For Material Content Determination, Karl Joseph Bois, Aaron D. Benally, R. Zoughi

Electrical and Computer Engineering Faculty Research & Creative Works

One of the most important parameters associated with concrete is its compressive strength. Currently, there is no reliable nondestructive testing technique that is capable of robust determination of this parameter. Concrete is a heterogeneous mixture composed of water, cement powder, sand (fine aggregate), rocks of various size or grade (coarse aggregate), and air (porosity). Water and cement powder chemically combine into a cement paste binder which, in due curing time (28 days), produces concrete with its specified compressive strength. Compressive strength of concrete is strongly influenced by its water-to-cement (w/c) ratio as well as its coarse aggregate-to-cement (ca/c) ratio. Therefore, …