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Regression Techniques for Parameter Estimation of a Synchronous Machine from Sudden Short-Circuit Testing

US Air Force-Kevin J. Yost
P.C. Krause And Associates Inc.-Brett A. Robbins, Will Perdikakis
Published 2019-03-19 by SAE International in United States
A sudden short-circuit (SSC) laboratory test of an electric machine is a commonly used procedure to estimate model parameters that accurately represent the dynamic response of the machine. While the graphical interpretation of the short-circuit current is often discussed in great detail, the numerical methods used to determine the solution for the machine parameter estimation is a challenging proposition. In this paper, the authors present an integral regression technique to fit the characteristic equation of the short-circuit current to a curve that is composed of exponential decays that trail off to an unknown steady-state value in the presence of noise. The proposed estimation method is applied to laboratory data from an aerospace synchronous machine.
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Power Quality Assessment through Stochastic Equivalent Circuit Analysis

SAE International Journal of Aerospace

US Air Force-Chad Miller
Air Force Research Lab-Jane Thompson
  • Journal Article
  • 2016-01-1988
Published 2016-09-20 by SAE International in United States
Movement toward more-electric architectures in military and commercial airborne systems has led to electrical power systems (EPSs) with complex power flow dynamics and advanced technologies specifically designed to improve power quality in the system. As such, there is a need for tools that can quickly analyze the impact of technology insertion on the system-level dynamic transient and spectral power quality and assess tradeoffs between impact on power quality versus weight and volume. Traditionally, this type of system level analysis is performed through computationally intensive time-domain simulations involving high fidelity models or left until the hardware fabrication and integration stage. In order to provide a more rapid analysis prior to hardware development and integration, stochastic equivalent circuit analysis is developed that can provide power quality assessment directly in the frequency domain.Stochastic equivalent circuit analysis calculates network voltage probability distribution utilizing stochastic equivalent circuits assembled into a candidate power system. Utilization of stochastic equivalent circuits allows for rapid analysis of the electric power system under different configurations where the effect of device insertion/removal on power quality is…
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Utilizing Behavioral Models in Experimental Hardware-in-the-Loop

SAE International Journal of Aerospace

US Air Force-Chad N. Miller
PC Krause & Associates-Michael Boyd
  • Journal Article
  • 2016-01-2042
Published 2016-09-20 by SAE International in United States
This paper introduces a method for conducting experimental hardware-in-the-loop (xHIL), in which behavioral-level models are coupled with an advanced power emulator (APE) to emulate an electrical load on a power generation system. The emulator is commanded by behavioral-level models running on an advanced real-time simulator that has the capability to leverage Central Processing Units (CPUs) and field programmable gate arrays (FPGA) to meet strict real-time execution requirements. The paper will be broken down into four topics: 1) the development of a solution to target behavioral-level models to an advanced, real-time simulation device, 2) the development of a high-bandwidth, high-power emulation capability, 3) the integration of the real-time simulation device and the APE, and 4) the application of the emulation system (simulator and emulator) in an xHIL experiment. The first topic will be addressed by targeting a behavioral-level model of a brushless dc motor drive with a pulse-width modulated inverter to a real-time simulator. The results of the real-time model will be compared to that of its non-real-time counterpart. For the second topic, hardware descriptions and…
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Hybrid Technique for Real-Time Simulation of High-Frequency-Switched Electrical Systems

SAE International Journal of Aerospace

US Air Force-Jon Zumberge, Chad Miller
PC Krause & Associates-Maher A. Hasan, Eric Walters, Michael Boyd, Jason Wells
  • Journal Article
  • 2016-01-2028
Published 2016-09-20 by SAE International in United States
Experimental Hardware-in-the-loop (xHIL) testing utilizing signal and/or power emulation imposes a hard real-time requirement on models of emulated subsystems, directly limiting their fidelity to what can be achieved in real-time on the available computational resources. Most real-time simulators are CPU-based, for which the overhead of an instruction-set architecture imposes a lower limit on the simulation step size, resulting in limited model bandwidth. For power-electronic systems with high-frequency switching, this limit often necessitates using average-value models, significantly reducing fidelity, in order to meet the real-time requirement. An alternative approach emerging recently is to use FPGAs as the computational platform, which, although offering orders-of-magnitudes faster execution due to their parallel architecture, they are more difficult to program and their limited fabric space bounds the size of models that can be simulated. This paper presents a new method for simulating detailed models of power-electronic systems in real-time, targeting simulation platforms that combine both FPGAs and CPUs, but can also be adapted to run on multi-CPU systems. The method creates a multi-rate model by decomposing simulation process into discrete…
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The Utility of Wide-Bandwidth Emulation to Evaluate Aircraft Power System Performance

SAE International Journal of Aerospace

US Air Force-Jon Zumberge
PC Krause & Associates-Michelle Bash
  • Journal Article
  • 2016-01-1982
Published 2016-09-20 by SAE International in United States
The cost and complexity of aircraft power systems limit the number of integrated system evaluations that can be performed in hardware. As a result, evaluations are often performed using emulators to mimic components or subsystems. As an example, aircraft generation systems are often tested using an emulator that consists of a bank of resistors that are switched to represent the power draw of one or more actuators. In this research, consideration is given to modern wide bandwidth emulators (WBEs) that use power electronics and digital controls to obtain wide bandwidth control of power, current, or voltage. Specifically, this paper first looks at how well a WBE can emulate the impedance of a load when coupled to a real-time model. Capturing the impedance of loads and sources is important for accurately assessing the small-signal stability of a system. Secondly, this paper demonstrates the merits of a WBE for characterizing aircraft sources and loads to identify key performance parameters. The parameters can then be plugged into a simplified model that is used in simulation to identify stability…
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Development and Performance of a Reduced Order Dynamic Aircraft Model

US Air Force-Robert A. Reuter, Steven Iden
PC Krause & Associates-Kyle Shimmin, Greg Russell
Published 2015-09-15 by SAE International in United States
A reduced order dynamic aircraft model has been created for the purpose of enabling constructive simulation studies involving integrated thermal management subsystems. Such studies are motivated by the increasing impact of on-board power and thermal subsystems to the overall performance and mission effectiveness of modern aircraft. Previous higher-order models that have been used for this purpose have the drawbacks of much higher development time, along with much higher execution times in the simulation studies. The new formulation allows for climbs, accelerations and turns without incurring computationally expensive stability considerations; a dynamic inversion control law provides tracking of user-specified mission data. To assess the trade-off of improved run-time performance against model capability, the reduced order formulation is compared to a traditional six degree-of-freedom model of the same air vehicle. Thrust command comparisons against the higher fidelity model are shown to be excellent when the aerodynamics is properly conditioned, and a methodology for transforming existing higher-order models into the new formulation is suggested. It is believed that the present air vehicle plant model and its associated controller…
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Enhancements to Software Tools and Progress in Model-Based Design of EOA on the INVENT Program

US Air Force-Peter T. Lamm
Boeing Research & Technology-David McCormick, Paul Pigg
Published 2014-09-16 by SAE International in United States
The diverse and complex requirements of next-generation energy optimized aircraft (EOA) demand detailed transient and dynamic model-based design (MBD) to ensure the proper operation of numerous interconnected and interacting subsystems across multiple disciplines. In support of the U.S. Air Force's Integrated Vehicle Energy Technology (INVENT) program, several MBD-derived software tools, including models of EOA technologies, have been developed. To validate these models and demonstrate the performance of EOA technologies, a series of Integrated Ground Demonstration (IGD) hardware tests are planned. Several of the numerous EOA software tools and MBD-based processes have been updated and adapted to support this activity. In this paper, the following key enhancements to the INVENT software tools and the MBD process are discussed: distributed version control; batch launch capability for co-simulation software; automated test script (ATS) library upgrades; and data visualization tool enhancements. For each, details are given about the motivation behind, and the implementation of, the enhancement. The described improvements reduce the potential for MBD errors and design cycle time and allow for a greater number of IGD experiments to…
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Model Validation Planning and Process on the INVENT Program

US Air Force-Peter T. Lamm
Boeing Research & Technology-David McCormick, Paul Pigg
Published 2014-09-16 by SAE International in United States
Validation is a critical component of model-based design (MBD). Without it, regardless of the level of model verification, neither the accuracy nor the domain of applicability of the models is known. Thus, it is risky to base design decisions on the predictions of unvalidated models. The Integrated Vehicle Energy Technology (INVENT) program is planning a series of hardware experiments that will be used to validate a large set of unit-, subsystem-, and system-level models. Although validating such a large number of interacting models is a large task, it provides an excellent opportunity to test the limits of MBD. For INVENT, a Verification and Validation Plan (VVP) has been created to implement many relevant aspects of both verification and validation: it describes several methods and approaches, identifies roles and responsibilities for the diverse group of team members, specifies the process flow to be followed by the team, provides reporting standards for each step in the process flow, and suggests ways to determine the level of model validation required depending on the model purpose. This paper describes…
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Developing IVHM Requirements for Aerospace Systems

US Air Force-J.B. Schroeder
Airbus Operations GmbH-Frank Kramer
Published 2013-09-17 by SAE International in United States
The term Integrated Vehicle Health Management (IVHM) describes a set of capabilities that enable sustainable and safe operation of components and subsystems within aerospace platforms. However, very little guidance exists for the systems engineering aspects of design with IVHM in mind. It is probably because of this that designers have to use knowledge picked up exclusively by experience rather than by established process. This motivated a group of leading IVHM practitioners within the aerospace industry under the aegis of SAE's HM-1 technical committee to author a document that hopes to give working engineers and program managers clear guidance on all the elements of IVHM that they need to consider before designing a system. This proposed recommended practice (ARP6883 [1]) will describe all the steps of requirements generation and management as it applies to IVHM systems, and demonstrate these with a “real-world” example related to designing a landing gear system. The team hopes that this paper and presentation will help start a dialog with the larger aerospace community and that the feedback can be used to…
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Refrigerant Charge Management and Control for Next-Generation Aircraft Vapor Compression Systems

US Air Force-Thomas Reitz
US Air Force Research Laboratory-Anthony Puntel, Travis E. Michalak, Larry Byrd
Published 2013-09-17 by SAE International in United States
Vapor compression systems (VCS) offer significant benefits as the backbone for next generation aircraft thermal management systems (TMS). For a comparable lift, VCS offer higher system efficiencies, improved load temperature control, and lower transport losses than conventional air cycle systems. However, broad proliferation of VCS for many aircraft applications has been limited primarily due to maintenance and reliability concerns. In an attempt to address these and other VCS system control issues, the Air Force Research Laboratory has established a Vapor Cycle System Research Facility (VCSRF) to explore the practical application of dynamic VCS control methods for next-generation, military aircraft TMS.The total refrigerant mass contained within the closed refrigeration system (refrigerant charge) is a critical parameter to VCS operational readiness. Too much or too little refrigerant can be detrimental to system performance. Extreme values of refrigerant charge can lead to a loss of evaporator temperature control, loss of high side pressure control, or other potentially catastrophic occurrences. The objective of this work is to examine real-time methods for determination of acceptable refrigerant charge in a prototypical…
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