overview of circuit simulation programs ece 546 digital computational techniques for electronic...
TRANSCRIPT
Overview of Circuit Simulation Programs
ECE 546 DIGITAL COMPUTATIONAL TECHNIQUES FOR ELECTRONIC CIRCUITS
January 8, 2008
Oleg Wasynczuk
Need for System-of-Subsystems Approach
Complex engineered systems such as aircraft, modern automobiles, or the terrestrial electric power grid involve a broad spectrum of technologies and interactive subsystems that must work synergistically in order to operate properly
Inter-dependencies between subsystems are becoming more and more prominent
More-Electric Aircraft Power System
Modeling Approaches
Synchronous Machine Subsystem Models
Distributed Parameter Coupled Circuit Steady State
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Simulation Approaches
Circuit-Based Approaches (Spice, EMTP, Saber, PSIM, Simplorer)
System-Based Approaches (Simulink, ACSL, Dymola) Block-diagram and/or differential equation oriented Extensive set of tool boxes including
ASMG (Simulink, ACSL) Power System Blockset (Simulink) …
Finite-Element-Based Approaches (Ansys, Maxwell, …)
Circuit-Based Approaches
Circuit-Based Approaches
Example Subsystem
(Motor Controller)
Circuit-Based Approaches
Circuit-Based Approaches
Resistor-Companion Circuit
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Update Formula
O(n3) computational complexity where n = number of non-datum nodes
Circuit-Based Approaches
Simulation Approaches
Circuit-Based Approaches (Spice, Saber, PSIM, Simplorer)
System-Based Approaches (Simulink, ACSL, Dymola) Block-diagram and/or differential equation oriented Extensive set of tool boxes including
ASMG (Simlink, ACSL) Power System Blockset (Simulink) …
Finite-Element-Based Approaches (Ansys, Maxwell, …)
System-Based Approaches
Hierarchical system definition
System-Based Approaches
Common Simulink Component Models
System-Based Approaches
System-Based Approaches
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When user starts model, Simulink applies selected integration algorithm to approximate solution at discrete but not necessarily uniform instants of time
General Multi-step Formula
Implicit algorithms require solution of nonlinear equation (dimension = number of states) at each time step. Newton-Raphson iteration generally used.
Explicit if 01
System-Based Approaches
Stiff System: A system with both fast and slow dynamics
Stiffly Stable Integration Algorithm: the ability to increase the time step after fast transients subside
Stiffly Stable Algorithms are implicit!
System-Based Approaches
Computational Complexity
System-Based Approaches
Dilemma
Simulink Algorithms
Shampine and Reichelt, The MATLAB ODE Suite, SIAM J. Sci. Comput.,Vol. 18, No. 1, pp. 1-22, January 1997.
System-Based Approaches
Simulation Approaches
Circuit-Based Approaches (Spice, Saber, PSIM, Simplorer)
System-Based Approaches (Simulink, ACSL, Dymola) Block-diagram and/or differential equation oriented Extensive set of tool boxes including
ASMG (Simulink, ACSL) Power System Blockset (Simulink) …
Finite-Element-Based Approaches (Ansys, Maxwell, …)
Finite-Element Based Approaches
4000-10000 Nodes
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Conventional Parallel Computing Paradigm
Conventional Parallel Computing Paradigm
Conventional Parallel Computing Paradigm
Conventional Parallel Computing Paradigm
At best m-fold reduction in computation time assuming zero communication latency
Computational gain further bounded by Amdahl’s Law
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Distributed Heterogeneous Simulation (DHS)
DHS Definition
Synchronized interconnection of any number of dynamic subsystem simulations
Developed using any combination of programs/languages
Implemented on:• Single computer/workstation/supercomputer• Local area network (Intranet)• Wide area network (Internet)
Sample DHS Computer Setup
DHS Concept
Much better than M-fold (potentially M3) improvement in speed
DHS Links Environment
Flexibility of DHS
Heterogeneous platforms (Windows, Unix, Linux, ...) Heterogeneous languages (ACSL, MATLAB/Simulink,
Saber, EASY5, C, C++, FORTRAN, Java,…) Heterogeneous simulation approaches (single-rate, multi-
rate, state model based, resistor-companion, finite difference/element,...)
Heterogeneous networks (Ethernet, SCI, ScramnetTM, MyrinetTM,...)
Use “best” language for each component/subsystem Proprietary information protected Super-linear increase in computational speed across a network
of desktop computers No need to translate models into common language Legacy code can be used directly Conducive to team design/analysis Remote interconnection Eliminate need to develop average-value models for system
stability assessment Real-time (hardware-in-the-loop) capability for some systems System Integrator(s) do not have to be familiar with the
language(s) used to create subsystem simulation(s)
Key Advantages of DHS
More-Electric Aircraft Power System
Optimum Allocation
Optimum Allocation
Optimum Allocation
18.5 speedup with 4 computers