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QRCode Reader In None Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications. Make QR Code In C#.NET Using Barcode drawer for .NET Control to generate, create QR Code image in .NET applications. to accomplish this task. The time step is increased after the event, until the next cycle, when it is again reduced. This time step hysteresis can cause an excessive number of unnecessary calculations. To correct this problem, we can regress to a SPICE 2 methodology and force the simulator to have a xed time step value. To force the time step to be a xed value, set the TRTOL value to 25, i.e., .OPTIONS TRTOL =25. The default value is 7. The Trtol parameter controls how far ahead in time SPICE tries to jump. The value of 25 causes PSpice to try to jump far ahead. Then set TMAX (maximum allowed time step) in the .TRAN statement to a value that is between 1/10 and 1/100 of the switching cycle period. This has the opposite effect; it forces the time step to be limited. Together, they effectively lock the simulator time step to a value that is between 1/10 and 1/100 of the switching cycle period and eliminate virtually all of the rejected time points. These settings can result in over a 100% increase in speed! Note: In order to verify the number of accepted and rejected time points, you may issue the .OPTIONS ACCT parameter and view the summary data at the end of the output le. If this does not help the simulation converge, proceed to the next section that has more details. Simulation Convergence The answer to a nonlinear problem, such as those in the SPICE DC and transient analyses, is found via an iterative solution. For example, PSpice makes an initial guess at the circuit s node voltages and then, using the circuit conductances, calculates the mesh currents. The currents are then used to recalculate the node voltages, and the cycle begins again. This continues until all the node voltages settle to values that are within speci c tolerance limits. These limits can be altered using various .OPTIONS parameters such as RELTOL, VNTOL, and ABSTOL. If the node voltages do not settle down within a certain number of iterations, the DC analysis will issue an error message such as No convergence in DC analysis, Singular matrix, GMIN stepping failed, or Source stepping failed. PSpice will then halt the run because both the AC and transient analyses require an initial stable operating point in order to proceed. During the transient analysis, this iterative process is repeated for each individual time step. If the node voltages do not settle down, the time step is reduced and PSpice tries again to determine the node voltages. If the time step is reduced beyond a speci c fraction of the total analysis time, the transient analysis will issue the error message Time step too small, and the analysis will be halted. Convergence problems come in all shapes, sizes, and disguises, but they are usually related to one of the following: Quick Response Code Generator In .NET Using Barcode encoder for ASP.NET Control to generate, create QR Code 2d barcode image in ASP.NET applications. QR Creator In .NET Framework Using Barcode encoder for .NET Control to generate, create Quick Response Code image in .NET framework applications. Solving Convergence and Other Simulation Problems
QR Code JIS X 0510 Drawer In VB.NET Using Barcode generator for Visual Studio .NET Control to generate, create QR Code 2d barcode image in Visual Studio .NET applications. Print Barcode In None Using Barcode encoder for Software Control to generate, create bar code image in Software applications. Circuit topology Device modeling Simulator setup The DC analysis may fail to converge because of incorrect initial voltage estimates, model discontinuities, unstable/bistable operation, or unrealistic circuit impedances. Transient analysis failures are usually due to model discontinuities or unrealistic circuit, source, or parasitic modeling. In general, you will have problems if the impedances, or impedance changes, do not remain reasonable. Convergence problems will result if the impedances in your circuit are too high or too low. The various solutions to convergence problems fall under one of two types. Some are simply band aids that merely attempt to x the symptom by adjusting the simulator options. Other solutions actually affect the true cause of the convergence problems. The following techniques can be used to solve a majority of convergence problems. When a convergence problem is encountered, you should start at solution 0 and proceed with the subsequent suggestions until convergence is achieved. The sequence of the suggestions is structured so that they can be incrementally added to the simulation. The sequence is also de ned so that the initial suggestions will be of the most bene t. Note that suggestions that involve simulation options may simply mask the underlying circuit instabilities. Invariably, you will nd that once the circuit is properly modeled, many of the options xes will no longer be required! General Discussion Many power electronics convergence problems can be solved with the .OPTIONS GMIN parameter. GMIN is the minimum conductance across all semiconductor junctions. The conductance is used to keep the matrix well conditioned. Its default value is 1E12 mhos. Setting GMIN to a value between 1n and 10n will often solve convergence problems. Setting GMIN to a value greater than 10n may cause convergence problems. GMIN stepping is an algorithm in PSpice and SPICE 3 that greatly improves DC convergence. This algorithm uses a constant minimal junction conductance that keeps the sparse matrix well conditioned and a separate variable conductance to ground at each node, which serves as a DC convergence aid. The variable conductances cause the solution to converge more quickly. They are then reduced, and the solution is recomputed. The solution is eventually found with a suf ciently small conductance. Then the conductance is removed entirely in order to DataMatrix Creator In None Using Barcode drawer for Software Control to generate, create Data Matrix ECC200 image in Software applications. Drawing GS1  13 In None Using Barcode printer for Software Control to generate, create European Article Number 13 image in Software applications. Code 39 Extended Creator In None Using Barcode generation for Software Control to generate, create Code39 image in Software applications. Encoding Barcode In None Using Barcode maker for Software Control to generate, create barcode image in Software applications. Paint EAN8 Supplement 2 AddOn In None Using Barcode generator for Software Control to generate, create EAN 8 image in Software applications. Make Universal Product Code Version A In Visual Studio .NET Using Barcode creator for VS .NET Control to generate, create Universal Product Code version A image in VS .NET applications. Bar Code Creator In Java Using Barcode generation for Android Control to generate, create barcode image in Android applications. Painting GS1  13 In Java Using Barcode generation for Java Control to generate, create EAN 13 image in Java applications. ECC200 Generation In C#.NET Using Barcode generator for .NET framework Control to generate, create DataMatrix image in .NET applications. Print UCC  12 In None Using Barcode creation for Online Control to generate, create GTIN  12 image in Online applications. Barcode Creator In Visual Studio .NET Using Barcode encoder for Reporting Service Control to generate, create bar code image in Reporting Service applications. Code 128A Maker In Java Using Barcode printer for Java Control to generate, create ANSI/AIM Code 128 image in Java applications. 
