SIMULINK BASICS For Particular Applications
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Karan123
il 14 Nov 2016
Commentato: Grégory SEABRA
il 15 Nov 2016
Hello Sir,
I want to know on below things about MATLAB Simulink.
1)How to Select Resolver in Simulink ? for Particular Applications. Like ode23tb , ode45 or FixedPoint Resolver VariablePoint Resolve what ? for particular application
2)What is the difference between Powergui Continuous or Discrete ? How to Select it for particular application.
3) How to chose Simulation Stop Time ? for different Circuit
I have to work on IGBT with ON , OFF State Feature from MATLAB and Transformer etc .
My Design show No Errors. But Unable to see output waveform after 16 Hours of Simulation.
-- KR
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Grégory SEABRA
il 14 Nov 2016
Hi,
ode45 is simulink default solver, a medium-order, whereas ode23 is a low-order solver.
These are variable-step solvers, which will adapt their step-time regarding the dynamics of the equations outputs.
Depending on the accuracy and the type of differential equations you have to solve, you will choose between different solvers with different integration methods. https://fr.mathworks.com/help/matlab/ref/ode23.html
Fixed-step solvers can be used to accelerate you simulations, but be aware that the accuracy will be impacted depending on how you choose your step-time. Furthermore, you might get numerical oscillations when simulating systems with high dynamics (e.g SPS transformers with saturable cores). If you have a full discrete model (fixed sample time), you can use a discrete solver with the time-step equal to your design's minimum sample time.
- PowerGUI is SimPowerSystems solver. You need it to run simulations while using SPS elements. When using the continuous one, the solver step will vary along the simulation, resulting in long simulations. When choosing a discrete solver, you'll specify the time-step regarding your system's dynamics.
For example, if you have IGBTs switching @16kHz, you would then want to have between 50 to 100 steps between switching events, resulting in a time-step of approximately 1µs.
But keep in mind that it is all about making a trade-off between accuracy and simulation speed.
Finally, you will choose your simulation stop time regarding the purpose of your simulations and your system's dynamics. You might want to know if you want to observe steady-states or transients, or run a complete scenario.
For your application with SPS & transformers, I'd recommend using ode23t with a continuous or maybe a discrete PowerGUI if needed.
Regards,
Greg
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Karan123
il 15 Nov 2016
Modificato: Karan123
il 15 Nov 2016
1 Commento
Grégory SEABRA
il 15 Nov 2016
Hi,
I'm sorry but I am currently waiting for my licence, so I'm unable to simulate and help you on this particular case at this moment.
Have you tried using ode23t & discretizing your PowerGUI?
Do you really need to simulate 1s? What's your switching frequency and what do you want to observe in this simulation? Switching transient? Steady state?
If you don't care about the switching transients and want to observe signals with a slower dynamics than your switching frequency, you could use an average model where there are no IGBTs but just Voltage sources driven by a signal resulting from the multiplication of the IGBTs duty cycles and the DC voltage.
It all depends on your simulations purpose.
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