SIMULINK BASICS For Particular Applications

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

Answer 1

[Grégory SEABRA]

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

Answer 2

[Karan123]

Hello Grégory SEABRA,

Many of Thanks from my Side for your precious time.

1) Can you help me of Simulate Attached Model. Why It is quite Slow [Unable To See results after 15 Hours. With Simulation Stop Time 1.0] ?

2) To ON-OFF IGBT , Also the In Pulse Generator Set Amplitude 15V . After "Not" Gate When I have trying to reverse 15V Reduces 1V. Why So ?

3) Is it good way to chose Transformer MultiWinding Transformar . Actually I want to use 7:1 Single Phase Transformer. As per configuration I have not seen anything in Voltage SCOPE .

My System Configuration is as below:

Processor: Intel® Core i5 CPU M480 @2.67 GHz

RAM : 4.00 GB

System Type: 64-Bit Operating System

Matlab R2010a (7.10.0.)

The Main thing is how to speed up this. Why It is so Slow?

Also I am Seen another Demo with Discrete Ts = 5.144e-006s for Single Phase PWM Inverter With FixedStepDiscrete

But It uses IGBT as per below Paramaters:

Internal Resistance,Subber Resistance , Snubber Capacitance.

But I have using IGBT as per below Paramaters:

Internal Resistance, Inductance Lon, Forward Voltage, Current 10% Fall Time Tf Current 10% Tail Time Tt Initial Current Ic Subber Resistance , Snubber Capacitance.

What is the error in my Design ?

-- KR

[Grégory SEABRA]

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.