Simscape Electrical Solver configuration

Hi

I am using Simulink simscape electrical. Initially I verified my simulink electrical simulation circuit against my LT spice model of the switching regulator (buckboost) for a variety of use cases. Recently I have been getting some unexpected results in Simulink, e.g. the output voltage doesnt reach the desired setpoint regardless of dutycycle. So I went back to LT Spice to check and it seems there is a discrepancy.

I have the following solver setup windows to play with:

1. Model Settings > Solver
2. Block Parameters > Solver Configuration

I have played around with most of the parameters to see what changes occur but it's mostly at random, including:

• Alternating between fixed and variable step
• Using Backward Euler and Trapezoidal Rule solvers
• Turning zero crossing detection on & off
• Reducing sampling time to the minimum possible without introducing aliasing from my switching converter

None of this makes my output resemble my LT Spice model. How can I set up my solver to make it produce results consistent with LT Spice?

In Solver Configuration we have the option of using a local solver or unchecking this box? Does this mean we can feed in some external solver, .e.g. LT SPice or other spice software somehow?

Answer 1

[Bruno Rodriguez Esteban]

Hi Sea,

It is a bit difficult to guess without any reproduction model. It could be something different to the solver what is causing the discrepancy. In case you haven't used them, there are various SPICE-compatible semiconductors:https://www.mathworks.com/help/releases/R2020b/physmod/sps/spice-semiconductors.html

Regarding the solver, if you uncheck the box, you would be using Simulink's solver: https://www.mathworks.com/help/releases/R2020b/simulink/ug/choose-a-solver.html

If you check it, you will be using a specific fixed-time solver for Simscape: https://www.mathworks.com/help/releases/R2020b/physmod/simscape/ref/solverconfiguration.html

Hope it helps,

Bruno