Simulation slowed down by universal bridge diode rectifier

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Andrea Medolago 2024-5-17

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https://ww2.mathworks.cn/matlabcentral/answers/2119876-simulation-slowed-down-by-universal-bridge-diode-rectifier

回答： Joel Van Sickel 2024-5-28

I'm doing a simulation in Matlab Simulink using Simscape Electrical Specialized power systems. The aim of my simulation is to model a synchronous machine with brushless excitation. The brushless excitation requires a rotating rectifier bridge, modelized in my simulation using the block "universal bridge". The addition of this block considerably slows down my simulation (i need 3 of them in my system), to the point that 5s of simulation can take hours.

I also created my block of the diode bridge rectifier using diodes from specialized power systems but i have the same problem.

The solver I'm using is ode23tb with a max step size 1e-3, relative tolerance 1e-3 ( in order to have correct waveforms I should use at least 1e-4, 1e-4 but it would make the simulation slower). I already tried accelerator and rapid accelerator without any improvements.

Does anyone have any syuggestion on how to resolve this simulation speed problem?

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Andrea Medolago 2024-5-21

Follow-up : I've noticed via the solver profile that my model coupled with a diode bridge rectifier present many solver exception, I think this is the cause of the lack of simulation speed. Since this model needs to be coupled with a diode bridge and will be inserted in a bigger scheme, it needs a good simulation speed to not compromise the whole simulation. I've already tried all the tricks i found online, I always have a problem with the integrators in my continous ode equations.

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Answer 1

Joel Van Sickel 2024-5-28

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Can you share your model? One issue is that the diode rectifier IS supposed to slow your simulaiton down. It is adding switching level events to your model that require the solver to do a reset every time a diode switches from blocking ot conducting. This will basically add 6x motor electrical frequency solver resets to a model that beforehand might not have had any. Now, given that, there still might be ways to improve the performance. Are you running the motor at nominal power or also at low powers? Specialized power systems is not very good for modelling motors at low power, and simscape would be a better technology for that type of analysis. You could try switching to a fixed step solution on the powergui. If your solver is hanging, this will speed things up, but mostly just tells you something was wrong with the model but you can skip fixing it if the fixed step solution works. Otherwise, adding snubber resistances and tweaking existing snummber resistances and solver settings might help, but that's hard to say unless you post your model here for review.