How to replicate the SPS MMC "Aggregate Model" behavior in the Simscape Electrical MMC arm block?

I am currently migrating my HVDC simulation models from Simscape Electrical: Specialized Power Systems (SPS) to the Simscape Electrical (Fundamental) library.

In the SPS library, the Modular Multilevel Converter (MMC) block offers a specific "Model fidelity" option called "Aggregate model". However, in the fundamental Simscape Half-Bridge MMC arm block, I do not see an explicit "Aggregate" option.

1. Does the "Equivalent model - PWM-controlled" in Simscape correspond to the SPS "Aggregate model"?
2. If so, what is the standard way to configure the gate inputs to achieve the "Aggregate" behavior (perfectly balanced capacitors)? Should I simply feed the same duty cycle to all submodules via a vector expansion (e.g., using repmat) to bypass the sorting algorithm?
3. Is there a different recommended workflow in Simscape Fundamental for simulating 200+ SMs per arm without running a detailed switching model?

Any advice on the best practice for this transition would be appreciated.

Answer 1

[Sabin]

In Simscape Electrical, the Modular Multilevel Converter Arm provides two options for aggregating the submodules by setting the Fidelity level to either:

- Equivalent Model – PWM-controlled

- Equivalent Model – waveform-controlled

When using Equivalent Model – PWM-controlled we need to provide PWM signals for all submodules. When using Equivalent Model – waveform-controlled we need to provide the modulation waveforms.

Since R2025a, there is an in-product example showing how to use these two modes:

https://www.mathworks.com/help/sps/ug/high-voltage-direct-current-transmission-with-modular-multilevel-converters.html