you've already found the interface blocks that allow you to connect the two electrical simulation technologies. While this can work, in general, the ideal solver for one technology is not the ideal solver for the other. For this reason, we recommend picking one technology, and modelling your full system with that to get better simulation performance and more accurate results. The Interfaces add some delay/filtering which can impace simulation results if not used correctly. For and inverter and BLDC control, both technologies offer equivalent models that would work well. If you provide some specifics about the main goals of your model, I might be able to recommend one over the other. To help with terminology, the black outline blocks are called specizlied power systems, while the blue blocks are simscape. It's confusing since both are inside the simscape electrical toolbox, but the specizlied power systems blocks actually use simulink underneath the hood, which is why they do not need a solver configuraiton.