Conclusion
Variable reluctance machines (VRM) - MRV principles. Switching machines

The physical principles of variable reluctance are very simple and immediately applicable to the modeling and design of single-phase actuators.

As for multiphase "commutated" machines, which make up the vast majority of industrial applications, they have practically magnetically independent phases that constitute single-phase devices: here again, modeling is easy, and design is complicated only by the need to combine the geometry of "pads" and teeth, and to optimize waveforms and power supply sequences.