2. Modeling saturated rotating field synchronous machines

Saturation of the magnetic circuit adds a significant degree of complexity that simple equivalent diagrams cannot, strictly speaking, handle, since the notion of inductance defined in linear operation is no longer valid, and fluxes no longer add up. However, based on certain approximations, we can adopt a simple approximation model, giving a good approximation of the machine's performance in the case of moderately saturated operation.

The assumptions or approximations classically adopted are as follows:

• waveforms (magnetomotive forces, air-gap induction, flux, EMF, etc.) remain sinusoidal and can be decomposed along both direct and transverse axes. Saturation only affects the rms values of magnetic and electrical quantities. This means that we can continue to use the Fresnel vector representation and complex calculus;...