Selection of Flux Level in Field-Oriented Induction Machine Controllers with Consideration of Magnetic Saturation Effects

The magnitude of rotor flux is a primary design and application variable for field-oriented induction machine controllers. Optimization of a nonsaturating machine controller for peak torque/A will lead to operation at the peak of the constant current torque-versus-slip curve. It is shown how flux level selection for both standard and high efficiency motors is altered by including saturation characteristics. Theoretical and experimental approaches for calculation of flux-producing current in the presence of magnetic saturation are presented. The theoretical method includes a straightforward two-parameter saturation model, which is demonstrated to possess characteristics very close to experimental data. This approach contributes substantial insight to saturated machine analysis while retaining relative simplicity as a design tool. The experimental approaches developed are straightforward and general.