Control of Non-conventional Synchronous Motors

Chapter 5

Vectorial Modeling and Control of Multiphase Machines with Non-salient Poles Supplied by an Inverter ¹

5.1. Introduction and presentation of the electrical machines

This chapter is devoted to the modeling and control of electrical machines with at least two independent statoric currents. The star-coupled three-phase machine without a neutral terminal and the triangle-coupled three-phase machine are the most basic ones. More precisely, this chapter aims to emphasize the particularities created by a number of independent currents greater than two with respect to the classic three-phase machine.

To reach this goal, we will restrict ourselves to machines fulfilling certain hypotheses:

– constant magnetic air-gap (without variable reluctance effect);

– without magnetic saturation effect;

– built regularly, i.e. it is impossible to discriminate against phases as all of the phases are characterized by the same technological realization.

In practice, these hypotheses allow us to deal with at least two large families of machines:

– synchronous machines with surface-mounted magnets;

– squirrel-cage induction machines.

Obviously real machines do not perfectly fulfill the hypotheses, but we will assume that the phenomena induced by the non-fulfilling of these hypotheses generate second-order phenomena that can be implicitly compensated for by robust control.

For control, squirrel-cage induction machines can be distinguished from synchronous machines with magnets, mainly because ...