2. Excited reluctance machines

The pure reluctance machines studied above all have a mediocre power factor. Excitation can improve this parameter, at the cost of installing a DC power supply and additional coils, or more often permanent magnets. Excited machines also have a linear torque-current characteristic (at least at low current values), which is an advantage in some applications.

It should be noted that the pseudo-serial excitation of single-phase machines (cf. ) gives torque performance identical to pure AC power, with identical winding constraints (same peak value and same RMS current value). This pseudo-excitation is feasible in multiphase machines, either implicitly by means of square-wave currents, or with an AC supply and a diode circuit (self-excitation