The saturation of leakage reactances in electrical machines

The usually accepted hypothesis of constant leakage reactances in electrical machines must be reviewed. This correction is suggested by two experimental results: while the leakage reactance of a transformer is practically constant, for a synchronous machine, the leakage reactance practically saturates as the main magnetic circuit. The air-gap of rotating machines plays an important role to bound the leakage fluxes; namely, there is a part of the leakage fluxes concerned by the main magnetic circuit. To take into account this fact, we postulate a saturated model of leakage reactances, where, the leakage reactance is'composed by two parts: one is constant and the other is dependent upon the machine saturation level. Some experimental results obtained with a three-phase wound-rotor induction machine confirm the assumption.