Practical considerations on the off-line measurements ofPMSM and SyRM inductances

The synchronous inductances of permanent magnet machines are usually measured by means of off-line measurements based on single-phase connection schemes of the three-phase windings. Through experiments and comparative analyses with respect to the three-phase symmetrical supply case, it has been observed that the results obtained for the inductance measurement is dependent on both the winding connection scheme applied and the rotor position. As a result, a new perspective is provided on the generally adopted methodology for off-line measurements of synchronous inductance. In particular, this paper highlights the relationships between the connection schemes' influence on the inductance values, using several surface mounted PMSM and synchronous reluctance machines. The study also covers machines equipped with distributed windings as well as those with fractional slot concentrated windings.