Direct and quadrature inductances measurement of the permanent magnetic linear synchronous machines

Permanent magnetic linear synchronous machines (PMLSMs) are playing a more important role either in transportation systems or magnetic launch systems, for the excellent advantages. It is indispensable to high performance controllers that some machine parameters are known such as the direct axis (d-axis) and quadrature axis (q-axis) inductances. In this paper, self and mutual inductances of the three-phase winding are deduced by basic electric machinery theory, and the measured inductances are analyzed since the mutual inductances and the corresponding terminals among three-phase windings are changing as different phase winding is concerned. The d- and q-axis inductances are measured with the designed circuit, and the experimental measurement method is validated by the comparison between the experimental and finite element method (FEM) results.

Research highlights
► The d- and q-axis inductances are derived theoretically.
► The new measurement principle of the d- and q-axis inductances is analyzed.
► A corresponding measuring circuit is developed.
► Measurement results match those of the FEM well.