Reduction of higher harmonic sequences in terminal voltage of an AC exciting synchronous generator using magnetically anisotropic slot wedges

Abstract

This paper describes relationships between characteristics of a magnetically anisotropic slot wedge and voltage higher harmonics in an ac exciting synchronous generator terminal due to permeance ripple caused by an open‐slot‐type rotor. From the relationships obtained, practical guidelines were formulated for machine designs applying the magnetically anisotropic slot wedge. The results are as follows. (1) Equivalent permeability of the magnetically anisotropic slot wedge became isotropic wedge permeability for air‐gap flux ripple. (2) Two ways were identified to reduce voltage‐higher harmonics by using the slot wedges. (3) The level of leakage flux passing through the anisotropic slot wedge was determined only by its permeability in the width direction. (4) Effectiveness of the magnetic anisotropic slot wedges inserted into the stator slots was verified from experimental results using a model machine of the open‐ slot‐type rotor.