TY - JOUR

T1 - Modeling of airgap flux density for the study of stator core vibration in low speed synchronous machines

AU - De Barros, Allan

AU - Chabu, Ivan

N1 - Publisher Copyright: © 2020, Emerald Publishing Limited.

PY - 2020/6/4

Y1 - 2020/6/4

N2 - Purpose: This paper aims to develop models and simulations focused on the prediction of electromagnetic forces acting on the stator core of a synchronous machine. It contributes to the study of stator core vibrations. Design/methodology/approach: An analytical model based on the rotating fields’ theory including the damper winding contribution was developed. Such model allows the comprehension of airgap magnetic field distribution and the consequent pressure distribution. Focus was given to the pressure sub-harmonics due to the usual fractional winding configuration of low speed machines. A comparative numerical model was also developed and applied to an example laboratory machine. Partial validation measurements were performed. Findings: The paper provides the predicted electromagnetic forces and the relative influences of damper winding and teeth tangential forces on each pressure harmonic. It is shown by how much such effects can influence the amplitude of pressure sub-harmonics from a fractional stator winding. Research limitations/implications: The performed validation measurements were based on the airgap field distribution, but the resulting core vibration at load was not measured. Therefore, researchers are encouraged to perform additional tests for improved validation. Practical implications: The obtained models and results are of great importance for the design phase of new generators and for the diagnosis process of existing machines with core vibration problems. Originality/value: As a contribution of this paper, the magnitude of indirect effect of tangential forces and the effect of damper winding are comparatively quantified for each pressure harmonic. The given approach contributes to the relative evaluation of these effects especially on the sub-harmonics from the fractional stator winding.

AB - Purpose: This paper aims to develop models and simulations focused on the prediction of electromagnetic forces acting on the stator core of a synchronous machine. It contributes to the study of stator core vibrations. Design/methodology/approach: An analytical model based on the rotating fields’ theory including the damper winding contribution was developed. Such model allows the comprehension of airgap magnetic field distribution and the consequent pressure distribution. Focus was given to the pressure sub-harmonics due to the usual fractional winding configuration of low speed machines. A comparative numerical model was also developed and applied to an example laboratory machine. Partial validation measurements were performed. Findings: The paper provides the predicted electromagnetic forces and the relative influences of damper winding and teeth tangential forces on each pressure harmonic. It is shown by how much such effects can influence the amplitude of pressure sub-harmonics from a fractional stator winding. Research limitations/implications: The performed validation measurements were based on the airgap field distribution, but the resulting core vibration at load was not measured. Therefore, researchers are encouraged to perform additional tests for improved validation. Practical implications: The obtained models and results are of great importance for the design phase of new generators and for the diagnosis process of existing machines with core vibration problems. Originality/value: As a contribution of this paper, the magnitude of indirect effect of tangential forces and the effect of damper winding are comparatively quantified for each pressure harmonic. The given approach contributes to the relative evaluation of these effects especially on the sub-harmonics from the fractional stator winding.

KW - Electrical machine

KW - Electromagnetic fields

KW - Force calculation

KW - Magnetic force

UR - http://www.scopus.com/inward/record.url?scp=85085871766&partnerID=8YFLogxK

U2 - 10.1108/COMPEL-01-2020-0012

DO - 10.1108/COMPEL-01-2020-0012

M3 - Article

AN - SCOPUS:85085871766

VL - 39

SP - 839

EP - 852

JO - COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

JF - COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

SN - 0332-1649

IS - 4

ER -