Round conductive bars embedded in semi-closed slots are frequently used in the construction of electric machinery, for instance in the squirrel cage of induction motors. Frequently, such as in the study of induction motor steady-state performance at rated slip, it is useful to estimate the slot leakage inductance of these conductors under the hypothesis of no eddy currents and no magnetic saturation. This is usually done through simple approximated analytical formulas available in the literature. In this paper, an improved explicit ready-to-use leakage inductance expression for circular bars embedded in semi-closed slots is derived by solving Poisson's equation in the slot domain. The precision of the proposed formulation is assessed against Finite Element Analysis (FEA) for various slot geometries and is shown to always give very accurate results, with errors below 2%. Conversely, approximated simplified formulas available from the literature are demonstrated to possibly give large errors, which exceed 20% for some explored slot geometries.

An improved analytical expression for computing the leakage inductance of a circular bar in a semi-closed slot / Bortolozzi, M.; Branz, L.; Tessarolo, A.; Bruzzese, C.. - (2015), pp. 1-5. (Intervento presentato al convegno International Conference on Sustainable Mobility Applications, Renewables and Technology, SMART 2015 tenutosi a Kuwait) [10.1109/SMART.2015.7399265].

An improved analytical expression for computing the leakage inductance of a circular bar in a semi-closed slot

Bortolozzi M.;Bruzzese C.
2015

Abstract

Round conductive bars embedded in semi-closed slots are frequently used in the construction of electric machinery, for instance in the squirrel cage of induction motors. Frequently, such as in the study of induction motor steady-state performance at rated slip, it is useful to estimate the slot leakage inductance of these conductors under the hypothesis of no eddy currents and no magnetic saturation. This is usually done through simple approximated analytical formulas available in the literature. In this paper, an improved explicit ready-to-use leakage inductance expression for circular bars embedded in semi-closed slots is derived by solving Poisson's equation in the slot domain. The precision of the proposed formulation is assessed against Finite Element Analysis (FEA) for various slot geometries and is shown to always give very accurate results, with errors below 2%. Conversely, approximated simplified formulas available from the literature are demonstrated to possibly give large errors, which exceed 20% for some explored slot geometries.
2015
International Conference on Sustainable Mobility Applications, Renewables and Technology, SMART 2015
analytical methods; Poisson's equation; rotor leakage inductance; semi-closed slots; squirrel cage induction motors
04 Pubblicazione in atti di convegno::04b Atto di convegno in volume
An improved analytical expression for computing the leakage inductance of a circular bar in a semi-closed slot / Bortolozzi, M.; Branz, L.; Tessarolo, A.; Bruzzese, C.. - (2015), pp. 1-5. (Intervento presentato al convegno International Conference on Sustainable Mobility Applications, Renewables and Technology, SMART 2015 tenutosi a Kuwait) [10.1109/SMART.2015.7399265].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1308943
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