Inductance Calculation of Tooth-Coil Permanent-Magnet Synchronous Machines

Abstract

Abstract-Analytical calculation methods for all the major components of the synchronous inductance of tooth-coil permanentmagnet synchronous machines are reevaluated in this paper. The inductance estimation is different in the tooth-coil machine compared with the one in the traditional rotating field winding machine. The accuracy of the analytical torque calculation highly depends on the estimated synchronous inductance. Despite powerful finite element method (FEM) tools, an accurate and fast analytical method is required at an early design stage to find an initial machine design structure with the desired performance. The results of the analytical inductance calculation are verified and assessed in terms of accuracy with the FEM simulation results and with the prototype measurement results.Index Terms-Fractional slot winding, inductance calculation, leakage inductance, permanent-magnet synchronous machine (PMSM), tooth coil.

On the Influence of Increased Stator Leakage Inductance in Single-Tooth Wound Synchronous Reluctance Motors

“…In a conventionally wound machine with integer slot distributed windings, the air gap harmonic leakage factor is of the magnitude of <0.08 [17,20] when ≥ 2, compared to the chosen fractional slot concentrated winding of 0.462, which is in agreement with [21,22]. This is a cause for concern, but does provide an explanation to why the power factor is inherently low in the cSynRM motor topology and also illustrates why the stator leakage inductance should be considered a design parameter for the single tooth wound synchronous reluctance motor.…”

“…The procedure follows that in standard text book approach given by Pyhronen [17] and Gieras [20], as well being employed in [21] for PM machines -the full equations are not repeated here and the reader is referred to the references. The purpose of the present and following sections is to identify the dominant stator leakage component in the design, firstly the construction leakage inductance is examined and then the increased MMF harmonic contribution to the stator leakage inductance.…”

Analytical Calculation of D- and Q-axis Inductance for Interior Permanent Magnet Motors Based on Winding Function Theory

“…L 0 consists of end-winding leakage inductance, slot leakage inductance and tooth-tip leakage inductance. The detailed computation processes of the leakage inductance are expressed in [24]. The end-winding leakage inductance can be calculated by…”

“…where λ w is the slot leakage permeance factor, which is relative to slot dimensions [13,24]. The tooth-tip leakage inductance is…”

“…where λ tt is the tooth-tip leakage permeance factor, and k tt is a factor that takes into account the presence of different phases in a slot [24]. The armature reaction airgap magnetic fields in the q-axis can be obtained by …”