Finite element analysis of permanent magnet synchronous machines with fractional slot tooth coil windings

Abstract

The permanent magnet synchronous machine with an external rotor is the most important device for high performance electrical drive systems in particular for hybrid electric vehicles. The paper discusses finite element analyses of such a machine with concentrated tooth coils in terms of a comparison of both Y-and D-connected stator windings. As the evolved electromagnetic torque is one of the most important design parameter, various ratios of tooth width and slot pitch are analyzed with the two connections of the stator winding. On the other hand, the phase voltages are compared between both Y-and D-connected stator windings. With an intent of a position sensorless control of the machine, special attention is given to the differential inductances in dependence on the angular rotor position. Finally, the numerically obtained results are compared with measurement results obtained from a prototype machine. Finite-Elemente-Analysen von Permanentmagnet-Synchronmaschinen mit Bruchloch-Zahnspulenwicklungen.Permanentmagnet-Synchronmaschinen in Außenl€ auferbauart z€ ahlen zu den wichtigsten Antriebsmaschinen f€ ur hochdynamische elektrische Antriebssysteme wie insbesondere in Hybrid-Elektrofahrzeugen. Zwecks Vergleich von Stern-und Dreieckschaltung der Statorwicklung werden Finite-Elemente-Analysen einer solchen Maschine mit einer Statorwicklung aus konzentrierten Zahnspulen beschrieben. Im Hinblick auf das elektromagnetische Drehmoment als der wichtigste Entwurfsparameter werden Geometrievarianten bez€ uglich verschiedener Verh€ altnisse von Zahnbreite zur Nutteilung f€ ur beide Schaltungen der Statorwicklung untersucht. Als weitere Parameter f€ ur den Vergleich der beiden Schaltungsm€ oglichkeiten der Statorwicklung dienen Strangspannungen und differentielle Induktivit€ aten. Insbesondere die Abh€ angigkeit der Induktivit€ aten von der Rotorwinkellage ist f€ ur die Anwendbarkeit einer lagegeberlosen Regelung von großer Bedeutung. Abschließend werden die numerisch ermittelten Ergebnisse mit jenen aus Messungen an einer Prototypmaschine verglichen.

Design and Validation of a Synchronous Reluctance Motor With Single Tooth Windings

“…This variation needs to be considered in drive control schemes, especially in sensorless control schemes, requiring multidimensional lookup tables stored. These findings are similar to those previously reported where the influence of sub-harmonics in certain machine geometries was observed to cause temporal and spacial variation of the d-q-axis inductances in an IPM (interior permanent magnet) motor [23], where it has also been noted the inadequacy of d-q theory [24]. In the case of the synchronous reluctance motor, as the airgap length is small due to its inverse relation with the machine magnetizing inductance, power factor and torque capability, the localized effects caused by the higher order harmonics are increasingly pronounced on the d-q axis inductances…”

Influence of Travelling Current Linkage Harmonics on Inductance Variation, Torque Ripple and Sensorless Capability of Tooth-Coil Permanent-Magnet Synchronous Machines

“…It is observed that, because of the TC-windings, the saturation of TC-PMSMs is position-and time-dependent under the influence of current linkage sub-harmonics. In [17] it is reported that inductances of TC-PMSMs vary with the rotor position. This inductance variation is caused mainly by local saturation effects due to the asynchronous harmonic magnetic fluxes.…”

Electromagnetic-based evaluation of different Halbach array topologies with gap consideration for the permanent magnet synchronous machines

“…The paper also analyzes the way the modified 2-segmented halfback array develops its performance in comparison with the classic 2-segmented halfback array model for the outer rotor PMSM with a double-layer and 2nd-grade fractional slot winding [10,11]. All the significant EM perspectives are performed with the gap consideration among the FE models using a design function with a number of constraints.…”