E. Schmidt, M. Susic, A. Eilenberger:
"Design Studies on an External Rotor Permanent Magnet Synchronous Machine for a Position Sensorless Control - Comparison of Star- and Delta-Connected Stator Winding";
Talk: IEEE Conference on Electromagnetic Field Computation (CEFC), Chicago IL, USA; 05-09-2010 - 05-12-2010; in: "Proceedings of the 14th IEEE Conference on Electromagnetic Field Computation (CEFC)", (2010), ISBN: 978-1-4244-7061-7; 1 - 4.

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 presents finite element analyses of a such a machine in terms of a comparison of both star- and delta-connected stator windings. Thereby, the unknown zero sequence current with the delta-connected stator winding has to be determined iteratively for each angular rotor position with all operating conditions.
The most important design parameters such as electromagnetic torque, phase voltages are compared against both connections of the stator winding.

http://publik.tuwien.ac.at/files/PubDat_192562.pdf