Coil Winding Circuit Configurations for Permanent Magnet Synchronous Machines

Abstract

The article outlines a procedure for drawing up the electric circuits of coil-type armature windings for salient-pole PM electric machines proceeding from the required number of pole pairs (the synchronous rotation frequency) and the number of phases. The procedure implementation algorithm is based on determining the stator teeth number as the one nearest to the number of rotor poles (2p) multiple to the number of phases. In this way, sufficient levels of coil pitch coefficient and winding coefficient are ensured. In accordance with the developed procedure, the coils in the phases can occupy one, two, or four phase zones from the adjacent coils connected into coil groups in a series opposition manner. The algorithm was tested on a few examples of drawing up the connection circuits of synchronous machine windings known from the electrical machinery construction theory and practice, including serially produced ones with the inner stator and for a pilot design of a high-capacity motor. For the latter one, its versions with three- and nine-phase windings for a 32-pole rotor (2p = 32) are compared. Numerical studies of the motor torque for both winding circuit versions carried out using the finite element method have shown that the version with the nine-phase winding produces a 20% higher torque. For one version of a serially produced motor, the winding electric circuit design validity was checked by calculating the torque-angle curves for different current densities. In all examples, formal compliance with the items of the outlined procedure has yielded correct circuit solutions. A criterion for evaluating the PM machine manufacturing complexity has been proposed, which depends on the winding type (distributed or coil-type) and on the number of PMs per magnetic system pole.