A New Winding Design Method for High Pole Number, Bearingless Machines

In this paper a general method has been determined for selecting the slot-pole combination for high pole, bearingless motors, using combined windings. The method can be applied to a range of pole numbers to derive a suitable winding configuration with a high winding factor, delivering a smooth force and torque. A unique switching function is implemented to modulate the winding excitation between force and torque generation, which in turn allows the definition of acceptable combined winding arrangements for use with a dual inverter arrangement. The principles and method are presented, followed by FEM analysis on a double layer, slotless motor design.