Comparisons of Concentrated Printed-Circuit Stator Windings for Axial Flux Permanent Magnet Machines

Printed-circuit stator windings allow low-profile construction, zero cogging torque, and high power density when used for axial flux permanent magnet machines. Trapezoidal and rhomboidal windings are the two most popular printing patterns. Since the printedcircuit board (PCB) area is limited and the separation between the conductor traces is inevitable due to manufacturing requirements, it is critical to assess the winding patterns in terms of the torque producing capability and the area utilization. In this paper, we present a detailed analysis of winding patterns and determine the torque produced by the winding patterns. It is found that the trapezoidal pattern produces much larger torque, but the rhomboidal pattern has smaller copper losses. In terms of the torque normalized by the coil resistance, the trapezoidal pattern is 12% better than the rhomboidal pattern of the same geometry.