Design and Optimization of High-Efficiency Coreless PCB Stator Axial Flux PM Machines With Minimal Eddy and Circulating Current Losses

This paper proposes a systematic multi-step design procedure for highly efficient printed circuit board (PCB) stator coreless axial flux permanent magnet (AFPM) machines with minimal eddy and circulating current losses. The process begins with initial sizing, providing specific coefficients based on experience with multiple design projects. It continues with the optimization of the machine envelope design using an evolutionary algorithm and computationally efficient 3D finite element analysis (FEA) models. The subsequent step focuses on the detailed design of a PCB stator, aiming to minimize eddy and circulating current losses. Several open circuit loss mitigation techniques are proposed based on analytical equations and 3D FEA, while considering PCB manufacturing limitations and standards. The effectiveness of this design procedure is showcased through the design of an integral horsepower PCB stator coreless AFPM machine for HVAC applications, which was prototyped and tested. The experimental results indicated significantly reduced eddy current losses and virtually zero circulating currents, achieving 96% efficiency at a speed of 2,100 rpm and an output torque of 19 Nm. This outcome validates the efficacy of the proposed approach.