Fault-tolerant Axial Flux Coreless PM Machines with Independent Phase Modules

In this paper, a fault-tolerant two-phase high power coreless axial flux PM (AFPM) machine with a modular structure is introduced. The performance of this machine, in terms of torque, power density, and efficiency, is compared with its three-phase counterpart configuration based on finite element analysis (FEA) and experimental results. The fault tolerance of these two configurations, considering the control systems, is also compared. A detailed power loss breakdown for the prototype two-phase and three-phase printed circuit board (PCB) stator coreless AFPM machines derived from experiments is presented, showcasing that the introduced fault-tolerant two-phase machine has comparable performance and efficiency, while the phase windings are electrically insulated and magnetically decoupled. The common configurations for controlling a two-phase machine, namely four-leg and three-leg two-phase inverters, are also discussed along with the experimental results.