This article presents a multi-disc coreless axial flux permanent magnet synchronous machine (MDC-AFPMSM) with N pole and S pole type series magnetic circuit and open-end winding for high reliability applications, such as small power actuator system. Firstly, the topology and driving modes of MDC-AFPMSM are presented in details. In this article, a multi-objective optimization function is proposed to design the machine with full consideration of various influence factors. The drive performance indexes of four-phase, five-phase and six-phase machines are analyzed and discussed. Furthermore, main parameters of the five-phase MDC-AFPMSM with open-end winding are calculated. In order to reduce the torque ripple, the air gap magnetic flux is optimized. Finally, the operation characteristics under short-circuit and open-circuit faults are fully analyzed based on the three-dimensional (3D) finite element algorithm. Comprehensive simulation results and theoretical analysis have demonstrated that the open-end winding MDC-AFPMSM has much stronger fault-tolerant ability in comparison to that of conventional machines.