Design of a miniature axial-flux spindle motor with rhomboidal PCB winding

Size reduction has become one of the most important aspects of motor design. This paper presents a miniature axial-flux spindle motor with a rhomboidal printed circuit board (PCB) winding. The design of its mechanical structure aims to eliminate any unnecessary space. Prior to prototyping, the motor geometry is calculated using an approximate analytical model, which helps speed up the design process. The flexible PCB winding represents an ultrathin electromagnetic exciting source where coils are wound in a rhomboidal shape in order to reduce the end-winding length and minimize the copper loss. The design process also incorporates finite-element analysis for further performance evaluation and refinement. The proposed motor is prototyped, and excellent agreement is found between simulation and measurement.