Design and Performance Enhancement of a PCB-Based Axial-Flux Stepper Motor

This paper presents a disc-type stepper motor based on PCB technology. Aiming to provide a solution for the difficulty of torque enhancement in multi-pole PCB stepper motors under the limited wiring space of the PCB stator, a novel spiral winding configuration is proposed. Without increasing the number of PCB stator layers or the overall dimensions, an axially offset layout is employed to enlarge the coil flux-linkage area, thereby increasing the electromagnetic torque. Theoretical analysis and finite element simulation results show that the proposed winding achieves approximately 30% higher torque than conventional spiral windings. Meanwhile, to address the current fluctuation problem caused by the low-inductance characteristic resulting from the coreless PCB stator, the influence of current ripple on the microstepping drive of the stepper motor is analyzed. A series-inductor approach is adopted to suppress current fluctuation, and the optimal inductor value is selected through theoretical calculation and simulation, which effectively reduces the current ripple and significantly improves the microstepping performance. Finally, a prototype is fabricated and tested experimentally. The results indicate that the motor output torque reaches 46.4 mN·m, and the step-angle error under 16-microstep drive is within 0.25°, providing a feasible solution for the design and control of PCB stepper motors in compact spaces.