Bilayer stator BLDC motor with auxiliary stator driven by one electronic speed controller for torque ripple and vibration reduction

Brushless DC (BLDC) motors driven by conventional six-step electronic speed controllers (ESCs) exhibit commutation torque ripple and vibration due to nonideal back-electromotive force and phase-current distortion. This article proposes a bilayer stator BLDC motor in which a mechanically phase-shifted auxiliary stator is introduced to generate a compensating torque component during commutation. Two drive configurations are investigated: a dual-ESC configuration with independent excitation of the main and auxiliary stators, and a single-ESC configuration in which phase-paired main and auxiliary windings are connected in parallel and driven by one three-phase inverter. The topology is evaluated using transient finite-element analysis, circuit-level interpretation, and hardware-based experimental validation. For the investigated six-slot/four-pole inrunner prototype, the proposed single-ESC configuration achieves an approximately 50% reduction in peak-to-peak electromagnetic torque ripple in simulation compared with a conventional BLDC motor under identical conditions. Experiments using the same fabricated motor reconfigured between conventional and proposed modes further show reduced no-load vibration at 500 and 1000 rpm under identical Hall-sensor-based six-step commutation conditions. Accordingly, the torque-ripple reduction claim is established primarily from simulation, while the experiments provide indirect hardware-based evidence consistent with the same mitigation mechanism. The results indicate that the proposed bilayer stator concept provides a practical structural approach to commutation torque-ripple mitigation, although the preferred drive configuration remains dependent on motor geometry, excitation strategy, and selected performance metric.