Active Harmonic Suppression of Low-Reactance Multiphase Slotless Permanent Magnet Synchronous Machines

Harmonic suppression plays a key role in the current control of dual-three-phase (DTP) permanent magnet synchronous machines (PMSMs). Existing current control schemes are scarcely verified by designed DTP motor prototypes or consider the impact of inherent electromotive force (EMF) harmonics quantitatively. Also, few studies discuss the low-reactance case, which requires additional concerns for current prediction and modulation. Therefore, this article conceives and presents an improved deadbeat-based active current harmonic control scheme particularly for low-reactance PMSMs. From the aspect of motor design and finite-element analysis, the quantitative effect of EMF harmonics on control behaviors is analyzed. Based on the nonideal mathematical model (MMM) of the designed slotless PMSM with analyzed EMF harmonics, the proposed scheme is first introduced theoretically and verified by simulation. Subsequently, the slotless PMSM prototype fabrication and control experiments validate the proposed scheme and recognize the necessity of active harmonic suppression.