A periodic adaptive controller for the torque loop of variable speed brushless DC motor drives with non-ideal back-electromotive force

In this paper, an adaptive current controller is proposed for variable speed brushless direct (BLDC) motor drives to minimize the output torque ripples caused by parametric and periodically varying uncertainties. Phase-to-phase non-ideal back-electromotive force (back-EMF) in BLDC changes with respect shaft angle, hence period of these signals alters depending on rotor frequency. To address problems, uncertain dynamics reformulated transforming time variable, then periodic employing instantaneous estimation values unknown signal developed achieve ripple reduction. The back-EMF waveform achieved considering switching between conduction commutation periods. Also, update rules based adaptation uncertainties are derived, thus, hybrid differential-periodic obtained phenomenon. Asymptotic convergence phase currents reference proven appropriate Lyapunov–Krasovskii function angular position. Comprehensive numerical simulation studies have been successfully carried out verify performance effectiveness applications.