An Adaptive FOC-DTC Hybrid Strategy with a Fuzzy Decision-Making Unit and an RLS-Based Harmonic Compensator for Torque Ripple Minimization in a Nine-Phase Permanent Magnet Synchronous Motor

Nine-phase permanent magnet synchronous motors (PMSMs), by virtue of their inherent reduction in torque harmonics and fault-tolerant capability, are an ideal choice for sensitive industrial applications. However, selecting between the two prevalent strategies, field-oriented control (FOC) and direct torque control based on space vector modulation (DTC-SVM), has consistently involved an intrinsic trade-off: FOC provides low torque ripple and high-quality sinusoidal currents but exhibits a limited dynamic response, whereas DTC-SVM delivers an ultra-fast response yet generates higher torque ripple and harmonic distortion. This paper proposes an adaptive hybrid control architecture for a ۱۰ kW nine-phase surface-mounted permanent magnet synchronous motor (SPM) that resolves this trade-off by simultaneously harnessing the advantages of both methods. The core of this architecture is a fuzzy decision-making unit that determines the active control mode between FOC and DTC-SVM continuously and bumplessly by analyzing the speed error and its rate of change in real time. In the FOC mode, an adaptive compensator based on the recursive least squares (RLS) algorithm identifies the amplitude and phase of the sixth- and twelfth-order torque harmonics and eliminates them via q-axis current injection. In the DTC-SVM mode, a fuzzy regulator adjusts the gains of the torque PI controller online. A bumpless transfer mechanism is also incorporated to eliminate transient disturbances at the instant of mode switching. Simulation results under various load profiles (up to ۱۲۰% of the rated load) indicate that the proposed method achieves a ۹۰% reduction in torque ripple relative to standard FOC and ۹۱.۷% relative to DTC-SVM, while concurrently improving the speed dip against a load step by ۶۵% and maintaining the recovery time at the DTC-SVM level. This performance renders the adaptive hybrid approach an ideal solution for multiphase drives with dual performance requirements.

کلیدواژه ها:

Nine-phase permanent magnet synchronous motor ، FOC-DTC hybrid control ، fuzzy decision-making unit ، adaptive harmonic compensator ، recursive least squares (RLS) ، torque ripple