Inverter fuzzy speed control of multi-machine system series-connected fed by a single five-phase an asymmetrical 19-level inverter with less number of switches

Introduction. 5-phase permanent magnet synchronous machines (PMSMs) are widely used in modern electric drive systems due to their superior torque density, improved fault tolerance, and reduced torque ripple. These characteristics make them ideal for demanding applications such as electric vehicles, aerospace systems, and industrial automation. Problem. Despite their advantages, conventional multi-machine systems using multilevel inverters and PI controllers suffer from sensitivity to parameter variations, high torque ripple, and increased cost and complexity due to the large number of power switches. The goal of this work is to design and validate a compact robust drive system that enables independent vector control of two series-connected 5-phase PMSMs using a reduced switch count asymmetrical 19-level inverter and fuzzy logic controllers. Methodology. The proposed system is modeled in the phase domain and transformed using Clarke and Park transformations to enable decoupled control. Mamdani-type fuzzy logic controllers are implemented for both speed and current regulation. The system is simulated in MATLAB/Simulink to evaluate performance under dynamic conditions and parameter variations. Results. The fuzzy logic controller significantly outperforms the conventional PI controller, achieving a settling time of 0.06 s versus 0.15 s, a steady-state speed error of 0.4 % compared to 1.9 %, and a torque ripple reduction of 47 %. Under robustness testing with doubled inertia, the fuzzy controller maintains stable and accurate control, whereas the PI controller fails. Additionally, the inverter achieves near-sinusoidal output with a total harmonic distortion of less than 4.5 %, and the switch count is reduced by 66 % compared to traditional 36-switch designs. Scientific novelty. This work presents the first implementation of independent vector control for two series-connected PMSMs using a single 12-switch asymmetrical 19-level inverter and model-free fuzzy logic control, offering a simpler and more efficient alternative to existing approaches. Practical value. The proposed system provides a highly efficient and cost-effective solution for electric drive applications where space, reliability, and control robustness are essential, such as in electric transportation, avionics, and compact industrial systems. References 26, tables 4, figures 9.