Performance Comparison of 15-Phase and 9-Phase Permanent Magnet Synchronous Generators Under Healthy, Fault, and Fault-Tolerant Control Conditions: A VSD-Based Analysis

Résumé fourni par la source

Multi-phase permanent magnet synchronous generators (PMSGs) are increasingly adopted in renewable energy systems and isolated microgrids due to their improved fault tolerance, reduced per-phase current stress, and enhanced power density compared to conventional three-phase machines. This article presents a systematic performance comparison between 15-phase and 9-phase PMSGs under four distinct operating conditions: healthy mode, single-phase open-circuit fault (Phase 1), and two fault-tolerant control (FTC) strategies. The first FTC technique involves opening a second phase with approximately 90-degree phase displacement from the faulty phase to attenuate power oscillations and reduce current amplitude imbalances. The second technique involves isolating a complete three-phase set containing the faulty phase without adapting the machine model. Both machines are modeled using the vector space decomposition (VSD) approach under field-oriented control (FOC), and simulations are performed in MATLAB/Simulink. Performance metrics include power efficiency, power losses, power ripple factor, electromagnetic power ripple, stator RMS current evolution, and stator current balance. Results demonstrate that the 15-phase PMSG consistently exhibits lower power ripple (6.5% vs. 15.54% under open-circuit fault), higher efficiency (89.02% vs. 87.44%), and reduced power losses across all fault scenarios. The first fault-tolerant strategy improves performance in both machines but is more effective in the 15-phase configuration. To validate the findings beyond offline simulation, hardware-in-the-loop (HIL) experiments are conducted on an OPAL-RT real-time platform, where the complete system—the PMSG and converter models together with the FOC and fault-tolerant control algorithms—is implemented within its FPGA framework. The HIL results for electromagnetic power and d–q axis stator currents show close agreement with the MATLAB/Simulink results across all operating conditions, confirming the FPGA implementability of the proposed control strategies under real-time constraints. These findings provide actionable insights for the design and control of high-phase-count generators in grid-connected and isolated power systems.

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