E-Core and C-Core Switched Flux Permanent Magnet Generators for Wind Power Generation

This paper introduces a 6-phase switched flux permanent magnet (SFPM) generator with high permanent magnet (PM) utilization, designed for a 2 kW wind power generation application. Two different SFPM generator variants were designed and analyzed by applying E-core and C-core techniques to a state-of-the-art (SOTA) benchmark SFPM machine structure. Key design variables, namely, the rotor pole number, split ratio, rotor pole width, and the number of turns per coil were optimized. The electromagnetic performance, specifically as a wind generator considering objectives of achieving high PM utilization, minimizing voltage waveform distortion, and reducing cogging torque, was evaluated using finite element analysis. The results obtained from the analysis demonstrated that both the E-core and C-core SFPM generators exhibited significantly higher flux-linkage per unit PM volume compared to the SOTA benchmark generator. In particular, the optimized C-core SFPM generator demonstrated nearly double the magnet utilization, half the cogging torque, and higher efficiency when compared to the benchmark SFPM generator. Notably, the C-core SFPM generator achieved a power per PM volume of 24,979 kW/m3, positioning it as the second-highest performing PM generator among all SOTA generators. Lastly, a prototype of the 6-phase 12-stator/25-rotor C-core SFPM generator was manufactured and tested to validate the analytical design.