Two-Segment Magnet Transverse Flux Ferrite PM Generator for Direct-Drive Wind Turbine Applications: Nonlinear 3-D MEC Modeling and Experimental Validation

Abstract

Transverse flux PM generator (TFPMG) is a capable option for direct-drive wind turbine (DDWT) applications due to its high-power characteristics at low speeds. NdFeB-based TFPMGs may suffer from a higher total cost and lower thermal capabilities compared to the ferrite-based TFPMGs. Not yet covered in the existing literature, in this paper a transverse flux ferrite PM generator (TFFPMG) is proposed, designed, and modeled, which can also resolve the unipolar flux generation and even-order harmonics in the flux linkage of the conventional TFPMGs that occurred in conventional TFPMGs through its innovative two-segment trapezoidal shape magnet structure. Due to the 3-D flux path nature in the proposed TFFPMG, either 3-D finite element analysis (FEA) or 3-D magnetic equivalent circuit (MEC) modeling should be used. As a computationally efficient modeling method, a nonlinear 3-D MEC is established to model the entire structure of the TFFPMG while the core saturation and nonlinear permeances are also fully considered to improve the modeling accuracy. The electromagnetic performance of the proposed TFFPMG modeled by 3-D MEC in various loading conditions is validated by both 3-D FEA and experimental results using a 2.5 kW TFFPMG. A close agreement between 3-D MEC modeling predictions, 3-D FEA, and test results confirms the reliability of the MEC modeling for the proposed TFFPMG.