Optimization and Performance Evaluation of Non-Overlap Wound-Field Converter-Fed and Direct-Grid Wind Generators

• Published in: IEEE access Vol. 10; pp. 40587 - 40595
• Main Authors: Garner, Karen S., Akuru, Udochukwu B., Kamper, Maarten J.
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aspect ratio; Converter-fed; Design optimization; direct grid-connected; finite element analyses; Finite element method; Generators; Global optimization; medium-speed wind generators; non-overlap winding; Optimization; Performance evaluation; Permanent magnets; Powertrain; Rotors; Stator windings; Synchronous machines; Torque; Wind power generation; Windings; Windpowered generators; wound rotor synchronous machine (WRSM); wound-field flux switching machine (WF-FSM)
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2022.3167148

Non-overlap winding technology continues to remain relevant in the design of wound-field machines as an alternative for high torque density permanent magnet machines. In this paper, the finite element analyses-optimisation of two variants of the non-overlap wound-field machines viz., wound-field flux switching machine (WF-FSM) and phase shifting wound rotor synchronous machine (WRSM), are compared, first in terms of their performance for large-scale converter-fed wind generator drives, then experimentally as sub-scaled converter-fed versus direct grid-connected wind generators, respectively. This study is unique because there are no prior attempts to design, optimize and analyse on these machines for medium-speed wind power generation, as well as experiment on sub-scale prototypes for direct-grid and converter-fed operation. All investigations are contemplated in the medium-speed wind generator drivetrain which provides a tradeoff for generator efficiency and size. From the global optimisation of both machines at large-scale power levels, the torque per mass of the WF-FSM is found to be 50 % lesser compared to the WRSM. This is due to approximate volume, with closely matched optimal split and aspect ratios. In terms of the sub-scaled experimentation, both generators can easily vary their generated output power to match with varying wind resource, but direct grid-connected WRSM generator yields better efficiency performance compared to the WF-FSM converter-fed operating mode, given that the generator terminal voltage of the former is highly regulated.