Optimization Design of Cross-Winding Transverse Flux Linear Generator for Wave Energy Conversion
Chen Minshuo1, Huang Lei2,3, Qin Wei2,3, Li Yuan2, Yang Jianlong2
1. School of Electric Power Engineering Nanjing Institute of Technology Nanjing 211167 China; 2. School of Electrical Engineering Southeast University Nanjing 210096 China; 3. Advanced Ocean Institute Southeast University Nantong 226010 China
Abstract：Wave energy constitutes a significant component of marine renewable energy, characterized by its vast reserves and widespread distribution. Compared to wind and solar energy, wave energy exhibits higher power density and better predictability, presenting immense development potential and promising utilization prospects, thus emerging as the most prioritized and promising marine renewable energy source. The average wave power density along China's coastlines can reach 2 kW/m to 7 kW/m. Developing efficient and low-cost wave energy conversion technologies aligns with global energy development trends and China's national strategic needs, while also addressing coastal power shortages and facilitating off-grid electricity usage in maritime areas. Among various wave energy conversion devices, the direct-drive wave energy conversion (DDWEC) system stands out by eliminating intermediate transmission mechanisms and utilizing linear generators to capture and convert wave energy. It offers advantages such as high efficiency and low cost. However, due to the relatively low velocity of ocean waves, the wave generator is bulky. Researchers worldwide have been utilizing different types of linear generators in direct-drive wave energy conversion systems. The transverse flux linear generator (TFLG) features a central magnetic flux path plane perpendicular to the secondary motion direction. Electrical and magnetic loads can be decoupled, facilitating the increase of machine output power by augmenting the number of pole pairs. It is particularly suitable for low-speed, high-torque/thrust applications. In comparison to longitudinal flux linear machines, TFLG, with an axially laminated structure, effectively blocks eddy currents, reduces eddy current losses, and enhances power generation efficiency. It offers advantages in terms of volume, mass, and efficiency, making it an excellent choice for wave linear generators. This paper introduces a cylindrical transverse flux linear generator featuring circumferential and axial interlaced winding connections, as well as a hybrid excitation structure. By altering the magnetic circuit orientation and employing axial lamination, the proposed design effectively reduces eddy current losses and enhances power generation efficiency. This paper outlines the generator structure, operating principle, and winding connection method. A general expression is derived for the back electromotive force (EMF) applicable to any individual coil. By adjusting the permanent magnet orientation, coil current direction, and axial distance difference, arbitrary amplitude and phase back EMF can be achieved. Subsequently, the paper investigates the impact of different pole-slot combinations and phase winding configurations on average thrust and thrust ripple. Compared to circumferential three-phase and axial three-phase structures, the proposed design exhibits a lower thrust ripple (2.62%) and a higher average thrust force (227.38 N), with a power density of 7.841 kW/m3 per unit volume. The proposed generator features a hybrid excitation structure, which accommodates varying wave velocities, enabling wide-range magnetic field adjustment, minimizing voltage drop under load, and achieving superior power quality. A prototype based on the optimized design parameters was manufactured, and a direct-drive wave energy conversion simulation experiment platform was established. Experimental results closely aligned with finite element simulation results.
陈珉烁, 黄磊, 秦伟, 李渊, 杨建龙. 波浪发电用交叉绕组横向磁通直线发电机优化设计[J]. 电工技术学报, 2025, 40(20): 6446-6459.
Chen Minshuo, Huang Lei, Qin Wei, Li Yuan, Yang Jianlong. Optimization Design of Cross-Winding Transverse Flux Linear Generator for Wave Energy Conversion. Transactions of China Electrotechnical Society, 2025, 40(20): 6446-6459.
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2025, Vol. 40 
