Performance of Linear Generator Designs for Direct Drive Wave Energy Converter under Unidirectional Long-Crested Random Waves

Abstract

For generating electricity, direct-drive wave energy converters (WECs) with linear permanent magnet generators (LPMGs) have advantages in terms of efficiency, simplicity, and force-to-weight ratio over WEC with rotary generators. However, the converter’s work under approaching-real wave conditions should be investigated. This paper studies the performance of a pico-scale WEC with two different LPMGs under unidirectional long-crested random waves. Different significant wave heights (using data in the Southern Ocean of Yogyakarta, Indonesia) and peak frequencies are tested. The JONSWAP energy spectrum is used to extract the wave elevations, while the MSS toolbox in MATLAB Simulink is employed to solve the floater’s dynamic responses. Next, the translator movements are extracted and combined with the flux distribution from FEMM simulation and analytical calculation, and the output powers are obtained. An experiment is conducted to test the output under constant speed. The results show for both designs, different tested significant wave height values produce higher output powers than peak frequency variation, but there is no specific trend on them. Meanwhile, the peak frequency is inversely proportional to the output power. Elimination of the non-facing events results in increasing output power under both parameters’ variation, with higher significant wave height resulting in a bigger increase. The semi iron-cored LPMG produces lower power loss and higher efficiency.

Design and optimization of air‐cored double‐sided linear permanent magnet generators for wave energy conversion

“…in loss out (23) In ( 23), P loss is the loss of the generator, which is expressed by the following equation:…”

“…Currently, most of the generators used for these converters are linear permanent magnet generators (LPMGs). 15 Various types of these generators include tubular [16][17][18] or flat, 19 air-cored 20,21 or iron-cored, 22,23 transverse [24][25][26][27] or longitudinal flux, 28 double-sided 29 or single-sided, which are used in numerous applications. Therefore, much research has been devoted to the analysis, design, and optimization of these types of generators.…”

Geometry Optimization of Heaving Axisymmetric Point Absorbers under Parametrical Constraints in Irregular Waves

“…However, waves in real seas are irregular as a result of their random behavior. Here, an irregular wave is treated as the superposition of regular-wave components with discrete wave frequencies, the amplitude of which is determined from a wave spectrum [22,23]. One of the most commonly used wave spectrums is the Pierson-Moskowitz spectrum, which describes fully developed wind seas and can be expressed as…”