Control-inspired design and power optimization of an active mechanical motion rectifier based power takeoff for wave energy converters

Journal Article · 06 May 2024 · Renewable Energy

DOI: https://doi.org/10.1016/j.renene.2024.120614 · OSTI ID:2403436

Yang, Lisheng  ^[1]; Huang, Jianuo ^[2]; Mi, Jia ^[2]; Hajj, Muhammad  ^[3]; Bacelli, Giorgio ^[4]; Zuo, Lei ^[2]

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1. University of Michigan, Ann Arbor, MI (United States); University of Michigan, Ann Arbor
2. University of Michigan, Ann Arbor, MI (United States)
3. Stevens Institute of Technology, Hoboken, NJ (United States)
4. Sandia National Laboratory (SNL-NM), Albuquerque, NM (United States)

Ocean waves have high energy density and are persistent and predictable. Yet, converting wave energy to a useable form remains challenging. A significant hurdle is the oscillatory nature of waves resulting in the alternating loads, which necessitate the use of rectification at some stage of the energy conversion. This research effort presents a novel design of active mechanical motion rectifier (AMMR) for the power takeoff (PTO), which provides enhanced controllability and better power performance when compared to passive mechanical motion rectifiers (MMR). Inspired by transistors used in synchronous electrical rectifiers, the proposed design uses controllable electromagnetic clutches in the mechanical transmission to allow active engagement-disengagement control; thus, rectifying the oscillatory motion into a unidirectional rotation for high energy conversion efficiency and allowing the generator in unidirectional rotation to control the bidirectional wave capture structure for maximizing the power output. A semi-analytical computational approach is developed to efficiently evaluate the optimal power achieved using the proposed AMMR-based PTO and active control. It is found that the AMMR-based PTO design yields a higher optimal power than the previous passive MMR design across the wave spectrum. The influences of generator inertia and reactive power are discussed. Furthermore, the effects of control parameters on the power output and the optimal trajectories are analyzed. Wave tank tests with the AMMR prototype demonstrated the effectiveness of AMMR based PTO design and validated the numerical analysis.

• Research Organization: Stevens Institute of Technology, Hoboken, NJ (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Water Power Technologies Office
• Grant/Contract Number: EE0008953; NA0003525
• OSTI ID: 2403436
• Journal Information: Renewable Energy, Journal Name: Renewable Energy Vol. 228; ISSN 0960-1481
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English