Comprehensive analytical modeling framework for inertial wave energy converters: Theory, simplification, and case study

Wave energy converters (WECs) using inertial reaction mass (IRM) systems integrate a reacting mass within the floater, coupled with a power take-off (PTO) system, to protect electronic components from the harsh marine environment. However, the inclusion of IRM systems introduces additional complexity to WEC modeling, since the description of the dynamics of the internal inertial body and its coupling with the floater is required, alongside the traditional WEC modeling challenges, such as hydrodynamics and PTO representation. The literature presents various IRM WEC systems involving technologies such as pendulums, gyroscopes, and sliding masses in various configurations. Therefore, this work addresses the modeling challenges by offering a comprehensive approach for the mathematical representation of these systems. In particular, the proposed framework systematically captures the mechanical dynamics of IRM devices, facilitating the development of simplified nonlinear models and their subsequent linear approximations. In this context, linear models enhance dynamic analysis by highlighting the coupling between hydrodynamic modes and the distinct motions of various inertial body technologies. To ensure versatility, the modeling procedure is kept general to ensure its adaptability to a wide range of IRM WECs. A case study focusing on vertical-sliding mass WEC is presented to demonstrate the methodology's effectiveness. Furthermore, the analytical framework's reliability is validated through comparison with results from commercial software, highlighting its practicality and accuracy.