This dissertation looks into a type of magnetic gear, referred to as the Trans-Rotary Magnetic Gear (TROMAG), for reciprocating Wave Energy Converters (WECs). A TROMAG consists of two main parts: a translator that is coupled, mechanically or magnetically, to a buoy and a rotor that is coupled to a rotary generator. The device accomplishes two tasks: it converts linear motion to rotation (and vice versa) through magnetic fields, and at the same time it does a gearing action. This means that it can convert the high-force, low-speed linear motion of a buoy to a low-torque, high-speed rotation, which enables using a compact, high-speed rotary generator. As a magnetic gear, the TROMAG offers contact-free force transmission and its consequent advantages such as reduced wear and tear, reduced need for lubrication and maintenance, high reliability, and inherent overload protection capability. In this dissertation, first, the motivation behind developing the TROMAG is presented. Then, the structure of the device and its principles of operation are laid out. Moreover, aspects of magnetic design are studied by using either an analytical model, three-dimensional (3D) finite element analysis (FEA) or two-dimensional (2D) FEA. It is shown that, for a high-force, low-speed load characteristic, a system comprising a TROMAG and a rotary machine would far surpass a direct drive linear machine (DDLM) designed for the same force and speed, in terms of weight, cost, and volume of the required active material. In addition, a nonlinear analytical model is proposed to describe the dynamic behavior of the TROAMG. The model is then linearized and combined with the linearized model of a buoy in order to study the dynamics of the entire wave energy conversion system. Furthermore, a demonstrative prototype of the TROMAG is constructed and tested to verify the theoretical concepts and employed analyses.
