Linear generator technologies for wave energy conversion applications: A review

Compared to other renewable technologies, wave energy is more persistent, predictable, and concentrated. This review focuses on the deployment of linear generators, as they proved to be well suited for wave energy conversion. Unlike traditional rotary generators, linear generators can operate at variable speeds of waves and consequently the translator's motion varies in the same direction. Therefore, the generated voltage and current vary in both frequency and amplitude and also the phase sequence keeps alternating, which leads to a significantly higher peak-to- average power ratio. Different types of wave energy converters are briefly previewed and categorized according to the working principle of the primary capture systems and secondary power take-off systems. Then linear generators are compared in terms of general system configuration, flux path and core type. The comparison is followed by presenting state-of-the-art linear generator topologies with focus on high-temperature superconducting linear machines.