Recently, electrical power generation from oceanic waves is becoming very popular, as it is prospective, predictable, and highly available compared to other conventional renewable energy resources. In this paper, various types of nearshore, onshore, and offshore wave energy devices, including their construction and working principle, are explained explicitly. They include point absorber, overtopping devices, oscillating water column, attenuators, oscillating wave surge converters, submerged pressure differential, rotating mass, and bulge wave converter devices. The encounters and obstacles of electrical power generation from the oceanic wave are discussed in detail. The electrical power generation methods of the generators involved in wave energy devices are depicted. In addition, the vital control technologies in wave energy converters and devices are described for different cases. At present, piezoelectric materials are also being implemented in the design of wave energy converters as they convert mechanical motion directly into electrical power. For this reason, various models of piezoelectric material-based wave energy devices are illustrated. The statistical reports and extensive literature survey presented in this review show that there is huge potential for oceanic wave energy. Therefore, it is a highly prospective branch of renewable energy, which would play a significant role in the near future.

Recently, electrical engineers are paying great attention to develop oceanic wave energy conversion technologies based on the piezoelectric materials because of their excellent conveniences. Piezoelectric oceanic wave energy converters (OWECs) have several benefits over the others such as its small size, lightweight, no requirement of using intermediate device as well as having less negative impacts on the oceanic environment. Various review and research papers focus on the piezoelectric devices, their operation and application for oceanic energy conversion. But, to the best of the authors' knowledge, none of the existing research or review papers present detailed scheme of piezoelectric device based power generation covering all the relevant topics as depicted in this review. This paper focuses different aspects of piezoelectric device based oceanic wave energy conversion technology including prospect, historical development, classification, operating principle, configuration, arrangement, model, processing, post-processing, and their test setups. In addition, technical challenges, future direction of research and critical review are also illustrated. It is assumed that, this paper would play a significant role for the future development of piezoelectric OWECs and the researcher working in this field. INDEX TERMS Energy conversion, oceanic wave energy, piezoelectric material, piezoelectric generator, renewable energy, wave power.

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The oceanic wave energy generation has been drawn significant attention in the field of power engineering recently. These generation systems are basically direct drive electrical power generators connected to the wave energy devices with the variable frequency drives (VFDs). This study proposes an application of high-frequency transformers at the output stages of VFDs for the galvanic isolation purpose among multiple output ports of VFDs in a wave farm. The design process of a highfrequency magnetic link involves multiphysics problems that entail complex tradeoffs between electrical and magnetic properties including efficiency. Moreover, the performance of the magnetic link depends on the switching characteristics of the power switching devices and various excitation signals. Therefore, extensive multiphysics research in the field of design and optimisation of magnetic links is needed to develop next-generation technologies. In this study, a finite-element method-based systematic process is presented for the design of amorphous alloy-based core of the high-frequency magnetic link. Two cores are developed and characterised in the laboratory. The characterised data obtained from the experiment can be used in the future design optimisation of other high-frequency magnetic links.

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