Optimal gear ratio selection of linear primary permanent magnet vernier machines for wave energy applications

Reza Jafari, Pedram Asef, Pouria Sarhadi, Xiaoze Pei

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Linear permanent magnet vernier generators offer a high capability of force density, making them appealing configurations for wave energy harvesting systems. In absolute terms, the performance of these machines is significantly influenced by the selection of slot/pole combinations based on the magnetic gearing effect. For the first time, this paper aims to investigate the impact of different gear ratios on a wide array of linear primary permanent magnet vernier machines (LPPMVMs) with different slot/pole combinations based on fair criteria to offer a more comprehensive understanding of gear ratio selection. To find the optimal number of slots and poles, the response surface methodology is adopted to obtain a robust design and make a fair comparison among LPPMVMs with optimum design characteristics using a cost‐effective approach for the fast and reliable optimisation process. The higher gear ratios result in higher thrust force capability. This will help establishing a new route toward faster develpment of advanced LPPMVMs. The power loss models of LPPMVMs are studied to predict their steady‐state and transient thermal behaviours, verifying their stability and safety, while a simple external forced convection method can be utilised. To verify the model, finite element analysis is exploited to confirm the electromagnetic and thermal analysis results and provide a more exhaustive investigation.
Original languageEnglish
Pages (from-to)1-16
Number of pages16
JournalIET Renewable Power Generation
Early online date16 Nov 2023
Publication statusE-pub ahead of print - 16 Nov 2023


  • wave and tidal energy
  • electric power generation
  • electromagnetic devices
  • electric machine analysis computing
  • energy harvesting
  • renewable energy power conversion
  • wave power generation
  • AC generators
  • optimisation
  • electric generators


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