Performance evaluation of slip couplers with spoke- and surface-mounted PM for wind energy applications

In this study slip permanent magnet couplers (slip-PMC) for wind turbine application are introduced and their analysis technique used in finite element method (FEM) is presented. Two optimization methods are employed in determining optimum permanent magnet (PM) rotors for a fixed wound rotor size. The machine topologies, namely surface-mounted and spoke-mounted PM rotor topologies are evaluated against each other. The machine topologies are modeled and simulated by means of a static FEM-based calculation method and a transient state FE package in order to capture the skin effect and observe how it impacts the performance prediction. The measurements of a reference slip-PMC machine are presented to demonstrate the validity of the concept. The optimum design results from the optimization methods for the spoke-mounted magnet slip-PMC are presented as well as the performance results of the surface-mounted magnet machine. It is shown that the spoke-mounted magnet slip-PMC has improved performance compared to the surface-mounted magnet slip-PMC in terms of torque per active mass.