Magnetic gearbox with an electric power output port and fixed speed ratio for wind energy applications

Mechanical gearboxes are typically employed with doubly-fed induction generator-based wind turbines. The main drawback of this solution is the gearbox´s reliability and maintenance. Using magnetic gearbox in conjunction with the doubly-fed induction generator is an emerging alternative being promoted by the research community which maintains the reduced size doubly-fed machine and overcomes the mechanical gearbox problems reported by field experience. This paper proposes a novel magnetic gearbox configuration in which a conventional planetary magnetic gearbox is equipped with n-phase coils fitted around the ferromagnetic pole-pieces to extract output electrical power. The turbine mechanical power is thus divided into mechanical power to drive the electrical generator and extra electrical power that can be diverted into a storage system to perform the power leveling function. The proposed configuration can also be used to freely modify the power-speed characteristic as seen by the electrical generator, a highly needed feature for grid frequency support.