Design and Airgap Flux Density Calculation of Dual-Rotor Permanent-Magnet Wind Generator

Dual-rotor permanent-magnet wind generators can substantially improve the utility of wind power even at a low wind speed due to its high relative speed between the magnetic field and windings. This paper briefly introduces its principle and structure, establishes its equivalent magnetic circuit based on the open-circuit flux distribution of the designed motor, and then calculates the airgap flux density, which takes into account the slotting effect, saturation in magnetic bridges, airgap and end leakage. In addition, the finite-element method and a prototype were employed to verify the analytical method. The agreements were obtained among the values of the analytical method, finite-element analysis and tests results, thus proving the feasibility of the calculated method and the design.