The Dual-rotor Wind Turbine Permanent Magnet Research

Wind energy is renewable resource. More and more experts began to put an emphasis on permanent machine with high efficiency for wind energy system. Supported by Shandong Science and Technology Development, This thesis study an novel machine—the dual-rotor radial-flux permanentmachine. Because of it's high efficiency and special structure, it hasa big advantage on the small wind energy system. The research of the thesis mainly includes the following points:In the first part, the structure,Equivalent magnetic circuit model and the principle of the machine is discussed. Then compute the inductance of the dual-rotor permanent machine.The second part gives the permanent magnet emf of analytical method and finite element analysis. First of all, considering the stator slot, the no-load air-gap magnetic flux distribution and the permanent emf can be expressed by using air-gap relative permeance function, and then give the corresponding waveform. Secondly, the permanent EMF is inferred using a Method of Vector Synthesis . In order to check the analytical method, a finite element analysis is implemented to study the air-gap magnetic flux distribution and the permanent emf. Through the comparison, the analytical method and the finite element analysis are in good agreement. At last, the thesis presents three methods to reduce the permanent emf fluctuation using the theoretical analysis, proves the methods are feasible.The third part analyzes the permanent emf and the cogging torque of the halbach machine, because the halbach machine has a great advantage on the wind energy system. First of all, the principle of the halbach array is presented. Secondly, a finite element analysis is implemented to study the air-gap magnetic flux distribution and the permanent emf. At last, the thesis calculates the cogging torque using electromagnetic software. The thesis presents three methods for reducing cogging torque fluctuation to the halbach array dual-rotor machine, through the finite element analysis, the methods are proved to be feasible.The forth part discusses the design thought, bringing forward thought that we can design the inner and outer part respectively, and then adjust the two parts of the machine generally, we give the mode of the machine and make some experiment. We measure the permanent emf waveform at different speed,voltage—speed curve,voltage—current characteristic curve on the load and measures the inductance of armature reaction. Through the comparison , the value of experimental,theoretical and finite element analysis are in good agreement.