Analysis on Levitation Force Characteristics of Axial-Flux Hybrid-Excitation Generator for Offshore Vertical Axis Maglev Wind Turbine

Vertical axis wind turbine is gradually playing a great potential in offshore floating wind power generation system. In order to improve the starting performance of vertical axis wind turbine, an asymmetric-primary axial-flux hybrid-excitation generator (APAFHG) for offshore vertical axis maglev wind turbine is proposed. However, the complexity of the controllable levitation force makes it difficult to control the generator. In this paper, the levitation force characteristics of APAFHG under different currents are analyzed and the mathematical model of levitation force is derived. First, the topology and operation principle of APAFHG are introduced, Second, the levitation force performance of APAFHG under DC excitation, d-axis and q-axis current is obtained by finite element method, and the characteristics of levitation force are analyzed with the change of applied current. Finally, the mathematical model of APAFHG levitation force is deduced and verified. The results show that the characteristics and the mathematical model of levitation force can play an important role in the control of levitation force and the decoupling control of power and levitation force.