Study of wind turbine blade fatigue testing based on electromagnetic compound excitation

In view of the large disturbance caused by bi-directional fatigue loading and the large inertia of the blade leading to the difficulty of control and the failure of precision, a new electromagnetic compound excitation method for wind turbine blade biaxial fatigue test is proposed. According to the actual working conditions, the influence of electromagnetic mechanism parameters on the characteristic of excitation force are studied, and the mathematical model of electromagnetic fatigue loading system is established with solenoid type electromagnet as the loading device. The multi-stage electromagnetic excitation force is designed and the relationship between the electromagnetic force and the amplitude and frequency of the blade is obtained based on the law of conservation of energy. The magnetic field calculation model has been simulated in the ANSYS Maxwell to analyze the influence of electromagnet structural parameters on loading force and speed. Furthermore, the optimal selection range of coil turns, shape parameters, core length and outer diameter of the electromagnetic mechanism that meet the test requirements under the given blade specifications is obtained, which lays a theoretical foundation for the subsequent development of the electromagnetic fatigue loading test bench.