Parametric Optimization and Harmonic Analysis on Damper Winding with Direct Time-Step Field and Circuit Coupling Finite Element Method

Traditional magnetic circuit methods conclude that slot magnetic conductivity harmonics modulates main magnetic field in air gap to form additional magnetic field, which generates induced potentials in damper winding. However, slot magnetic conductivity harmonics and additional magnetic field can not be accurately calculated. Direct time-step field and circuit coupling finite element method is proposed to solve the problem, which considers more details of the constraint of damper winding. Parametric optimization is further used to establish damper winding equivalent circuit. Two types of simulations are executed including damper materials and slot pitch angle variation. The proposed method can attain parameters such as flux density and spectrogram diagram on fundamental and high order harmonics. Analysis of simulation results gives the best scheme in the example. It also offers good reference for asynchronous generator squirrel cage structure optimization.