Modelling of insulation in concentrated stator coils for characterisation and material changes

The highly demanding operation of electrical machines in aerospace can lead to the degradation of electrical insulation systems within the machine windings over time. This paper presents a novel method for high frequency modelling of a coil from the concentrated stator winding of an 2MW aerospace generator, for the purpose of characterising the insulation system by the amplitude and phase responses by the Bode plots in the same framework as electrical impedance spectroscopy. This new approach of high frequency model utilises a finite element model, deployed in tandem with an electrical equivalent circuit representation. Matlab is used to quantify the results taken from finite element modelling and implemented into LTSpice, so that the model considers mutual coupling of inductances and high-frequency effects, such as proximity and skin effects. This novel methodology allows extraction of the impedance profile with respect to the material changes within the simulated insulation system.