Eddy current heating in large salient pole generators
Purpose - The purpose of the paper is to investigate pole face heating in large, salient pole generators and establish a modelling procedure for accurate rotor pole heat loss computation using finite element analysis. Design/methodology/approach - Finite element-based simulations of the dynamic electromagnetic problem in an idealized 60 Hz, six-pole, three-phase generator were carried out, including coupling to three-dimensional finite element thermal analysis. Findings - T'he effect of trailing pole face heating was effectively demonstrated. Accurate estimates of the ventilation and convective cooling were shown to be particularly important. Research limitations/implications - Accurate heat transfer values could only be obtained using a very sophisticated model in a computational fluid dynamics analysis software package. The complexity of the stator end winding alone makes this a daunting challenge, without the inclusion of the rotation effects and stator cooling ducts. At this stage, it was deemed more useful to use the thermal analysis to observe trends. Practical implications - Three-dimensional effects are significant and require modelling. However, obtaining steady state behaviour using a 3D analysis is probably not viable yet. The synchronous operating conditions were obtained from a two-dimensional analysis and used as the initial conditions for a full 3D analysis. Originality/value - The paper has helped to enhance the understanding of pole face heat loss in large salient pole synchronous generators, fully examining the mechanisms causing the heating. A complete procedure to achieve this task in a realistic time frame using sophisticated finite element analysis tools has been proposed.
eddy currents heating finite element analysis