Analysis and performance of eddy-current brakes with ferromagnetic loss drums. Part 2: Salient-pole brakes

Theories based on fundamental quantities are shown to be inadequate for salient-pole brakes. An analysis, taking into account the distortion of the airgap flux as well as the nonlinearity of the B/H curve of the drum material, is then given. A closed-form solution is obtained for the case when the B/H curve is limiting nonlinear. For the case when the B/H curve has a constant, nonzero slope in the saturated region, a numerical method of solution is proposed. The results of the analysis are presented in normalised form and can be used to predict the performance of brakes with different dimensions and loss drums. The predicted values in the case of experimental machines are found to be in good agreement with test results. One important finding of the analysis is that the slope of the B/H curve in the saturated portion should be as small as possible in order to obtain the highest brake force at all speeds. (See also companion paper: IEE Proc. B, Electr. Power Appl., 1982, 129, (3), pp. 125??131.)