Simplified approach to radial flux loss calculation in cylindrical rotor generators

This paper describes a calculational technique developed to calculate the eddy current losses (radial flux losses) induced in the stator conductors of round rotor synchronous generators operating at any desired conditions. Determination of these losses requires accurate modeling of the nonlinear magnetic circuits of the generator in order to obtain the magnetic field distribution in the generator under load. This type of modeling has been done in the past by the use of extensive methematical analog grids which model, with discrete elements, the magnetic response of a cross section of the entire generator. The solution of these grids is often cumbersome and is usually so expensive from the standpoint of computer costs, that the calculational methods are not practical for use as an everyday engineering tool. The analysis described in this paper combines the use of vector potential grid modeling methods with a battery of carefully chosen simplifying assumptions. The result is a calculational technique which is economical and practical enough for widespread use by the machine designer as he explores new designs. The method produces results which agree extremely well with both shop tests on synchronous generators and with the results of more cumbersome computer programs.