Finite element analysis and calculation of the magnetic field distribution in smoothing inductors for electric traction

Design criteria for air-core and iron-core smoothing reactors for chopper drivers for electric traction are presented. The systematic use of a commercially available program for finite element analysis of the magnetic field provides a highly useful tool for verifying on a computer, i.e. in a relatively economical way, the effectiveness of the design choices and avoiding costly experimental verification on prototypes. The magnetic field analysis suggests the best orientation of the winding strap in order to limit the eddy-current loss and provides a design solution for the core. Suggestions for the design of the electromagnetic shields to limit the influence of the variable magnetic field outside the reactor are given. Results of experimental tests are reported