Naoto Tagawa

Preliminary design of magnetic shielding by FEM

In this paper, we propose an optimization method for magnetic shielding. Our main purpose is the weight reduction of shield material. Assuming that the permeability of shield material is infinite, we simplify the magnetic shielding problem. Under this assumption, we design optimal passage for magnetic flux through the shield. We apply this method to designing the magnetic shielding for Maglev and show the effectiveness of this method by experimental and numerical data.

Reduction of magnetic field in vehicle of superconducting maglev train

For EDS (electrodynamic suspension) maglev trains, magnetic shielding is an important task. We have attained a field of less than 2 mT. In this study, we tried to reduce the magnetic field level in vehicles further (less than 0.5 mT) by suitable choice of shielding material and shielding structure according to each part on vehicles.

Verification of insulation tests for traction motors

More than 30,000 thousand dc motors are used by the Japan Railway group companies alone as traction motors for railway vehicles. Insulation breakdown of armatures is one of the most important problems in traction motors. Therefore, various insulation tests are carried out for each motor in overhaul. The methods for insulation tests were determined more than 30 years ago. As insulating materials and the method to compose these materials have progressed in recent years, it is important to research what kinds of insulation tests are suitable for traction motors. We estimated the effects of various insulation tests by carrying out insulation breakdown tests for more than 150 motors. This paper describes the results of the study.