Study of the Counterclockwise/Clockwise (CCW/CW) Rotational Losses Measured with a Two-dimensional Vector Magnetic Property Measurement System

In the development of high-efficiency actuators, high-magnetic flux density conditions are applied to achieve higher torque, lower weight and smaller size. It is therefore very important to understand the magnetic properties under high-magnetic flux conditions in the electrical steel sheets. However, it is very difficult to measure the two-dimensional vector magnetic properties under high-flux density conditions due to nonlinearity and anisotropy of the magnetic materials. The measured magnetic power loss under clockwise rotating fields differs from that of the counter-clockwise direction, and the value in counter-clockwise rotating fields sometimes becomes negative. It can be considered that angle errors of H-coils and B-coils are the main causes of the measurement errors. In this paper, the angle errors of the double B-coil (search coils) and the double H-coil (cross-type H-coil) are evaluated with a projector-type magnifying scope and a calibration device. We have compensated the measured magnetic field vector components caused by the angle errors and made clear their influence on the two-dimensional vector magnetic property measurements. Furthermore, we proposed a method to cancel out small angle errors that remained in the saturated region. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.