Visualization of Current Paths by High-Frequency Magnetic Fields Using the Down-Conversion Method

Abstract

Subsurface magnetic imaging using the electromagnetic field reconstruction is a non-destructive evaluation methods for electric components and circuits. Subsurface magnetic imaging has a considerable limitation because the resolution depends on both the measurement distance and sensitivity of magnetic sensor. In principle, it is difficult to evaluate electronic components and circuits with currents that exceed the response frequency of the sensor. In this study, we propose a down-conversion method for the magnetic field distribution and electric current path images of an isolated DC-DC power conversion circuit, with currents exceeding the response frequency of the magnetic sensor. The circuit was measured with a connected resistance and open circuit condition. The magnetic field distribution and the current path images accurately show that the magnetic field transferred the energy from the input side to the output terminal. Furthermore, the electric current path image shows that there is no electric current flow to the output when the terminal was in open circuit condition.