Dynamic Magnetization Measurement System for Soft Magnetic Materials

In this work, the dynamic magnetization measurement system for characterizing the soft magnetic core materials of a fluxgate sensor is investigated. The alternating magnetizing field is generated by a solenoid coil. The reduction in field strength caused by the inductive reactance is overcome by cascading a proper metal film capacitor to the magnetizing coil to form a tank circuit. The pickup coil, which consists of inversely connected sensing and reference solenoids, is mounted inside the magnetizing coil to null the background output. The output response of the sample is converted into the magnetization signal by using a digital or analog integrator. It is found that the magnetizing curve of a ferrite cylinder shows the frequency-independent apparent susceptibility, which can be used as the standard for calibrating the dynamic magnetization measurement system. Experimental results show that the conversion factor for magnetization measurement remains constant up to 5.1 kHz with a digital integrator. The magnetization curves are low hysteresis with a consistent apparent susceptibility for the amorphous samples up to kilohertz frequencies, while nickel and mu-metal samples are generally hysteretic in the dynamic magnetization process. The proposed system is valuable for exploring the dynamic magnetization response for a variety of soft magnetic materials to construct the numerical model.