Sensor cores: the diverse world of materials and structures

The world of sensor cores is rich and colorful. From the perspective of materials and structures, it presents a “pluralistic world”. Different materials and structures give sensor cores different characteristics, enabling them to adapt to various complex application scenarios.

From the material point of view, common sensor core materials include ferrite, silicon steel sheet, Permalloy and iron powder core, etc. They each have their own advantages and disadvantages and play a unique role in different fields.

Ferrite: It is a ferromagnetic oxide with Fe₂O₃ as the main component. As you can imagine, it is like an “economical player” with easy molding, low cost, and low loss in high-frequency environments. However, it also has its own shortcomings, with low saturation flux, so it is more suitable for use in lower frequency and power scenarios, such as some simple electronic devices.

Silicon steel sheet: This is an iron-silicon alloy formed by adding a small amount of silicon to pure iron. It is like a “strongman” with a high saturation flux and can withstand a large magnetic field strength. However, its resistivity is low and the eddy current loss is large in a high-frequency environment, so it is more suitable for low-frequency, high-power applications. It can often be seen in equipment such as large transformers and motors.

Permalloy: As an iron-nickel alloy, it is a “high-precision player” with the advantages of high magnetic permeability and low hysteresis loss, and can provide very accurate measurement results. However, its cost is relatively high, like an expensive luxury item, and its current application is relatively small, mainly used in some special fields with extremely high precision requirements.

Iron powder core: It is made of ferromagnetic powder and insulating medium. Its magnetic permeability is relatively stable with the change of frequency and DC current, just like a “steady veteran”, and it performs well in applications such as filtering and energy storage inductance with high-frequency components superimposed on power frequency or DC.

From a structural perspective, sensor cores can be divided into winding, plate, Hall, and fluxgate types. Among them, the fluxgate current sensor is very unique. It uses the nonlinear relationship between the magnetic field generated by the measured current and the high permeability core under alternating magnetic field saturation excitation to measure the current. This unique measurement method gives it high sensitivity and measurement accuracy, just like a “precise sniper” that can accurately capture changes in the target current in a complex electromagnetic environment.