Characteristics of hall sensor
The essence of the Hall effect is that when carriers in solid materials move in an external magnetic field, the trajectory shifts due to the Lorentz force, and charges accumulate on both sides of the material, forming an electric field perpendicular to the current direction. Finally, the Lorentz force on the carriers and the repulsive force of the electric field reach a balance, thus establishing a stable potential difference on both sides, that is, Hall voltage. The ratio of the product of orthogonal electric field and current intensity to magnetic field intensity is Hall coefficient, and the ratio of parallel electric field to current intensity is resistivity. A large number of studies show that not only negatively charged electrons, but also positively charged holes also participate in the conductive process of materials.
Hall-type speed sensor belongs to Hall-type sensor, which is made by using the principle of Hall effect. Hall-type speed sensor is a sensor which uses Hall effect to make displacement drive Hall element to move in magnetic field to generate Hall heating, that is, to convert displacement signal into electrothermal change signal. Hall speed sensor is a small closed sensor, which has the advantages of stable performance, low power consumption, strong anti-interference ability and wide temperature range. The principle is that the Hall potential generated when the magnetic field lines pass through the sensitive elements on the sensor is amplified and shaped by the Hall chip, and then the generated electrical signal is used by the secondary instrument. When in use, as long as a small piece of magnetic steel is attached to a rotating object, the sensor is fixed within a certain distance from the magnetic steel and aligned with the S pole of the magnetic steel, the measurement can be carried out.
In the use of Hall element, there are many factors that affect the measurement accuracy. The main reasons are two kinds of semiconductor manufacturing processes and the inherent characteristics of semiconductors, which are manifested as zero error and measurement error caused by temperature. Hall speed sensor has several different structures. The input shaft of the magnetic turntable is connected with the rotating shaft to be measured. When the measured rotating shaft rotates, the magnetic turntable rotates accordingly. The Hall sensor fixed near the magnetic turntable will generate corresponding pulses when each small magnet passes by, and the measured rotational speed can be known by detecting the number of pulses per unit time. The number of small magnets on the magnetic turntable determines the resolution of the sensor to measure the speed.