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Last Updated 2016-06-27

102 - Magnetic Field Analysis of a Magnetic Sensor102 - Magnetic Field Analysis of a Magnetic Sensor
With recent improvements in the functionality of electric devices and home appliances, magnetic sensors are being used more for contactless sensing of whether device doors, etc. are open or closed. An open/closed switch using a magnetic sensor switches between open and closed by sensing distance according to the size of the magnets' magnetic field. At the design stage, it is necessary to evaluate magnet type and position, sensor sensitivity, and other issues.
Magnetic field analysis simulation using the finite element (FEM) method is effective for accounting for differences in magnetic field strength due to three-dimensional positioning and interference from other magnetic parts.
This Application Note presents how to obtain the magnetic flux density distribution at points in the horizontal and vertical directions away from the magnet.
28 - Magnetic Field Analysis of a Speed Sensor 28 - Magnetic Field Analysis of a Speed Sensor
Module:TR 2013-10-28
Antilock brake systems (ABS) have become a standard feature in vehicles, so speed sensors are attached to each wheel in order to measure their respective speeds. There are several methods of detecting rotation speed, but magnetic sensors are weather resistant and have a small number of parts because there only needs to be a gear on the rotation side, so they are widely used.
The challenges from a design standpoint are the angle and relative distance between the gear's teeth and sensor, and how to ensure sensitivity and responsiveness when considering the magnetic influence of the surrounding air. In order to proceed with an advance study like this that considers a precise geometry and material properties, an electromagnetic field analysis using the finite element method (FEM) is effective.
This Application Note presents the use of magnetic field analysis to evaluate the variation of the voltage signal of a magnetic speed sensor for a range of air gap distances.

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