There are various detection methods, from using electromagnetic induction from a pickup coil to using the Hall effect or the magneto resistive effect. The latter methods have begun to be used in recent years because they can obtain a signal corresponding to the magnitude of the magnetic flux density regardless of the frequency.
To predict the signal produced in a sensor by the magnetic flux density generated at the sensor position and apply it to the displacement and speed control of the mover, electromagnetic field analysis that can accurately calculate the magnetic flux density and magnetic field distribution generated from the analysis target is useful.
In this example, with the analysis target being a motor and the detection sensor being a TMR sensor, an example where a detection signal waveform is obtained that is based on magnetic field values computed from electromagnetic field analysis is presented.
Magnetic Field Radial Component at the Sensor Position
Resistance Change Rate of Each Sensor
When the current changes, it can be confirmed that the percentage change in resistance shifts to a lower rotation angle, and it can be seen that the relationship between the field strength and the position of the motor changes with the current amplitude. It can be seen that it is necessary to ascertain the relationship between the sensor output and the rotor position when the current changes in order to detect the rotor position accurately.