How does the magnetic encoder work?

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The servo control system of the magnetic encoder belongs to the closed-loop control. The basic four links of the closed-loop control are the controller, the actuator, the controlled object, and the detection and transmission. The magnetic encoder mentioned here belongs to the detection and transmission link in the closed-loop control. It is used to detect the magnetic field position of the servo motor rotor, provide accurate motor speed and position signals, and then the magnetic encoder outputs the signal to the driver for analysis, comparison and logical judgment, and then drives the servo motor. In fact, the magnetic encoder is a sensor, which always provides accurate signals to the driver to facilitate it to make accurate analysis and judgment.

Working principle of magnetic encoder: The magnetic encoder adopts magnetoelectric design, and the magnetic field change of the magnetic induction device is used to generate or provide the position and speed of the actuator (servo motor).

The physical working principle of the magnetic encoder is the magnetoresistance effect. The magnetoresistance effect is generated by the internal carriers of the energized conductor or semiconductor, and the external Lorentz magnetic force will cause the internal carrier motion trajectory to deflect or produce spiral motion, thereby changing the potential difference inside the conductor or semiconductor. This process is only a microscopic manifestation. As long as the external magnetic field changes, the magnetic resistance value will also change accordingly. This is the magnetoresistance effect of the magnetic encoder.

The magnetoresistive devices of magnetic encoders include semiconductor magnetoresistive devices and strong magnetic magnetoresistive devices. Therefore, the detection probe of the magnetic encoder uses the magnetoresistive device as the magnetic head. At present, the magnetoresistive device heads commonly used in the probes of magnetic encoders include giant magnetoresistance effect heads (GMR) and anisotropic magnetoresistance effect heads (AMR). However, due to the advantages of AMR heads over GNR heads, such as good frequency characteristics and higher sensitivity, they have gradually become the mainstream application heads of magnetic encoders.

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