What is a magnetic encoder and what are its advantages and disadvantages

Magnetic encoders do not need complex code discs and light sources, the number of components is less, and the detection structure is simpler; at the same time, the Hall element itself also has many advantages, such as: firm structure, small size, light weight, long life, shock resistance It is not afraid of pollution or corrosion by dust, oil, water vapor and salt spray...etc. Magnetic encoders also have relatively high reliability in use, are strong and durable, and are suitable for use in some relatively harsh equipment environments, such as wind power, construction machinery, etc.

Magnetic encoder is a new type of angle or displacement measuring device. Its principle is to use magnetoresistance or Hall element to measure the angle or displacement value of the changing magnetic material. The change of the angle or displacement of the magnetic material will cause a certain resistance or voltage. The change of the signal is amplified by the amplifying circuit, and the pulse signal or analog signal is output after being processed by the single-chip microcomputer to achieve the purpose of measurement. Its structure is divided into two parts: sampling detection and amplifying output. Sampling detection is generally completed by bridge circuit, there are two kinds of half bridge and full bridge, and the amplified output is generally realized by devices such as triode and op amp. Compared with traditional photoelectric encoders and grating encoders, magnetoelectric encoders have the characteristics of anti-vibration, anti-corrosion, anti-pollution, anti-interference and wide temperature, and can be used in fields that traditional photoelectric encoders cannot adapt to. High-performance magnetoelectric encoders can be widely used in industrial control, machinery manufacturing, ships, textiles, printing, aviation, aerospace, radar, communications, military and other fields.

Magnetic encoders also have some specific disadvantages. For example: susceptible to electromagnetic interference, need to take compensation and protection measures to avoid temperature drift...

The most important of these is its (lower than optical encoder) accuracy and resolution. At present, the general magnetic encoder can achieve a single-turn 13-bit resolution, although a manufacturer has been able to achieve a single-turn 17-bit resolution in this regard, but this is only a relatively common optical encoder has achieved. level only. Therefore, the current magnetic encoders are more suitable for application scenarios, perhaps some of the more general position and speed detection links, rather than those high-performance transmission and motion control systems, especially the transmission control loop feedback.

Another disadvantage of magnetic encoders that is often criticized by everyone is its slow response speed, which cannot be used for position feedback of high-speed motion loads. It is considered not suitable as an integrated position feedback element in a servo motor; in addition, as a servo encoder, there is another problem that must be solved, that is, multi-turn position feedback