Tell you how the encoder is classified

Source: Author: ZLG electronic fancier Zhiyuan

[introduction] want to control the motor precision, you will need to use such a thing, because it can help you decipher the rapid rotation of the motor?

In order to control the motor accurately, you will need to use such a thing, because it can help you decipher the fast rotating motor

The photoelectric encoder applies the principle of photoelectric conversion, and converts the mechanical displacement of the output shaft into pulse or digital quantity. This is the most widely used sensor at present. Because the photoelectric encoder is coaxial with the motor, when the motor rotates, the encoder (grating disc) rotates with the motor at the same speed, which reflects the speed of the current motor.

It mainly consists of 4 parts: light source, encoder, optical system and circuit. Then we will explain it according to different types of photoelectric encoders.

Incremental encoder

It converts the displacement into a periodic electrical signal, converts the electrical signal into a count pulse, and rotates the incremental encoder to output pulses during rotation, and the position is known by counting the device. And the location is number is determined by the pulse calculated from the zero mark, when after the power failure, the encoder can not have any mobile power again when encoder output pulse in the process, there can be no interference and loss of pulse, otherwise, zero memory will offset counting equipment. It is difficult to find the wrong result. If the reference point cannot be located accurately, the accuracy of location can not be guaranteed. Therefore, each operation should first refer to the reference point. But such encoders are free of blackouts and disturbances.

Incremental encoder can use the photoelectric conversion principle of A, B and Z output three square wave pulse; A and B two groups of pulse phase difference of 90 degrees, can determine the direction of rotation of the motor, and Z phase for each turn output a pulse for locating reference point. The encoder has the advantages of simple structure, mechanical average, and tens of thousands of hours of life, and has strong anti-interference ability and high reliability. However, it is unable to output the absolute position information of the axis rotation.

Two 、 absolute encoder

Each position of the absolute encoder corresponds to a definite numeric code, so its indication is only related to the beginning and termination positions of measurement, but not to the intermediate process of measurement. The location is determined by the readings of the output code. When the power is off, the absolute encoder is not separated from the actual position. The position readings are still current when the power is switched on again.

Absolute encoder can directly output a large amount of digital code, and the number of code lanes is binary digits. Each lane will be composed of light transmitting and opaque sector, and the photoelectric sensor will be used to collect the signal. A light source and a photosensitive element are respectively arranged on both sides of the code disc, so that the light sensitive element can change the level according to whether the optical signal is received or not, and output binary numbers. And output different numeric codes at different positions. Thus absolute position can be detected. But the resolution is determined by the number of bits in the binary, that is, the accuracy depends on the number of bits. Advantages: the absolute value of the angle coordinates can be read out directly, and there is no accumulated error. The location information after the power supply is removed will not be lost. The anti-interference characteristics and reliability of the data are greatly improved.

Three 、 hybrid absolute encoder

A hybrid absolute value encoder that outputs two sets of information: a set of information for detecting pole positions, an absolute information function, and the other a complete set of output information for an incremental encoder.

Four, rotating transformer

Rotating transformer is a kind of high performance silicon steel lamination and enameled wire which is specially designed by electromagnetism. Compared with photoelectric encoder, it has heat resistance and vibration resistance. Adaptability to shock, oil pollution and even corrosion resistance. A pair of extremely (single speed) rotation can be considered as a single loop absolute feedback system, and is most widely used.

Five 、 cosine servo motor encoder

Can not use high frequency communication can make the servo driver obtain high precision subdivision, thus reducing the hardware requirements, at the same time as single circle angle signal, can make the servo motor start steady, large starting torque.

In order to better test the motor performance parameters, ZLG Zhiyuan electronic MPT motor test system, the original "free load engine" technology, can be controlled response test, step response test. Able to meet the needs of the transient measurement of motors and drives, and promote the development of the industry.