How Do Encoders Work

How Do Encoders Work

During motor operation, real-time monitoring of parameters such as current, rotational speed, and relative position of the circumferential direction of the rotating shaft determines the status of the motor body and the equipment being towed, and furthermore, real-time control of the motor and the equipment's operating conditions, thus realising many specific functions such as servoing, speed regulation, and so on. Here, the application of encoder as the front-end measurement element not only greatly simplifies the measurement system, but also precise, reliable and powerful.

Encoder is a rotary sensor that converts the position and displacement of rotating parts into a series of digital pulse signals, which are collected and processed by the control system to issue a series of commands to adjust and change the operating status of the equipment. If the encoder is combined with a gear bar or screw screw, it can also be used to measure the position and displacement of linear moving parts.

Encoders are used in motor output signal feedback systems, measurement and control equipment. The encoder is internally composed of two main parts, the optical code disc and the receiver. The optical code disc rotates and the resulting optical parameters are converted into the corresponding electrical parameters, which are amplified by the preamplifier and the signal processing system in the inverter, and the output signals to drive the power devices are output.

Generally, the rotary encoder can only feed back a speed signal, compared with the set value and feedback to the inverter execution unit, so as to adjust the motor speed.

According to the detection principle, the encoder can be divided into optical, magnetic, inductive and capacitive. According to its scale method and signal output form, can be divided into incremental, absolute and hybrid three.

Incremental encoder, its position is determined by the number of pulses counted from the zero mark; it converts the displacement into a periodic electrical signal, and then converts this electrical signal into counting pulses, and the number of pulses indicates the size of the displacement; the position of the absolute encoder is determined by the readout of the output code, and the readout of the output code for each position in a circle is unique, and it will not lose the one-to-one correspondence with the actual position when the power supply is disconnected. The position of incremental encoder is determined by the output code reading. Therefore, the incremental encoder is switched on again after power failure, and the position reading is current; each position of the absolute encoder corresponds to a definite digital code, so that its indication value is only related to the starting and ending positions of the measurement, and has nothing to do with the intermediate process of the measurement.

The encoder, as an information acquisition element for the operating status of the motor, is connected to the motor by means of a mechanical mounting, which in most cases requires the addition of an encoder holder and an end connection shaft to the motor. In order to ensure the effectiveness and safety of the motor operation and the operation of the acquisition system, the coaxiality requirement of the encoder termination shaft with the spindle is key to the manufacturing process.