1. Servo motor encoder principle:
A servo motor encoder is a sensor installed on a servo motor to measure the position of the magnetic poles and the rotation angle and speed of the servo motor. Based on the different physical media, servo motor encoders can be divided into photoelectric encoders and magnetoelectric encoders. In addition, a rotary transformer is also considered a special type of servo encoder. The market mainly uses photoelectric encoders, but magnetoelectric encoders, as a rising star, have the characteristics of reliability, low price, and resistance to pollution, and are trending towards surpassing photoelectric encoders.
The basic functions of a servo encoder are the same as those of a regular encoder . For example, absolute encoders have signals such as A, A-inverse, B, B-inverse, Z, Z-inverse, etc. However, servo encoders differ from regular encoders in that most servo motors are synchronous motors. When a synchronous motor starts, the position of the rotor's magnetic poles needs to be known in order to start the servo motor with high torque. This requires several additional signals to detect the rotor's current position. For example, incremental encoders have signals such as UVW. Because of these signals for detecting the rotor position, servo encoders appear somewhat complex, making them difficult for the average person to understand. In addition, some manufacturers deliberately conceal certain signals, and related information is incomplete, further adding to the mystique surrounding servo motor encoders.
Since phases A and B are 90 degrees out of phase, the forward and reverse rotation of the encoder can be determined by comparing whether phase A or phase B comes first. The zero-position reference position of the encoder can be obtained through the zero-position pulse.
Encoder disks are made of glass, metal, or plastic. Glass disks have very thin lines deposited on glass, resulting in good thermal stability and high precision. Metal disks have lines directly engraved with both through and non-through surfaces, making them less prone to breakage. However, due to the thickness of the metal, their precision is limited, and their thermal stability is an order of magnitude worse than that of glass. Plastic disks are economical, with low cost, but their precision, thermal stability, and lifespan are all inferior.
Resolution—The number of through or dark lines provided by an encoder per 360 degrees of rotation is called resolution, also known as resolution scale or simply the number of lines. It is generally 5 to 10,000 lines per revolution.
2. How many wires does a servo motor encoder have?
For 4-wire encoders, an additional shield is required, including power supply positive and negative, DATE+, and DATE. For 8-wire encoders, an additional shield is needed, with power supply positive and negative (A+, A-, B+, B-, DATE+, DATE-) and sensor power supply positive and negative (CLOCK+, CLOCK-, DATE+, DATE-). For 12-wire encoders, with an additional shield, the wiring is as follows: power supply positive and negative, sensor power supply positive and negative (A+, A-, B+, B-, CLOCK+, CLOCK-, DATE+, DATE-). Incremental encoders have many wiring options. For 4-wire encoders with an additional shield, the power supply positive and negative is A, B+; for 5-wire encoders with an additional shield, the power supply positive and negative is A, B+, Z; for 6-wire encoders with an additional shield, the power supply positive and negative is A+, A-, B+, B-; and for 6-wire encoders with an additional shield, the power supply positive and negative is A+, A-, B+, B-. 8-lead shielded encoder: Power supply positive and negative, A+, A-, B+, B-, Z+, Z-. 10-lead shielded sine/cosine encoder: Power supply positive and negative, sensor power supply, A+, A-, B+, B-, R+, R-. 14-lead shielded sine/cosine encoder: Power supply positive and negative, sensor power supply, A+, A-, B+, B-, R+, R-, C+, C-, D+, D-. 14-lead shielded encoder: Power supply positive and negative, sensor power supply, A+, A-, B+, B-, Z+, Z-, U+, U-, V+, V-, W+W-, etc.
3. Servo motor encoder wiring diagram
