As a core component of some automated equipment, the reliability and stability of motion control systems directly affect the performance of the equipment. One of the main factors affecting its reliability and stability is interference. Therefore, how to effectively solve interference problems is an issue that cannot be ignored in the design of motion control systems. I. Interference Phenomena In applications, the following main interference phenomena are often encountered: 1. The motor rotates irregularly when the control system does not issue a command. 2. When the servo motor stops moving, the value fed back by the photoelectric encoder at the motor end jumps erratically when the motion controller reads the motor position. 3. When the servo motor is running, the encoder value read does not match the issued command value, and the error value is random and irregular. 4. When the servo motor is running, the difference between the encoder value read and the issued command value is a stable value or changes periodically. 5. Equipment sharing the same power supply as the AC servo system (such as displays) malfunctions. II. Interference Source Analysis Interference enters the motion control system mainly through two channels: 1. Signal transmission channel interference: interference enters through the signal input and output channels connected to the system. 2. Power supply system interference. The signal transmission channel is the path through which the control system or driver receives feedback signals and sends control signals. Because pulse waves will experience delay, distortion, attenuation and channel interference on the transmission line, interference on long lines is the main factor during transmission. Any power supply and transmission line has internal resistance, and it is these internal resistances that cause noise interference from the power supply. If there were no internal resistance, all kinds of noise would be absorbed by the power supply short circuit, and no interference voltage would be established in the line. In addition, the AC servo system driver itself is also a strong source of interference, and it can interfere with other devices through the power supply. III. Anti-interference measures 1. Anti-interference design of the power supply system (1) Implement power supply grouping, for example, separate the drive power supply of the actuator motor from the control power supply to prevent interference between devices. (2) Using noise filters can also effectively suppress the interference of the AC servo driver to other devices. This measure can effectively suppress the above-mentioned interference phenomena. (3) An isolation transformer is used. Considering that high-frequency noise is mainly coupled through the primary and secondary coils not by mutual inductance coupling, but by parasitic capacitance coupling, the primary and secondary windings of the isolation transformer are isolated by a shielding layer to reduce its distributed capacitance and improve the anti-common-mode interference capability. 2. Anti-interference design of signal transmission channel (1) Optocoupler isolation measures In the long-distance transmission process, an optocoupler is used to cut off the connection between the control system and the input channel, output channel and the input and output channels of the servo driver. If optocoupler isolation is not used in the circuit, external spike interference signals will enter the system or directly enter the servo drive device, producing the first type of interference phenomenon. The main advantage of optocoupler is that it can effectively suppress spike pulses and various noise interferences, thereby greatly improving the signal-to-noise ratio in the signal transmission process. The main reason is that although the interference noise has a large voltage amplitude, its energy is small and it can only form a weak current. The light-emitting diode in the input part of the optocoupler works in the current state, and the conduction current is generally 10-15mA. Therefore, even if there is a high amplitude interference, it will be suppressed because it cannot provide enough current. (2) Long-distance transmission of twisted-pair shielded cables: Signals are affected by interference factors such as electric field, magnetic field and ground impedance during transmission. Using grounded shielded cables can reduce electric field interference. Compared with coaxial cables, twisted-pair cables have a lower bandwidth but higher wave impedance and stronger common-mode noise immunity, which can cancel out electromagnetic induction interference in each small link. In addition, differential signal transmission is generally used in long-distance transmission to improve anti-interference performance. Using twisted-pair shielded cables for long-distance transmission can effectively suppress the generation of the second, third and fourth interference phenomena. (3) Grounding: Grounding can eliminate the noise voltage generated when current flows through the ground wire. In addition to connecting the servo system to the earth, the signal shielding wire should also be grounded to prevent electrostatic induction and electromagnetic interference. If the grounding is not correct, the second type of interference phenomenon may occur.