A servo motor is an electric motor that achieves precise control of position, speed, or torque through a closed-loop control system. Its core lies in real-time feedback and adjustment, which can quickly respond to instructions and achieve high-precision motion control. It is widely used in industrial automation, robotics, CNC machine tools and other fields.
1、 The core components of servo motors
Motor body
Usually used for AC synchronous motors (such as permanent magnet synchronous motors PMSM) or DC brushless motors (BLDC) to provide power output.
Encoder (sensor)
Used for real-time detection of the position, speed, and angle of motor rotors, common types include:
Incremental encoder: calculates displacement based on the number of pulses.
Absolute encoder: directly outputs absolute position information without losing data after power failure.
Servo drive (controller)
Receive instructions from the upper computer (such as PLC), combine with encoder feedback, adjust current and voltage to control the output of the motor.
Control loop
Position ring: Ensure precise arrival at the target position.
Speed loop: Adjust the stability of motor speed.
Current loop (torque loop): controls the output torque to prevent overload.
2、 Working principle of servo motor
Closed loop control process
Input command: The upper computer sends the target position/velocity signal.
Feedback comparison: The encoder sends the actual running data back to the driver.
Error correction: The driver calculates the deviation and adjusts the output until the error approaches zero.
Dynamic response characteristics
High bandwidth design, capable of accelerating, decelerating, or emergency stopping in milliseconds (such as response time<1ms).
3、 Classification of servo motors
By current type
AC servo motor: mainstream type, wide power range (50W~15kW), strong anti-interference ability.
DC servo motor: simple structure, suitable for small equipment, but requires regular replacement of carbon brushes.
By application scenario
Universal type: standard industrial scenarios (such as conveyor belts, robotic arms).
High precision type: semiconductor manufacturing, optical positioning (positioning accuracy ± 0.001mm).
Explosion proof/waterproof type: for special environments such as chemical and underwater operations.
According to mechanical structure
Rotary servo motor: commonly used in angle control.
Linear servo motor: directly outputs linear motion without the need for a transmission mechanism (such as precision machine tools).
4、 The core advantages of servo motors
High precision control
The position error can be controlled within ± 1 pulse, and the repeated positioning accuracy can reach micrometer level.
Strong dynamic performance
Overload capacity up to 300% (short-term), wide speed range (0-6000rpm or above).
Efficient and energy-saving
Only outputs power when needed, with low standby power consumption, saving 30% to 50% energy compared to traditional stepper motors.
Intelligent integration
Supports industrial bus protocols such as EtherCAT and CANopen, facilitating linkage with PLCs and HMIs.
5、 Application fields of servo motors
Industrial automation
Mechanical arm joint drive, CNC machine tool spindle control, synchronous positioning of packaging machinery.
Robotics Technology
Steering and driving of humanoid robot joints and AGV (Automated Guided Vehicle).
Precision instruments
The wire feeding and platform movement of 3D printers, as well as medical equipment such as CT scanner rotating mechanisms.
New Energy and Transportation
Electronic power steering (EPS) and wind turbine pitch control for electric vehicles.
6、 Servo motor vs stepper motor
|Features | Servo Motor | Stepper Motor|
|Control mode | Closed loop feedback (real-time error correction) | Open loop control (no feedback)|
|Accuracy | High (dependent on encoder resolution) | Medium (prone to step loss)|
|Speed and torque | High speed and high torque (strong overload capacity) | High torque at low speeds, easily attenuated at high speeds|
|Cost | High (complex system) | Low (simple structure)|
|Applicable scenarios | High dynamic, high-precision requirements | Low speed, low-cost and simple control|
7、 Mainstream servo motor brands
Japanese brand
Yaskawa: ∑ 7 series, fast response speed, suitable for high-speed production lines.
Panasonic: MINAS A6 series, small in size, suitable for compact devices.
European brand
Siemens: SINAMICS A10, integrated safety features, compliant with Industry 4.0 standards.
Schneider: Lexium 28 series, supports multi axis synchronous control.
Domestic brand
Inovance: IS620N series, with high cost-effectiveness and complete localized services.
Delta: ASDAB3 series, suitable for electronic manufacturing and logistics automation.
8、 The development trend of servo system
Integration
Integrated design of drive and motor (such as Mitsubishi's MELSERVOJ5) reduces wiring complexity.
Intelligentization
Built in AI algorithm to achieve advanced functions such as vibration suppression and temperature adaptation.
Networking
Support 5G and edge computing, and realize remote monitoring and predictive maintenance.
Miniaturization and lightweighting
Adopting new materials (such as carbon fiber shell) to enhance power density (such as ABB's MicroFlex e190).
If you need to know the selection parameters of servo motors (such as inertia matching, rigidity adjustment) or specific application cases (such as six axis robot drive scheme), you can further explore!