Definition and Basic Principles
An AC servo motor is a type of motor that can convert the input AC electrical signal into a rotational motion output with precise control over position, speed, and acceleration. Its core lies in the closed-loop control system, which typically consists of three parts: the motor body, the encoder, and the controller. By changing the magnitude and direction of the input voltage, the speed and rotation direction of the motor can be precisely controlled, enabling the precise adjustment of parameters such as position, speed, and acceleration.
The structure of an AC servo motor can mainly be divided into two parts: the stator and the rotor. There are two windings on the stator with a mutual angular displacement of 90°. One is the excitation winding, and the other is the control winding. When an AC servo motor is in use, a constant excitation voltage Uf is applied across the two ends of the excitation winding, and a control voltage Uk is applied across the two ends of the control winding. The currents passing through the excitation winding and the control winding generate a rotating magnetic field inside the motor. The direction of the rotating magnetic field determines the rotation direction of the motor. When the voltage applied to any one of the windings is reversed, the direction of the rotating magnetic field changes, and so does the direction of the motor. In order to form a circular rotating magnetic field inside the motor, a phase difference of 90 degrees should exist between the excitation voltage Uf and the control voltage UK. Commonly used methods include using any line voltage of a three-phase power supply or adopting a phase-shifting network.
Characteristics
High-precision control: The AC servo motor can achieve minute position adjustment and high-precision control, making it suitable for various occasions that require precise control.
Fast response: It has a relatively fast dynamic response speed and can quickly follow the command signal, enabling a rapid transition from rest to motion.
High reliability: It operates stably and has good controllability, and can maintain high performance in harsh environments.
Multiple control modes: It supports three mainstream control modes, namely position (pulse), speed, and torque, to meet the requirements of different application scenarios.
Strong adaptability: Different types such as the optional inner rotor motor and outer rotor motor are suitable for a variety of application scenarios such as high-speed and low-speed high-torque situations.
Application Fields
AC servo motors are widely used in numerous fields. Wherever there are relatively high requirements for the control accuracy of position, speed, and torque, AC servo drives can be adopted. Examples include machine tools, printing equipment, packaging equipment, textile equipment, laser processing equipment, robots, electronics, pharmaceuticals, financial machines, automated production lines, etc. Since servos are mostly used in positioning and speed control scenarios, servos are also known as motion control.
Advantages and Disadvantages
Advantages:
No brushes and commutators: Therefore, it has reliable operation and low requirements for maintenance and upkeep.
Small moment of inertia: It is easy to improve the rapidity of the system.
High precision: The precision of an AC servo motor depends on the precision of the motor encoder.
Good torque-frequency characteristics: It provides a constant torque output within its rated speed range and a constant power output above the rated speed.
Strong overload capacity: It has a strong overload capacity and can be used to overcome the inertial torque of the inertial load at the moment of starting.
Smooth operation: Even at low speeds, there will be no vibration phenomenon.
Disadvantages:
Higher cost: With high technological content, high-precision encoders, advanced drivers, and complex control systems are all expensive.
Relatively large energy consumption: Due to the need to ensure high precision and high response performance, the motor consumes more electrical energy during operation.
Conclusion
With its characteristics such as high precision, fast response, and high reliability, the AC servo motor plays a crucial role in numerous fields. Whether it is the precise operation on industrial automation production lines, the accurate control in medical equipment, or the high-performance requirements in the aerospace field, the AC servo motor can provide stable and precise power support. With the continuous progress of technology, the AC servo motor will demonstrate its unique advantages in more fields and promote the technological development and innovation of various industries.