Servo Motor Working Principle
A servo system is an automatic control system that allows the controlled variables such as position, orientation, and state of an object to follow any change in the input target (or setpoint). Servo systems primarily rely on pulses for positioning. Essentially, when a servo motor receives a pulse, it rotates by the angle corresponding to that pulse, thereby achieving displacement. Since servo motors have the capability to generate pulses, every rotation of the motor emits a corresponding number of pulses. This creates a feedback loop or closed loop, enabling the system to know how many pulses were sent to the servo motor and how many were received back. As a result, the motor's rotation can be precisely controlled, achieving positioning accuracy up to 0.001mm. DC servo motors are divided into brushed and brushless types. Brushed motors are cost-effective, have a simple structure, high starting torque, wide speed control range, and are easy to control, but require maintenance, which is not convenient (replacing carbon brushes), and can cause electromagnetic interference, requiring specific environmental conditions. Therefore, they are suitable for cost-sensitive industrial and consumer applications.
The brushless motor is compact, lightweight, high in output, quick in response, and features high speed, low inertia, smooth rotation, and stable torque. It is complex to control but easy to implement intelligence. The electronic commutation method is flexible, allowing for either square wave or sine wave commutation. The motor requires no maintenance, is highly efficient, operates at low temperatures, emits minimal electromagnetic radiation, has a long lifespan, and is suitable for various environments.
2. Servo motors for communication are also brushless, categorized into synchronous and asynchronous types. Currently, synchronous motors are generally used in motion control due to their wide power range and ability to achieve high power levels. They have high inertia, low rotational speed, and this speed decreases rapidly as the power increases. Therefore, they are suitable for applications requiring low-speed, stable operation.
The rotor inside the servo motor is a permanent magnet. The driver controls the U/V/W three-phase electricity to form an electromagnetic field, causing the rotor to rotate under the influence of this field. Simultaneously, the motor's built-in encoder sends feedback signals to the driver, which compares the feedback value with the target value and adjusts the angle of the rotor's rotation. The precision of the servo motor depends on the precision of the encoder (lines).
The functional differences between AC servo motors and brushless DC servo motors: AC servo motors are superior due to their sine wave control and smaller torque pulsation. DC servo motors operate with a trapezoidal wave. However, DC servo motors are simpler and more affordable.
Above is the introduction to the working principle of servo motors. If you have any further questions, feel free to consult our website, where our technical staff will explain them to you.
