1, servo system (servo mechanism) is an automatic control system that enables the object’s position, orientation, state and other output controlled quantity to follow any change of the input target (or given value). The servo mainly depends on the pulse to position, basically can be understood in this way, the servo motor receives a pulse, it will rotate the corresponding Angle of a pulse, so as to achieve displacement, because the servo motor itself has the function of pulse, so each rotation Angle of the servo motor, will emit the corresponding number of pulses, so that the pulse accepted by the servo motor echoes. Or closed loop, so that the system will know how many pulses are sent to the servo motor, and how many pulses are received back, so that the rotation of the motor can be controlled very accurately, so as to achieve accurate positioning, which can reach 0.001mm. Dc servo motors are divided into brushed and brushless motors. Brush motor has low cost, simple structure, large starting torque, wide speed regulation range, easy control, and needs maintenance, but the maintenance is not convenient (change the carbon brush), electromagnetic interference, and the environment is required. Therefore, it can be used in cost-sensitive general industrial and civil applications.
Brushless motor small size, light weight, large output, fast response, high speed, small inertia, smooth rotation, torque stability. The control is complex, easy to achieve intelligence, its electronic commutation mode is flexible, can be square wave commutation or sine wave commutation. The motor is maintenance-free, high efficiency, low operating temperature, small electromagnetic radiation, long life, and can be used in a variety of environments.
2, AC servo motor is also a brushless motor, divided into synchronous and asynchronous motors, motion control is generally used synchronous motor, its power range is large, can achieve a lot of power. Large inertia, low maximum rotational speed, and rapidly reduced with the increase of power. Therefore, it is suitable for low speed and smooth operation applications.
3, the rotor inside the servo motor is a permanent magnet, the driver control of U/V/W three-phase electric electromagnetic field, the rotor rotates under the action of this magnetic field, while the motor comes with the encoder feedback signal to the driver, the driver according to the feedback value and the target value to compare, adjust the rotor rotation Angle. The accuracy of the servo motor is determined by the accuracy of the encoder (number of lines).
The difference between AC servo motor and brushless DC servo motor in function: AC servo is better, because it is sine wave control and torque ripple is small. Dc servo is trapezoidal wave. But DC servo is simpler and cheaper.