Servo motor working principle
1, the servo system is to make the object's position, position, status, etc. output is controlled to follow the input target (or given value) of any change in the automatic control system. Servo mainly by pulse to locate, basically can be understood that the servo motor receives a pulse, it will rotate a pulse corresponding to the angle, in order to achieve displacement, because the servo motor itself has a pulse function, so each servo motor Rotating an angle will produce the corresponding number of pulses, thus forming a response with the pulse received by the servomotor, or by closing the loop so that the system knows how many pulses are sent to the servomotor and how many pulses are received at the same time In this way, it is possible to control the rotation of the motor very precisely for precise positioning, up to 0.001 mm. DC servo motor is divided into brush and brushless motor. Brushed motor low cost, simple structure, large starting torque, wide speed range, easy to control, need maintenance, but inconvenient maintenance (for carbon brush), resulting in electromagnetic interference, environmental requirements. So it can be used for cost-sensitive general industrial and commercial applications.
Brushless motor small size, light weight, large output, fast response, high speed, small inertia, smooth rotation, torque stability. Control complex, easy to achieve intelligent, the electronic commutation method is flexible, square wave commutation or sine wave commutation. Motor maintenance-free, high efficiency, low operating temperature, electromagnetic radiation is small, long life, can be used in a variety of environments.
2, AC servo motor is also a brushless motor, is divided into synchronous and asynchronous motor, the current motion control are generally used synchronous motor, its power range, you can do a lot of power. Large inertia, high maximum speed of rotation, and quickly decreases as power increases. It is suitable for low-speed smooth operation of the application.
3, the rotor inside the servo motor is a permanent magnet, the driver controls the U / V / W three-phase power to form an electromagnetic field, the rotor in the magnetic field under the action of rotation, while the motor comes encoder feedback signal to the driver, the driver feedback value Compare with the target value and adjust the angle at which the rotor rotates. The accuracy of the servo motor depends on the accuracy of the encoder (number of lines).
AC servo motor and brushless DC servo motor in the functional difference: AC servo is better because it is a sine wave control, torque ripple small. DC servo is trapezoidal wave. But the DC servo is relatively simple and cheap.