Source：Shengda Yu Published：2020-10-30 Clicks：10830
Servo motor refers to the engine that controls the operation of mechanical components in the servo system, and it is a kind of indirect transmission device of auxiliary motor. Servo motor is an electro-mechanical converter that can rotate continuously. The function of servo motor in servo motor maintenance is that servo motor can make control speed and position accuracy very accurate.
Servo motor can be divided into AC servo motor and DC servo motor.
The output speed of the DC servo motor is proportional to the input voltage, and the forward and reverse speed control can be realized. It has the advantages of large starting torque, wide speed regulation range, good linearity of mechanical and adjusting characteristics, convenient control and so on, but the wear and sparks of the reversing brush will affect its service life. In recent years, brushless DC servo motor avoids brush friction and commutation interference, so it has the advantages of high sensitivity, small dead zone, low noise, long life and little interference to the surrounding electronic equipment.
The transfer function of the output speed / input voltage of the DC servo motor can be approximately regarded as the first-order late link, and its electromechanical time constant is generally between ten milliseconds to dozens of milliseconds. However, the time constants of some low inertia DC servo motors are only a few milliseconds to twenty milliseconds. The rated speed of DC servo motor with low power specification is above 3000r/min, even greater than 10000r/min. Therefore, the controller as a hydraulic valve needs to be equipped with a high-speed ratio reducer. The DC torque servo motor can work at a low speed of tens of rpm, or even under the condition of blocking for a long time, so it can directly drive the control without deceleration.
DC servo motor is divided into brushless motor and brushless motor. The brush motor has the advantages of low cost, simple structure, large starting torque, wide speed regulation range, easy control and maintenance, but it is very convenient to maintain and replace the carbon brush, resulting in electromagnetic interference and environmental requirements. Therefore, it can be used in ordinary industrial and civilian situations which are sensitive to cost. The brushless motor has the advantages of small size, light weight, large output, fast response, high speed, small inertia, smooth rotation and stable torque. The control is complex, it is easy to realize intelligence, and its electronic commutation mode is flexible, which can be square wave commutation or sine wave commutation. The motor is maintenance-free, high efficiency, low operating temperature, low electromagnetic radiation, long life, and can be used in various environments.
Ac servo motor is also a brushless motor, which is divided into synchronous motor and asynchronous motor. At present, synchronous motor is generally used in motion control, which has a large power range and can achieve large power. With large inertia, the maximum rotation speed is low, and decreases rapidly with the increase of power. Therefore, it is suitable for the application of low speed and smooth operation.