A servo motor is an electric motor that allows the control of acceleration, rotation speed and angular position of the motor shaft. The core, the electric motor, is equipped with a sensor. This sensor determines the position of the motor shaft. This is permanently reported to the external control electronics (servocontroller). A stepper motor can also take over the task, but has disadvantages with high loads due to the missing control loop and the missing sensors.
A servo drive consists of a servo controller and a servo motor. Operation takes place in a closed loop, which can be controlled by position, speed or torque. Nesting allows combinations. This in turn enables a wide range of applications. A servo drive can contain any type of electric motor, such as a synchronous motor.
Functionality of servo motors:
A given position setpoint is compared with the encoder signal. In the event of a deviation, the motor is rotated in the direction of the shorter travel to the setpoint. This reduces the deviation. This process is repeated until the current value is incrementally within the tolerance limits (setpoint). In addition, the speed and torque can also be controlled according to this principle. One application is uniform travel profiles for fluctuating loads.
Where does this principle apply?
This drive technology is mainly used in industrial plants, but also in packaging machines, industrial robots or machine tools. "Servos" are servo motors that are very popular in model making (ship, vehicle or aircraft models). The power density is excellent. These electric motors are therefore predestined for display devices in the military or aviation industry. Especially in aviation, the dynamics in the air are enormous. An error or an incorrect display in the millimetre range on the screen leads to a catastrophe. The CANopen fieldbus interface (communication profile DS 301) and the DSP 402 device profile are now familiar to everyone in the industry. They function as compact drives for automation. The motors are controlled by a soft PLC, which is connected downstream in the process computer. DC servo motors are equipped with Profibus DP interface (PROFIdrive profile). The low power range (40 W - 500 W) is thus covered.
What are the requirements for a good servo motor manufacturer?
Since servo motors form the heart of every industrial unit, it must always be fully functional. In this environment, therefore, great importance is attached to quality, performance and longevity. Replacement motors must be available in the event of a longer breakdown. Repair and maintenance services must be flawless, regular and quickly ready for use. In the event of an engine stoppage, the losses run into millions. No company can afford this. Responsible producers take these high requirements into account. Second motors or replacement motors are a common solution to be prepared in case of emergency.
As this also involves a high financial outlay, used or leased engines are often used. Manufacturers often offer used servo motors. These are checked and have a guarantee.