Servo drives, also known as servo, are electrically stimulated amplifiers which used to start servo motors. Servo drives are not a new concept as they have been used for years and due to their small size they were normally been used to run radio controlled or remote controlled toy cars, robots and airplanes. Servo drives come in two types: DC and AC. Ac servo drives are built to control higher current flow such as in industrial machines, while DC servos are used for lower current flows.
The main functionality of the servo drive consists of receiving signals from the control system, analyzing the signals and at the end converting them into servo motor signals needed to produce the wanted movement. It also plays a role in monitoring any feedback signal that deviates from the set signals and adjusts the movement accordingly. The function of the servo drive described above is performed by motion control drives.
The features of a motion control drive vary per requirements of the machine in which they will be fit into. Some controllers will be built in devices that will open the circuit in case of an overload and control the movement of the torque. In some other motors, the motion controllers carry temperature sensors that break the circuit in case of high increase in temperature from the set score. Such a break in the circuit causes the motor movement to stop and then can be changed as per requirement. In more complex servo drives, motion controllers built as an integrate part of closed loop control which facilitates the accurate movement of machines. Servo motion control systems type determined as per the type of machine that it has to operate on.
In servo drives the motion controlled by three basic methods:
By pulse width modulation- this technique controls the motion of a torque based on the analysis of the feedback signal coming from the control system as to for how long the pulses will remain high. Direct torque control drive, or pulse and direct drive- these motion controllers are used to control the movement of AC motors only. The torque calculated as per the current and voltage feedback, that determines the amount of movement. In other servo drives, the motion control device counts the counter electromotive force before opening the circuit loop. The calculation based on the amount of current flowing through every coil in a motor.
Motion control drives are an important part of all electrically operated machines. They control the movement of the device and also are efficient in saving it from breakdown due to over load.