Servo Drives Motion Control
Brushless servo drives differ from their brushed counterparts in the mechanism of creating movement in the torque. It is a known fact that servo motors create motion on the basis of opposite forces of magnetism. To further simplify the concept of opposite magnetic forces, one can imagine a motor with a fixed magnet and a magnet that is rotating on the opposite side. While the position of the fixed magnet can not be changed the position of the other magnet can be changed or we can control the movement of the rotating magnet. This can be done by bringing a change in its polarity by altering the direction of the current by the movement of the rotating magnet. This basic process of commutating of electric current to the motor is where the principal difference between a brushless and a brushed servo drive lies.
燭he mechanism of a brushed servo drive-
A brushed servo drive has two main components-
1. Field magnets contained in a unit.
2. An iron core with coils of wire wounded around its slots and that acts as a rotor. The iron core remains connected to a commutator.
Mechanical brushes are used to direct the flow of the electric current towards the motor windings. These brushes remain in contact with the rotating magnet and caries the current to the coil that is wounded around the iron core. Since the brushed servo drive commutates the direction of the electric current flowing in to the motor therefore a brushed servo motor can use a DC electric source to create movement of the torque.
?B>Brushless servo drives on the other hand have a separate mechanism of commutation of the current to the motor windings. In these servo drives the basic construction of the central iron core is just opposite as that of a brushed servo drive. Here while the permanent magnet is the rotor, the field magnets are the stator that remains fixed in position. Now every time the current flows through the external circuit of the motor, it gets reversed at definite positions of the rotor magnet. As a result unlike brushed servo drives, the brushless servo drives are driven by alternating currents. Because of the absence of mechanical brushes in these servos drives the chances of the brush wearing out and inducing friction in to the system is remote. This is the reason why brushless servo drives are preferred over their brushed counterparts.
Read more about CNC servo drives.
Article Tags:
Brushless Servo Drives, Brushed Servo Drive, Difference Between, Brushless Servo, Servo Drives, Brushed Servo, Rotating Magnet, Electric Current, Servo Drive, Iron Core
