DC drives
Introduction
DC drive system has been in use for nearly a century now, with the first drive ever to be developed being claimed to be operated on direct current. DC drive is the speed control system of the DC motors. The basic DC drive control system helps in starting, stopping, changing the direction and speed of the motor. The DC drive system which has only two main component, a converter and a regulator, is simpler is operation to the AC drive and is ideal in many operations. Another advantage is that the DC drive can be retrofitted with existing DC motors.
Speed of a DC motor is directly propotionae depends on the armature voltage and field current, the DC drives helps in controlling both the two currents. Motor Speed is primarily determined by Applied Armature Voltage.Motor Torque is controlled by Armature Current (amperes). Understanding these two concepts of DC motors provides the key to understanding total drive performance.
Types of DC drives:
There are several types of DC drives available with various speed controls. Some of them being:
Nonregenerative DC Drives - It is the most conventional type and basic type of drive that is commonly used. In the most simple form the control motor speed and the torque are in one direction. Certain additional components like the electromechanical (magnetic) armature reversing contator are provided to enhance the capability of the drive.
Regenerative DC Drives - A regenerative DC drive basically consit of two coordinated DC drives integrated within a common package. Regenerative adjustable speed drives are capable of controlling not only the speed and direction of motor rotation, but also the direction of motor torque.
Brushless DC Drives: A drive that is frequently being used, a brushless drive does not contain a brush. The motor contains permanent magnets, the size of the magnets determine the horse power capabilities of the motor. |
