Historically DC drives and motors were fitted because they were the only way to accurately control motor speed. DC motors are simple to control and provided accurate and fast torque control along with high dynamic speed response.
However there are a number of drawbacks to using DC motors which include; reduced reliability due to the fact that brushes and commutators wear down and need regular servicing; a greater financial investment as DC motors can be costly to purchase along with the need for tachometers, encoders for speed and position feedback.
While a DC drive produces an easily controlled torque from zero to base speed and beyond, the motor’s mechanics are more complex and require regular maintenance.
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