Torque is directly proportional to

Torque is directly proportional to armature current in the
dc motor. By using an inner-current control loop, the dc drive
can directly control torque. Likewise, the constant magneticfield
orientation, which is achieved mechanically through
commutator action, makes direct flux control a given. Thus,
two primary factors toward insuring responsive control (i.e.,
direct torque control and direct flux control) are both present
in the dc drive. The relatively simple electronics required to
implement the dc drive represents another advantage. On the
negative side, both the initial and maintenance costs of dc
motors are high, and high performance speed accuracy can
only be achieved if an encoder is included for feedback.
armatur
directly
proportional