The speed regulator in the following figure uses a
PI controller. The controller outputs the armature current reference (in pu)
used by the current controller in order to obtain the electromagnetic torque
needed to reach the desired speed. During torque regulation, the speed
controller is disabled.
controller takes the speed reference (in rpm) and the rotor speed of the DC
machine as inputs. The speed reference change rate will follow user-defined
acceleration and deceleration ramps in order to avoid sudden reference changes
that could cause armature over-current and destabilize the system. The speed
measurement is filtered by a first-order low-pass filter.