Combined feedforward and feedback control of the field in a DC motor drive

For a microprocessor implemented drive control for separately excited DC motors the principle and the realization of a speed dependent field current anticipatory control are treated. The control system of the field coil is realized by a cascade control of a field current controller (performed by a combination of a precontroller with a feedback controller to cancel the error of the anticipatory control) and a superimposed EMF controller which consists also of a combination of a feedforward and a feedback-controller. By this structure very good results can be achieved. The automatic acquisition of the anticipatory characteristic, the added induced voltage controller and the field current controller are discussed. Finally structural diagrams of the field control of a realized (and industrially produced with great success) converter are shown