Model-based Speed Control of a DC Motor Using a Combined Control Scheme

The separately-excited DC motor is a high-performance variable speed drive vital for industrial applications such as robotics, actuation, control and guided manipulation because of its precision, simplicity, continuous control feature and wide speed range. Hence there is need to accurately regulate and drive the motor at desired speed. The individual armature voltage and field current methods are flawed in their inability to control the motor speed over a wider range. Hence this paper is proposing a combined armature voltage and field current control method using Internal Model Control (IMC) feedback control scheme that will ensure reference speed tracking, a fast and non-oscillatory response for the DC motor speed. The armature voltage and field current control techniques are both modelled, fully capturing the dynamic effects of the armature and field excitation of the DC motor. The derived model is then used to obtain optimal settings for a PID controller that will control the motor speed. This model-based controller enhances the performance of the motor. Computer simulations are presented to show the effectiveness of the proposed control scheme.