Speed control of DC motor drives based on efficient utilization of energy and optimal performance

The most flexible control is obtained by means of a separately-excited DC motor, in which the armature and field circuits are provided with separate sources. The speed control in a DC motor is widely applied. The concept of control system optimization comprises a selection of a performance criterion and a design which yields the optimal control system subjective to the limits imposed by physical constraint, which will minimize some measure of deviation from ideal behaviour. In addition to considering errors as a measure of system performance, however, it must pay attention to the energy required for the control action, for efficient utilization of energy, since the control input is proportional to the required energy. If the errors are minimized regardless of the energy required, then a design may result in an overly large value of control input. The discrete optimal control theory in addition to the preview feedforward control, which depends on minimizing a selected performance index, are involved in the design of a system controller to obtain the optimal control law. Simulation results are obtained to investigate the effectiveness, the susceptibility, the feasibility and the transient response properties of the above mentioned system. An experimental set-up is built up to confirm the above obtained simulation results. A three phase six-pulse power converter is built to provide a variable DC power supply to the armature circuit, controlled either manually or automatically through an analog DC voltage applied from a microcomputer, in order to decrease power loss and improve the utilization of energy.