A passivity-based PI control design for DC-drives

In this paper, a new controller design method is developed for the control of separately excited dc motors, fed by a three phase PWM ac-dc converter. A complete model is developed using the d-q reference frame for the ac part and the conventional dc formulation for the motor. Based on passivity analysis, by using as storage function the total energy of the system, it is proven that the system is always passive independently from the way the converter is regulated. Therefore, suitable PI controllers are proposed that achieve angular speed regulation and unit power factor operation. Finally, extensive simulations verify the effectiveness of the proposed control scheme.