A method for determining the optimal DC machine excitation for loss minimization is presented. The proposed method may be implemented by using either analog or digital techniques. The method is simple, and its implementation does not affect significantly the cost, the complexity, and the dynamics of the DC drive. Thus, energy can be saved without sacrificing the quality of the DC drive. Even though the conception of the proposed method is based on the loss model of the DC machine, it is shown that its realization does not require knowledge of the loss model. >