The paper is devoted to the substantiation of energy saving algorithms for a scalar frequency control system of a main mine fan drive. The algorithms have been based upon dependencies of energy losses on flux linkage which enabled to formulate an optimal control law. These dependencies have been derived from results of simulation on the basis of a drive model which takes into account all kinds of energy losses. Minimization of energy losses has been implemented by a gradient algorithm search method of loss function extremum. Modeling of an optimal algorithm for starting the motor has revealed reduction of energy losses and improvement of the power factor.