The paper analyzes energy saving potentials in a mine ventilation system of high power consumption in order to substantiate multipurpose control system for a main fan adjustable speed drive to minimize energy losses at different cross-sections of an energy flow. Modes of mine fans at minimum energy losses due to frequency control application have been derived on the basis of modeling of fan operational characteristics and variation of equivalent ventilation system resistance during the life time of a ventilator. An iterative search method for choosing the optimal parameters of complex axial fan control has been proposed to achieve maximum available efficiency at the specific mode of fan operation.