To improve energy indicators of the thyristor drives (TD) of the mill stands the concept of two-zone variable speed control systems has been developed which is based on the principle of the rectified electromotive force store reallocation of the thyristor convertor in the steady and dynamic modes. It helps to reduce the store amount by means of its more efficient use. In the frame of the above concept the method and system of the subordinate excitation flux control in function of the rectified electromotive force (EMF) of TD have been developed. The essence of the method consists in forming the reference signal to the outer circuit controller in the exciting circuit proportionally to the rated rectified EMF. To limit the store of the rectified TD EMF at the shock loading development the method and system of the subordinate excitation flux control with automatic readjustment of the rectified EMF as well as two-zone variable speed control systems with switching the coordinate controlled according to the exciting circuit have been developed.