Synchronous motors and their modifications (ac converter-fed motor, etc.) enable to develop low-noise, reliable and economically efficient electric drive systems. The construction of up-to-date systems based on the synchronous machines is impossible without development of the computing software incorporating mathematical and computing simulation. In its turn, modelling of the synchronous machines as a rule is based on the equations by Park-Gorev, application of which requires adoption of a series of allowances. These allowances in a number of cases do not permit to obtain adequate results of the simulation coinciding with the results of field experiments of the systems under review. Moreover, while applying the system of equations by Park-Gorev to research the systems including interaction of synchronous machines with semiconducting converters of electric energy it is necessary simulate the process of formation their controlling signals in the sphere of frequency. If the states of converter’s keys are defined not only by controlling impulses but also by the state of currents in the synchronous machines flowing through them, such approach is not reasonable.