Abstract: The relation between the electromagnetic torque and the rotor speed of an induction motor is derived in the synchronous frame of the stator voltage. The dynamic characteristic of a vibrating system with two-motor drives rotating in opposite directions is analyzed by using the dynamic theory and the equations of frequency capture are established. The conditions for implementing frequency capture and the equations of calculating capturing frequency and the phase difference are obtained. The stable equations of implementing frequency capture in the system are deduced by using nonlinear dynamics theory and the condition for system stability is obtained by using Routh-Hurwitz criterion.

Key words: Electric-mechanic coupling, Frequency capture, Non-linear dynamics, Self-synchronization, Vibrating system