METHOD AND DEVICE FOR CONTROLLING SLIP-RING INDUCTION MOTOR Russian patent published in 2007 - IPC H02P25/26 

FIELD: electrical engineering; alternating-current drives for load-lifting and traveling cranes.

SUBSTANCE: proposed method and device for controlling slip-ring induction motor designed for use in load-lifting and traveling crane drives operating at reduced (creeping) speeds are characterized in that turn-on moment of thyristors or triacs is determined by comparing desired and reference voltages and thyristors or triacs are turned on at moments found in this way. Turn-on moment is determined for each thyristor of triac irrespective of other ones. Separate reference voltage is obtained from actual voltages across power circuit by summing them up. Introduced in rotor circuit of slip-ring induction motor are impedance units whose outputs are closed through thyristors or triacs in delta, transformers with secondary windings, thyristor or triac comparison and control units, feedback shaping unit, positive voltage separating units, sawtooth voltage generating units, adders, and setting unit.

EFFECT: ability of attaining parametric speed regulation effect at limited torque fluctuations.

2 cl, 3 dwg