PHASE CONTROL METHOD FOR INDUCTION SERVOMOTOR Russian patent published in 2005 - IPC

FIELD: electrical engineering; variable-speed ac drives.

SUBSTANCE: proposed method includes variation of phase magnitude and polarity of voltage fundamental harmonic across control winding by means of semiconductor switching unit built around two pairs of transistor switches connected into bridge circuit; to this end each pair of transistors is alternately twice connected during supply voltage cycle at advance angles α₁ ≤ 0 during first turn-on operation and at remaining angles α₂ ≤ 0 during second turn-on period provided total modular value of these angles equals 180 el. degrees. Depending on desired sense of rotation, first or second pair of transistors is turned on at mentioned angles to ensure direct or, respectively, reverse connection of control winding; other pair of transistors is brought in conduction during moments coinciding with reversal of supply voltage polarity. Static characteristic of electric drive is linearized by means of nonlinear reverse-characteristic regulator installed at control input.

EFFECT: enhanced regulation precision and reliability for induction motors of closed-circuit computerized control systems.

2 cl, 9 dwg