| 摘要 |
PCT No. PCT/SE91/00086 Sec. 371 Date Aug. 12, 1992 Sec. 102(e) Date Aug. 12, 1992 PCT Filed Aug. 2, 1991 PCT Pub. No. WO91/12656 PCT Pub. Date Aug. 22, 1991.A control system for an AC induction motor, comprising a stator, a rotor, at least two stator windings and rotor windings. The control system comprises a first vector rotator for rotating control signals with a first angle ((alpha)) for providing output signals connected to frequency inverters for providing drive signals to each stator winding of the motor, said first angle ((alpha)) being the time integral of a rotation frequency (w). Moreover, the control system comprises a second vector rotator for counterrotating measured drive voltages and/or currents with a second angle (-(alpha)) which is the inverse of said first angle ((alpha)). The rotation frequency (w) is controlled in dependence of said counterrotated measured voltages and/or currents essentially for maintaining the amplitude of said magnetizing currents (Im) of each stator winding constant which is a necessary condition for obtaining Natural Field Orientation.
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