| 摘要 |
PURPOSE:To improve the operating reliability and safety of a facility by controlling an induction motor by remaining 2-phase converters when the converter of any phase becomes defective. CONSTITUTION:Converters 6, 7, 8 capable of controlling 3-phase windings 2, 3, 4 of an AC motor 1 are independently provided. For example, when a V-phase converter 6 becomes defective to flow an overcurrent, it is detected by a U- phase defect detector 26. Then, the output signal of the detector 26 is applied to a U-phase controller 12 to all turns OFF the firing signals of thyristors of U-phase converter. Simultaneously, the output signal of the detector 26 is applied to a current reference circuit 21 to delay the phase of the V-phase current reference by 30 deg., and the amplitude is increased to 3<1/2> times. Simultaneously, the phase of the W-phase current reference is led by 30 deg., and the amplitude is increased to 3<1/2> times. The motor is controlled continuously by the excitations of V- and W-phases. |
