| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an inexpensive inverter capable of driving an induction motor without stopping the device at the time of instantaneous power failure without need for providing a DC voltage detector. <P>SOLUTION: A power failure detector 6 detects the instantaneous power failure of a three-phase AC power supply 1, and a switch 11 is immediately closed through a judging device 9. The voltage of an inverter unit 4 is controlled so that A power computing unit 15 obtains the power P of an induction motor (IM) 5 from the voltage of a phase voltage reference signal generator 13 and the current of IM5 detected by current detectors 14a to 14 c. A deviation detector 16 obtains a deviation ΔP between the power P and a power command value Ps (=0), and the deviation ΔP is used as a torque command T through a divider 17. An integrator 18 integrates the torque command T in consideration of inertia energy of the IM5, and the amount of frequency collection ωs is outputted to an accumulator 20 through the switch 11, and the accumulator 20 adds the amount of frequency collection ωs and a speed command ωr to obtain an output frequency command ωo, so that the voltage of an inverter unit 4 is controlled. Consequently, the IM5 is transferred to regenerative running and the DC voltage is not lowered, thus continuing to operate the induction motor 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
