| 摘要 |
PURPOSE:To prevent an unstable phenomenon based on a current intermittent phenomenon in the case when the driving currents of the polyphase motor driven through frequency converters lower by a method wherein fixed zero-phase currents are stacked when the driving currents of the motor lowers, and the drive of the motor is controlled. CONSTITUTION:Three-phase AC are applied to a three-phases AC motor 1 through transformers 13-15 and cycloconverters 2-4. Current instruction generators 6-8 and a zero-phase current instruction generator 9 are formed in order to obtain signals for controlling the cycloconverters 2-4, addition is each conducted by means of adders 10-12, and new instruction signals JR*-JT* are gained. Since zero-phase currents are equally contained in the new instruction signals and an intermittent phenomenon of currents is not generated even when an amplitude level of each phase current lowers, the motor can stably be controlled. |
