| 摘要 |
PURPOSE:To reduce reactive power by performing asymmetrical control between thyristor bridges between respective phases while converting a voltage between respective phases into a sinusoidal interphase voltage. CONSTITUTION:A three-phase cycloconverter driving a tree-phase AC motor 1 is composed of antiparallel-connected thyristor bridges 2A-2B with each phase, a three-phase transformer 3 and a gate control circuit 4 asymmetrically controlling said thyristor bridges 2A-2B between respective phases. During a period of time for which a plus side voltage of one phase voltage is higher than other two phase voltages, said cycloconverter alpha-limit controls the thyristor bridge corresponding to said phase voltage, and successively switches a phase to be alpha-limit controlled at each 120 deg.. In this case, a terminal voltage to be applied to the motor 1 is given in the symmetrical waveform in spite of an interphase asymmetrical control.
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