| 摘要 |
PURPOSE:To permit the starting of a motor without preparing any special circuit power source, by a method wherein the control phase angle of a power source side converter is fixed in the vicinity of 90 deg. prior to the starting of the AC motor while a motor side converter is brought into a pulse off condition. CONSTITUTION:When an operating command is given, the control phase angle of a thyristor rectifier 3 is set at 90 deg. at first. In this case, a thyristor invertor 5 is in pulse off condition, therefore, charging current is conducted through the snapper capacitor of the thyristor invertor 5 bia a thyristor rectifier 3 whereby the circuit power source of a high voltage side control circuit is established. When the starting command is outputted after establishing the circuit power source, the control phase angle of the thyristor rectifier 3 is released from the fixing at 90 deg. while the pulse off of the thyristor invertor 5 is released in synchronizing with the pulse of the thyristor rectifier 3.
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