| 摘要 |
PURPOSE:To obtain the voltage of the whole capacity of the converter when converting the polarity of load currents by supplying gate pulses to a thyristor driven when converting the polarity and a thyristor driven in the lag phase of 120 deg. el more than said thyristor when converting the polarity. CONSTITUTION:The gate pulses formed by a current regulator 1, a firing angle regulator 2 and a pulse shaping circuit 3 are outputted through an or circuit 10 and an circuit 5 while being outputted through an and circuit 9, each two in each group of an upper side thyristor group U, V, W and a lower side thyristor group X, Y, Z operate, and the next phase of 120 deg. el lag is driven simultaneously in such a manner that the thyristors V, Z are operated when driving the thyristors U, Y. An execution discriminating circuit 6 detects the reaching of output frequency to predetermined value or higher, and forwards signals to an and circuit 8, and a monostable multivibrator 7 receives a command from a current changeover command circuit 4, operates for a fixed time and gives the and circuit 8 signals. |
