| 摘要 |
PURPOSE:To smoothly perform the torque-directional switching of a thyristor converter by eliminating a sudden change in current, by providing a delay operating circuit in an electric current polarity discriminating circuit to adjust the timing of phase reduction, in switching the thyristor converter. CONSTITUTION:In a thyrister Leonard device of a noncirculating current system, a delay circuit 15 is interposed btween the output of a current-polarity discriminating circuit 9 and a selecting circuit 11 for a thyristor converter. The polarity of a reference current 1a is inverted and a current 8a proportional to the current of the armature of a motor 3 is reduced following up the current 1a, so that even when a zero-current detecting circuit 10 operates, phase reduction is not performed. The phase reduction is performed the delay time T2 of the circuit 15 after a current-polarity discriminating signal 9a changes. When the time T2 is so set that when the armature current is almost zero, the phase reduction is performed, the switching of converters is performed without causing a sudden change in current, thereby obtaining the comfortable ride of, e.g., an elevator with less torque variation. |
