| 摘要 |
PURPOSE:To prevent the disorder of the rotation of the gate pulses, and to obviate commutation failure by forming pulses having 240 deg. width from comparison output between phase control signals and synchronous signals at once. CONSTITUTION:The comparison output between the phase control signals PC and the signals SY synchronizing with a three-phase AC power supply is shaped through pulse generating means 1, 3, and the pulses A1, B1, C1, which mutually have phase difference at every 60 deg. el at the time of regularity in 240 deg. el (an electrical angle) width, are generated. The pulses are supplied to logical circuits 4, and pulses A2, B2, C2, which mutually have phase difference at every 60 deg. el at the time of regularity in 120 deg. width, are generated, thus controlling the ignition of thyristors corresponding to each pulse. Accordingly, since the pulses having 240 deg. width are formed and the gate pulses having 120 deg. width are shaped by logically operating the pulses, the rotation of the gate pulses does not get out of order, thus preventing commutation failure. |
