| 摘要 |
PURPOSE:To permit prompt regeneration of motor or reactor energy on the power source side by causing a cyclo-converter element to be fired for a short period of time only for a short period of time at the time of the switching from direct input drice to cyclo-converter variable speed drive. CONSTITUTION:A power source side commutation command isgnal generating circuit 21 and a load side commutation command signal generating circuit 22 and a switching signal generator 23 for effecting switching between derect input drive and cyclo-converter variable speed drice are connected to NAND circuits 24 to 29, through which a signal ''0'' is provided to a thyristor gate pulse amplifier 30 when the output of the circuit 22 and 23 are ''1''. Thus, when the output of the switching singla generator 23 is changed from ''0'' to ''1'', a signal ''1'' is produced for a constant period of time to forcibly lock the circuit 22 to xx ''1'' while causing a phase controller 32 to reduce the firing phase angle to the UPSILON side. In this way, switching can be effected safely and in a short period of time. |
