| 摘要 |
<p>PURPOSE:To effectively protect a main motor and a chopper by outputting a command for turning OFF a brake main circuit when detecting the commutation failure of the chopper and turning OFF a self-extinguishing semiconductor element. CONSTITUTION:If a chopper 7 fails to communicate when a semiconductor element 20 is turned ON to shorten a brake series resistor 15 to perform a regenerative brake control, a commutation failure detector 19 excites a high speed trip coil 13, applies a signal to an OFF gate current forming circuit 21 to turn OFF the element 20. The resistor 15 is inserted in series with an armatur 11 simultaneously hen detecting the commutation failure, a defective current rising in a loop of the armature 11, a field winding 10, a main smoothing reactor 9, a switch 8, a chopper 7 and a high speed current reducing unit 12 in a self-exciting manner is suppressed, the breaking duty of the curent reducing unit 12 is alleviated, thereby suppressing the peak of the defective current.</p> |
