Power failure detection device null of alternating current

摘要

PURPOSE:To stop operation quickly upon power interruption regardless of the high frequency level during normal control by detecting power interruption based on a fact that the incremental variation rate of specific high frequency component exceeds a specific power interruption detection set value. CONSTITUTION:Output from a bandpass filter circuit 9 fluctuates constantly according to the state of feeder circuit for a PWM converter during normal control, e.g. the impedance of substation or the distance between the substation and an AC electric motor car. The output level is detected by a circuit 13 for detecting the variation rate which increases abruptly upon power interruption and when the output level exceeds a higher harmonic variation rate power interruption detection set value being set by a power interruption detection set value setting circuit 10A, a comparator 11 functions to output a power interruption detection signal 12 thus stopping the operation of the PWM converter 4 and a VVVF inverter 6. According to the constitution, power supply to other powering vehicle or a fault point is interrupted quickly at the time of regeneration.