| 摘要 |
PROBLEM TO BE SOLVED: To detect overvoltage of an AC power supply even if an overvoltage detection circuit is connected closer to a motor side than an AC reactor.SOLUTION: An overvoltage detection area discrimination circuit 162 outputs a signal for stopping detection of overvoltage of an AC power supply 200 while a power running regenerative mode detection circuit 160 detects a regenerative mode and until prescribed time elapses after detecting transition from the regenerative mode to a power running mode, and outputs a signal for detecting overvoltage while the power running regenerative mode detection circuit detects the power running mode. A reference value comparison circuit 164 compares a power supply voltage estimation value obtained by multiplying a DC average current calculated by an averaging circuit 144 by a constant number R, correcting voltage drop of an AC reactor 125, and estimating power supply voltage, with reference voltage, and determines overvoltage and outputs an overvoltage detection signal if the power supply voltage estimation value is larger than the reference voltage when the signal for detecting overvoltage is output from the overvoltage detection area discrimination circuit 162. |
