US Patent No. 9,118,270

MOTOR CONTROL DEVICE INCLUDING ELECTRIC STORAGE DEVICE AND RESISTANCE DISCHARGE DEVICE


Patent No. 9,118,270
Issue Date August 25, 2015
Title Motor Control Device Including Electric Storage Device And Resistance Discharge Device
Inventorship Masakazu Niwa, Yamanashi (JP)
Kenta Yamamoto, Yamanashi (JP)
Assignee Fanuc Corporation, Yamanashi (JP)

Claim of US Patent No. 9,118,270

1. A motor control device comprising:
a rectifier that rectifies AC power supplied from an AC side to output DC power;
an inverter that is connected to a DC link at a DC side of the rectifier, and performs interconversion of electric power between
DC power at the DC link and drive power for a motor or regenerative electric power, which are AC power;

a voltage detecting unit that detects a DC voltage value at the DC link; a power failure detecting unit that detects power
failure at the AC side of the rectifier and detects the DC voltage value;

a discharging operation determining unit that does not output a discharging start command for operating the discharging unit
during a period from the time after the power failure detecting unit detects power failure to the time that a DC voltage value
detected by the voltage detecting unit becomes equal to or lower than a first threshold, and that outputs the discharging
start command for operating the discharging unit when a DC voltage value detected by the voltage detecting unit becomes equal
to or lower than the first threshold in response to the power failure detecting unit, wherein the first threshold is set to
be equal to or lower than a crest value of an input voltage at the AC side of the rectifier;

an electric storage device that is connected to the DC link, and stores DC power;
a charging unit that has a boosting function of charging the electric storage device at a voltage higher than a DC voltage
at the DC link;

a discharging unit that makes short-circuiting between the electric storage device and the DC link to discharge DC power stored
in the electric storage device to the DC link; and

a resistance discharge device that is connected to the DC link wherein after the power failure detecting unit detects power
failure, the resistance discharge device starts resistance discharging operation of consuming DC power of the DC link by resistance
discharging when a DC voltage value detected by the voltage detecting unit is equal to or higher than a resistance discharging
start level, and the resistance discharge device stops the resistance discharging operation when the DC voltage value detected
by the voltage detecting unit is equal to or lower than a resistance discharging stop level lower than the resistance discharging
start level.