US Patent No. 9,306,487

MOTOR DRIVE DEVICE HAVING FUNCTION OF DETECTING CONTACT FUSION IN ELECTROMAGNETIC CONTACTOR


Patent No. 9,306,487
Issue Date April 05, 2016
Title Motor Drive Device Having Function Of Detecting Contact Fusion In Electromagnetic Contactor
Inventorship Wataru Kuroki, Yamanashi (JP)
Assignee Fanuc Corporation, Yamanashi (JP)

Claim of US Patent No. 9,306,487

1. A motor drive device which comprises an AC/DC converter which converts an alternating current voltage which is supplied
from a three-phase alternating current power supply to a direct current voltage, a detection circuit of the input power voltage,
and a detection circuit of the input current, in which motor drive device, said AC/DC converter comprising a three-phase bridge
circuit comprised of a switching device and a diode, and said detection circuit of an input power voltage and detection circuit
of an input current having an electromagnetic contactor which turns the input power line on/off set between them, said motor
drive device provided with the following:
an off circuit of an electromagnetic contactor for turning off said electromagnetic contactor in the state charged by the
direct current voltage of said AC/DC converter;

a partial controller of the three-phase bridge circuit for turning on the upper arm of one phase of said three-phase bridge
circuit for the phase with the lowest input voltage and for turning on the lower arm of one phase of said three-phase bridge
circuit for the phase with the highest input in the state where the off circuit of said electromagnetic contactor turns off
said electromagnetic contactor;

a current detector for detecting if current is flowing or not flowing in the state where said partial controller of the three-phase
bridge circuit has turned on said upper arm of one phase and said lower arm of one phase; and

a contact fusion detector whereby said current detector detects said electromagnetic contactor is normal when not detecting
current and said current detector detects that it has a fused contact when detecting current in the state where said partial
controller of the three-phase bridge circuit turns on said upper arm of one phase and said lower arm of said one phase.