VARIABLE SPEED DRIVE DEVICE OF INDUCTION MOTOR FOR JET FAN FOR ROAD TUNNEL DRIVEN THROUGH LONG CABLE

摘要

PROBLEM TO BE SOLVED: To eliminate the deterioration of the insulation of a motor due to the switching surge of an inverter, the problem of the EMI (Electromagnetic Interference) of high-frequency band, and the erroneous operation of a leakage breaker due to the stray capacitance of a long cable and a same phase current flowing between the leakage breaker and a ground which may occur when a jet fan is driven through the long cable.;SOLUTION: A power supply input is converted from an alternating current into a direct current by an AC/DC converter 131, and the direct current is converted into the three-phase alternating current with a variable frequency and a variable voltage by an inverter circuit 132. A same phase reactor 140 and an alternating current reactor 151 are provided in series to the three-phase output terminal thereof. A star-connected first capacitor circuit 152 is connected in parallel with the rear of the alternating current reactor 151, and the terminal voltage thereof is supplied to the jet fan 400 through the long cable 300. The mid-point of the start connection of the first capacitor circuit 152 is connected to the neutral point of the AC/DC converter 131, and the same phase components of the AC/DC converter 131 and the same phase components of the inverter circuit 132 are recirculated to reduce the same phase voltage.;COPYRIGHT: (C)2012,JPO&INPIT