| 摘要 |
PROBLEM TO BE SOLVED: To reduce leakage current flowing into the ground 12 from a motor 10, attributable to the high-speed switching of the switching element 8 in the inverter 7 of a power converter 3. SOLUTION: A leakage current reducing device for an elevator includes a common mode current extraction circuit 14 for extracting a common mode current in a power line 9 from an inverter 7 to the motor 10, an interphase capacitor 15 and a common mode choke coil 17. The device detects an increase in leakage current by an increase in the common mode current and automatically perform various countermeasures such as prolonging a waiting time on each stage of a car of the elevator, reducing the switching frequency of the inverter, revising the modulation mode of PWM control of the inverter to a three-phase modulation mode, and achieving lower voltage and lower frequency of the AC power to be supplied to the motor. COPYRIGHT: (C)2009,JPO&INPIT
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