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Elevator speed controller responsive to power failures

  • US 6,435,312 B2
  • Filed: 02/20/2001
  • Issued: 08/20/2002
  • Est. Priority Date: 02/28/2000
  • Status: Expired due to Fees
First Claim
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1. A controller of an elevator comprising:

  • a converter for rectifying AC power from an AC power source and converting the AC power to DC power;

    an inverter for converting the DC power from said converter to AC power having a variable voltage and a variable frequency and driving an electric motor operating an elevator;

    DC buses connecting said converter to said inverter;

    a power accumulating device arranged between said DC buses and accumulating DC power from said DC buses during regenerative operation of the elevator, and supplying accumulated DC power to said DC buses during powered operation of the elevator;

    a charging-discharging control device for controlling charging and discharging of said power accumulating device with respect to said DC buses;

    power failure detecting means for detecting a power failure;

    current detecting means for detecting output current of said inverter;

    voltage detecting means for detecting output voltage of said inverter;

    car load measuring means in a car of the elevator and measuring load in the car;

    speed detecting means for detecting operating speed of the elevator; and

    speed control means for controlling operation of said inverter to control speed of the elevator based on speed commands and the speed of the elevator detected by said speed detecting means, wherein said speed control means stores a first table with power set in accordance with the speed and the car load, output power of said inverter is calculated based on current detected by said current detecting means and voltage detected by said voltage detecting means during a power failure, using said power failure detecting means;

    power required to operate the elevator is calculated from the table based on the load in the car measured by said car load measuring means and the speed detected by said speed detecting means; and

    speed commands for speed control are calculated within a range of discharging ability of said power accumulating device based on comparison of the output power of said inverter calculated, the power required, and the discharging ability of said power accumulating device.

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