Elevator speed controller responsive to dual electrical power sources

• US 6,422,351 B2
• Filed: 02/20/2001
• Issued: 07/23/2002
• Est. Priority Date: 02/28/2000
• Status: Expired due to Fees

• Current Assignee: Korea Electric Power Corporation (Government of South Korea), Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Korea Electric Power Corporation (Government of South Korea), Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kobayashi, Kazuyuki, Araki, Hiroshi, Suga, Ikuro, Tajima, Shinobu
• Primary Examiner(s): SALATA, ANTHONY J
• Application Number:
  US09/785,465
• Publication Number:
  US 20010017239A1
• Time in Patent Office: 518 Days
• Field of Search: 187/290, 187/296, 187/297, 187/247, 318/375, 318/376, 318/758-816, 307/64, 307/66
• US Class Current: 187/290
• CPC Class Codes: B66B 1/285 with the use of a speed pattern generator
• CPC Class Codes: B66B 1/30 effective on driving gear , e.g. acting on power electronics, on inverter or rectifier controlled motor
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence

Abstract

An elevator controller providing stable speed control using a cheap power accumulating device having a low capacity even in discharging. The controller has a converter, an inverter, a power accumulating device arranged between DC buses, a charging-discharging control circuit for controlling charging and discharging of the power accumulating device, a power failure detector, a current measuring instrument and a voltage measuring instrument for respectively detecting an output current and an output voltage of the inverter, a car load measuring instrument, an encoder, and a speed control circuit for controlling the inverter. The speed control circuit calculates output power of the inverter, and calculates discharging power of the power accumulating device on the basis of a measured value of charging and discharging states. The speed control circuit calculates a maximum power as a sum of the discharging ability power and power of an AC power source, and changes speed commands on the basis of comparison of the output power of the inverter and the maximum power.

Claims

1. An elevator speed controller responsive to dual electrical power sources, the speed controller comprising:

a converter for rectifying AC power from an AC power source to produce DC power, the AC power source supplying AC power only up to a power limit;

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

DC buses connecting said converter to said inverter;

a power accumulating device connected said DC buses, charging by accumulating DC power from the DC buses during a regenerative power operation of the elevator, and discharging by supplying the accumulated DC power to the DC buses during 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;

charging-discharging state measuring means for measuring at least one of temperature, charging and discharging currents, and charging and discharging voltages of said power accumulating device;

current detecting means for detecting an output current of said inverter;

voltage detecting means for detecting an output voltage of said inverter;

speed detecting means for detecting speed of the elevator; and

speed control means for controlling operation of said inverter to control the speed of the elevator, based on speed commands of the elevator and the speed detected by said speed detecting means, said speed control means

calculating output power of said inverter based on the output current detected by said current detecting means and the output voltage detected by said voltage detecting means,

calculating discharging ability of said power accumulating device based on a value measured by said charging-discharging state measuring means,

calculating a maximum power limit as a sum of the discharge ability of the power accumulating device and the power limit of the AC power source, and

changing speed commands if the AC power output of said inverter exceeds the maximum power limit.

2. The elevator speed controller according to claim 1, wherein said speed control means includes a memory storing a table including a limited discharging current set with respect to a discharging current and a discharging voltage, calculates the limited discharging current from the table on the discharging current and the discharging voltage measured by said charging-discharging state measuring means, and calculates the discharging ability of said power accumulating device from the limited discharging current calculated and the discharging voltage measured.

3. The elevator speed controller according to claim 1, wherein said speed control means includes a memory for storing a table including a limited discharging current set with respect to a charging degree obtained by normalizing and accumulating a product of a charging-discharging current and a charging-discharging voltage, with discharging ability of power accumulating device when fully charged set as 100%, wherein

the limited discharging current is calculated from the table based on the charging degree, the discharging current and the discharging voltage measured by said charging-discharging state measuring means, and

the discharging ability of said power accumulating device is calculated from the limited discharging current calculated and the discharging voltage measured.

4. The elevator speed controller according to claim 3, wherein said speed control means includes plural tables according to the temperature of said power accumulating device, and selects a table according to the temperature measured by said charging-discharging state measuring means.

5. The elevator speed controller according to claim 1, including car load measuring means for measuring the load in the elevator, and wherein said speed control means includes a table having a speed pattern set according to the load, and calculates the speed pattern from the table based on the load measured by said car load measuring means, and generates speed commands according to the speed pattern calculated, when, based on a measured value provided by said charging-discharging state measuring means, said power accumulating device fails.

6. The elevator speed controller according to claim 1, including car load measuring means for measuring the load in the elevator, and wherein said speed control means includes a table with a maximum speed command set with respect to the load of the elevator and the discharging ability of said power accumulating device, and calculates the discharging ability of said power accumulating device based on a measured value produced by said charging-discharging state measuring means, and calculates maximum speed commands from the table based on the load measured by said car load measuring means and the discharging ability calculated, and changes speed commands based on comparison of the speed commands and the maximum speed commands.

7. The elevator speed controller according to claim 5, wherein said speed control means has plural speed pattern tables corresponding to car loads and the discharging ability of said power accumulating device, and calculates the discharging ability of said power accumulating device based on a measured value provided by said charging-discharging state measuring means, and selects a speed pattern from the tables, based on the load measured by said car load measuring means, and controls speed according to the speed pattern selected.