Elevator system using a supercapacitor as a backup power source

• US 7,331,426 B2
• Filed: 12/26/2006
• Issued: 02/19/2008
• Est. Priority Date: 07/12/2004
• Status: Active Grant

• Current Assignee: Kone Corporation
• Original Assignee: Kone Corporation
• Inventors: Jahkonen, Pekka
• Primary Examiner(s): SALATA, ANTHONY J
• Application Number:
  US11/645,052
• Publication Number:
  US 20070163844A1
• Time in Patent Office: 420 Days
• Field of Search: 187/290, 187/296, 187/297, 187/293, 307/66, 307/69, 318/375, 318/376, 318/377, 318/106, 318/108, 318/109, 318/382, 318/161
• US Class Current: 187/290
• CPC Class Codes: B66B 1/302 for energy saving
• CPC Class Codes: B66B 1/308 with AC powered elevator drive
• CPC Class Codes: Y02B 50/00 Energy efficient technologies in elevators, escalators and moving walkways, e.g. energy saving or recuperation technologies

Abstract

An elevator system uses a supercapacitor to store electric energy. Furthermore, the supercapacitor can be used as a source of reserve power in emergency situations, such as power failures. The supercapacitor is connected together with three switching branches to a rectified signal of the power supply of the motor. By closing and opening the switches, the supercapacitor can be charged when the motor load is small. When the motor load is large or when the power supply fails, the electric energy contained in the supercapacitor can be discharged for use by the motor. In an emergency, the motor drives the elevator at a speed lower than normal, and therefore a supply voltage lower than normal is sufficient. Also, energy obtained from braking of the elevator can be stored in the supercapacitor, which has a storage capacity of considerable magnitude as compared to an ordinary capacitor. By applying the invention, the energy consumption of the elevator can be reduced because the waste energy obtained from the power supply can be stored and utilized when more energy is needed.

Claims

1. A method for storing electric energy needed in an elevator system and for supplying the elevator system with reserve power, comprising:

placing a supercapacitor in the electricity supply circuit of the elevator motor;

pre-charging the supercapacitor with electric energy after start-up of the system;

charging the supercapacitor with electric energy during substantially low energy consumption of the elevator by closing a charging switch; and

discharging electric energy from the supercapacitor to the motor during substantially high energy consumption of the elevator or in the case of a failure of the electric power supply by closing a discharging switch;

conducting the pre-charging current to the supercapacitor via a first switching branch consisting essentially of a series connection of a closed pre-charging switch and a resistor.

2. The method according to claim 1, further comprising:

conducting a charging current to the supercapacitor via a second switching branch consisting essentially of a series connection of a charging switch and a diode.

3. The method according to claim 1, further comprising:

conducting a discharging current via a third switching branch consisting essentially of a discharging switch from the supercapacitor to the motor.

4. The method according to claim 1, further comprising:

charging the supercapacitor with electric energy when the elevator is stationary or traveling with a light load.

5. The method according to claim 1, further comprising:

charging the supercapacitor with electric energy when the elevator is braking.

6. The method according to claim 1, further comprising:

using the supercapacitor as an extra source of electric energy when the elevator is heavily loaded.

7. A method for storing electric energy needed in an elevator system and for supplying the elevator system with reserve power, comprising;

pre-charging the supercapacitor with electric energy, via a first switching branch, after start-up of the system;

charging the supercapacitor with electric energy, via a second switching branch, during substantially low energy consumption of the elevator by closing a charging switch; and

discharging electric energy from the supercapacitor, via a third switching branch, to the motor during substantially high energy consumption of the elevator or in the case of a failure of the electric power supply by closing a discharging switch;

conducting the alternating-current electric energy obtained as power supply into a rectifier;

connecting the first, second and third switching branches in parallel to the rectified power supply signal;

connecting the parallel connection of the switching branches in series with the supercapacitor;

conducting the rectified power supply signal into an inverter; and

conducting the inverted power supply signal to the motor.

8. The method according to claim 7, further comprising:

using the supercapacitor as a source of reserve power when the power supply fails;

conducting a supply voltage substantially lower than in a normal operating condition from the supercapacitor via the inverter to the motor; and

moving the elevator at a velocity supply lower than in a normal operating condition.

9. The method according to claim 7, further comprising:

conducting a pre-charging current to the supercapacitor via the first switching branch consisting essentially of a series connection of a closed pre-charging switch and a resistor.

10. The method according to claim 7, further comprising:

conducting a charging current to the supercapacitor via the second switching branch consisting essentially of a series connection of a charging switch and a diode.

11. The method according to claim 7, further comprising:

charging the supercapacitor with electric energy when the elevator is stationary or traveling with a light load.

12. The method according to claim 7, further comprising:

charging the supercapacitor with electric energy when the elevator is braking.

13. The method according to claim 7, further comprising:

using the supercapacitor as an extra source of electric energy when the elevator is heavily loaded.

14. The method according to claim 7, further comprising:

conducting a discharging current via the third switching branch consisting essentially of a discharging switch from the supercapacitor to the motor.

15. The method according to claim 7, further comprising:

connecting a DC capacitor to the terminals of the output signal of the rectifier.

16. The method according to claim 15, further comprising:

pre-charging the supercapacitor by closing the pre-charging switch when the voltage of the supercapacitor is lower than the voltage of the DC capacitor;

opening the pre-charging switch when the voltage of the supercapacitor reaches the value of the voltage of the DC capacitor; and

charging the supercapacitor by closing the charging switch and opening the discharging switch.

17. A method according to claim 15, further comprising:

discharging electric energy from the supercapacitor to the motor by closing the discharging switch when the voltage of the supercapacitor is higher than the voltage of the DC capacitor and opening the pre-charging switch and the charging switch; and

opening the discharging switch when the voltage of the supercapacitor reaches the value of the voltage of the DC capacitor.

18. The method according to claim 15, further comprising:

charging the DC capacitor by closing the pre-charging switch when the voltage of the supercapacitor is higher than the voltage of the DC capacitor.

19. A system for storing energy needed in an elevator system and for supplying reserve power to the elevator system, comprising:

at least one elevator;

a motor driving said at least one elevator;

further comprising;

a supercapacitor placed in the electricity supply circuit of the elevator motor;

a pre-charging switch to allow the supercapacitor to be pre-charged with electric energy after start-up of the system;

a charging switch to allow the supercapacitor to be charged with electric energy during substantially low energy consumption by the elevator;

a discharging switch to allow electric energy to be discharged from the supercapacitor to the motor during substantially high energy consumption by the elevator or in the case of a failure of the power supply; and

a first switching branch consisting essentially of a series connection of a resistor and the pre-charging switch to allow pre-charging current to be conducted to the supercapacitor.

20. The system according to claim 19, further comprising:

a second switching branch consisting essentially of a series connection of the charging switch and a diode for conducting a charging current to the supercapacitor.

21. The system according to claim 19, further comprising:

a third switching branch consisting essentially of the discharging switch for conducting a discharging current from the supercapacitor to the motor.

22. The system according to claim 19, further comprising:

a supercapacitor for storing electric energy when the elevator is stationary or traveling with a light load.

23. The system according to claim 19, further comprising:

a supercapacitor for storing electric energy when the elevator is braking.

24. The system according to claim 19, further comprising:

a supercapacitor as an extra source of electric energy when the elevator is heavily loaded.

25. A system for storing energy needed in an elevator system and for supplying reserve power to the elevator system comprising:

at least one elevator;

a motor driving said at least one elevator;

a supercapacitor placed in the electricity supply circuit of the elevator motor;

a pre-charging switch to allow the supercapacitor to be pre-charged with electric energy after start-up of the system;

a charging switch to allow the supercapacitor to be charged with electric energy during substantially low energy consumption by the elevator; and

a discharging switch to allow electric energy to be discharged from the supercapacitor to the motor during substantially high energy consumption by the elevator or in the case of a failure of the power supply;

a first switching branch;

a second switching branch;

a third switching branch;

a rectifier for an alternating-current power supply;

a parallel connection of the first, second and third switching branches connected to the output of the rectifier;

a series connection of the parallel connection of the switching branches and the supercapacitor;

an inverter for the rectified power supply signal; and

the motor connected to the output of the inverter.

26. The system according to claim 25, further comprising:

a supercapacitor as a source of reserve power in the case of a failure of the power supply;

control means for conducting a supply voltage substantially lower than in a normal operational condition from the supercapacitor via the inverter to the motor; and

a motor for driving the elevator at a velocity substantially lower than in a normal operational condition.

27. The system according to claim 25, wherein the first switching branch consists essentially of a series connection of a resistor and said pre-charging switch to allow pre-charging current to be conducted to the supercapacitor.

28. The system according to claim 25, wherein the second switching branch consists essentially of a series connection of said charging switch and a diode for conducting a charging current to the supercapacitor.

29. The system according to claim 25, wherein the third switching branch consists essentially of said discharging switch for conducting a discharging current from the supercapacitor to the motor.

30. The system according to claim 25, further comprising:

a supercapacitor for storing electric energy when the elevator is stationary or traveling with a light load.

31. The system according to claim 25, further comprising:

a supercapacitor for storing electric energy when the elevator is braking.

32. The system according to claim 25, further comprising:

a supercapacitor as an extra source of electric energy when the elevator is heavily loaded.

33. The system according to claim 25, further comprising:

a DC capacitor connected to the terminals of the output signal of the rectifier.

34. The system according to claim 33, further comprising:

a pre-charging switch for pre-charging the supercapacitor when the voltage of the supercapacitor is lower than the voltage of the DC capacitor;

a controller of the pre-charging switch for opening the pre-charging switch when the voltage of the supercapacitor reaches the value of the voltage of the DC capacitor; and

a controller of the charging switch and a controller of the discharging switch for charging the supercapacitor by closing the charging switch and opening the discharging switch.

35. The system according to claim 33, further comprising:

a discharging switch for discharging electric energy from the supercapacitor to the motor when the voltage of the supercapacitor is higher than the voltage of the DC capacitor and the pre-charging switch and the charging switch are open; and

a controller of the discharging switch for opening the discharging switch when the voltage of the supercapacitor reaches the value of the voltage of the DC capacitor.

36. The system according to claim 33, further comprising:

a pre-charging switch for charging the DC capacitor when the voltage of the supercapacitor is higher than the voltage of the DC capacitor.