Power source as an energy saver and emergency power source in an elevator system

• US 20070163844A1
• Filed: 12/26/2006
• Published: 07/19/2007
• Est. Priority Date: 07/12/2004
• Status: Active Grant

• Current Assignee: Kone Corporation
• Original Assignee: Kone Corporation
• Inventors: Jahkonen, Pekka
• Granted Patent: US 7,331,426 B2
• Time in Patent Office: Days
• 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

The present invention describes a method and an apparatus for storing electric energy needed in an elevator system into a supercapacitor. Furthermore, the invention 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, characterized in that the method comprises the steps of:

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

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.

2. A method according to claim 1, characterized in that the method further comprises the step of:

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

3. A method according to claim 2, characterized in that the method further comprises the step of:

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

4. A method according to claim 1, characterized in that the method further comprises the step of:

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

5. A method according to claim 1, characterized in that the method further comprises the step of:

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

6. A method according to claim 1, characterized in that the method further comprises the steps of:

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 the inverter; and

conducting the inverted power supply signal to the motor.

7. A method according to claim 1, characterized in that in that the method further comprises the step of:

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

8. A method according to claim 1, characterized in that the method further comprises the step of:

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

9. A method according to claim 1, characterized in that the method further comprises the step of:

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

10. A method according to claim 1, characterized in that the method further comprises the steps of:

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.

11. A method according to claim 1, characterized in that the method further comprises the steps of:

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.

12. A method according to claim 1, characterized in that characterized in that the method further comprises the step of:

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.

13. A method according to claim 1, characterized in that the method further comprises the steps of:

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.

14. A method according to claim 1, characterized in that in that the method further comprises the step of:

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

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

at least one elevator;

a motor (13) driving the elevators;

characterized in that the system further comprises;

a supercapacitor (19) placed in the electricity supply circuit of the elevator motor (13);

a charging switch (14) to allow the supercapacitor (19) to be charged with electric energy during substantially low energy consumption by the elevator; and

a discharging switch (16) to allow electric energy to be discharged from the supercapacitor (19) to the motor (13) during substantially high energy consumption by the elevator or in the case of a failure of the power supply.

16. A system according to claim 15, characterized in that the system further comprises:

a pre-charging switch (15) to allow the supercapacitor (19) to be pre-charged with electric energy after start-up of the system.

17. A system according to claim 16, characterized in that the system further comprises:

a first switching branch consisting of a series connection of a resistor (18) and the pre-charging switch (15) to allow pre-charging current to be conducted to the supercapacitor (19).

18. A system according to claim 15, characterized in that the system further comprises:

a second switching branch consisting of a series connection of the charging switch (14) and a diode (17) for conducting a charging current to the supercapacitor (19).

19. A system according to claim 15, characterized in that the system further comprises:

a third switching branch consisting of the discharging switch (16) for conducting a discharging current from the supercapacitor (19) to the motor (13).

20. A system according to claim 15, characterized in that the system further comprises:

a rectifier (10) for an alternating-current power supply;

a parallel connection of the first (18, 15), second (17, 14) and third (16) switching branches connected to the output of the rectifier (10);

a series connection of the parallel connection of the switching branches and the supercapacitor (19);

an inverter (12) for the rectified power supply signal; and

the motor (13) connected to the output of the inverter (12).

21. A system according to claim 15, characterized in that the system further comprises:

a DC capacitor (11) connected to the terminals of the output signal of the rectifier (10).

22. A system according to claim 15 characterized in that the system further comprises:

a supercapacitor (19) for storing electric energy when the elevator is stationary or traveling with a light load.

23. A system according to claim 15, characterized in that the system further comprises:

a supercapacitor (19) for storing electric energy when the elevator is braking.

24. A system according to claim 15, characterized in that the system further comprises:

a pre-charging switch (15) for pre-charging the supercapacitor (19) when the voltage of the supercapacitor (19) is lower than the voltage of the DC capacitor (11);

a controller of the pre-charging switch (15) for opening the pre-charging switch (15) when the voltage of the supercapacitor (19) reaches the value of the voltage of the DC capacitor (11); and

a controller of the charging switch (14) and a controller of the discharging switch (16) for charging the supercapacitor (19) by closing the charging switch (14) and opening the discharging switch (16).

25. A system according to claim 15, characterized in that the system further comprises:

a discharging switch (16) for discharging electric energy from the supercapacitor (19) to the motor (13) when the voltage of the supercapacitor (19) is higher than the voltage of the DC capacitor (11) and the pre-charging switch (15) and the charging switch (14) are open; and

a controller of the discharging switch (16) for opening the discharging switch (16) when the voltage of the supercapacitor (19) reaches the value of the voltage of the DC capacitor (11).

26. A system according to claim 15, characterized in that the system further comprises:

a pre-charging switch (15) for charging the DC capacitor (11) when the voltage of the supercapacitor (19) is higher than the voltage of the DC capacitor (11).

27. A system according to claim 15, characterized in that the system further comprises:

a supercapacitor (19) 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 (19) via the inverter (12) to the motor (13); and

a motor (13) for driving the elevator at a velocity substantially lower than in a normal operational condition.

28. A system according to claim 15, characterized in that the system further comprises:

a supercapacitor (19) as an extra source of electric energy when the elevator is heavily loaded.