LINE CURRENT AND ENERGY STORAGE CONTROL FOR AN ELEVATOR DRIVE

• US 20110139550A1
• Filed: 08/15/2008
• Published: 06/16/2011
• Est. Priority Date: 08/15/2008
• Status: Active Grant

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Veronesi, William A.
• Granted Patent: US 8,613,344 B2
• Time in Patent Office: Days
• US Class Current: 187/290
• CPC Class Codes: B66B 1/302 for energy saving
• CPC Class Codes: B66B 5/027 to permit passengers to leave an elevator car in case of failure, e.g. moving the car to a reference floor or unlocking the door
• CPC Class Codes: Y02B 50/00 Energy efficient technologies in elevators, escalators and moving walkways, e.g. energy saving or recuperation technologies

Abstract

Power distribution is managed between a regenerative drive (10) connected to an elevator hoist motor (12), and a primary power supply (20) and electrical energy storage (EES) system (36) connected to the regenerative drive. A state-of-charge (SOC) of the EES system and a primary current flow between the primary power supply and the regenerative drive are measured. A direction and magnitude of secondary current flow between the EES system and the regenerative drive is then controlled as a function of the primary current flow and the SOC of the EES system.

Claims

1. A method for managing power distribution between a regenerative drive connected to an elevator hoist motor, and a primary power supply and electrical energy storage (EES) system connected to the regenerative drive, the method comprising:

measuring a primary current flow between the primary power supply and the regenerative drive;

measuring a state-of-charge (SOC) of the EES system;

controlling a direction and magnitude of secondary current flow between the EES system and the regenerative drive as a function of the primary current flow and the SOC of the EES system; and

maintaining the SOC of the EES system within a limited SOC range except as necessary to maintain the primary current flow below a threshold current.

2. The method of claim 1, wherein the controlling step comprises:

maintaining the primary current flow below the threshold current.

3. The method of claim 2, wherein the maintaining the primary current flow step comprises:

adjusting energy supplied from the EES system to the regenerative drive to address hoist motor power demand that exceeds primary power supply power at the threshold current.

4. The method of claim 1, wherein the controlling step comprises:

storing energy from the regenerative drive to the EES system during periods of negative or zero elevator hoist motor power demand.

6. The method of claim 1, wherein the maintaining step comprises:

storing energy from the regenerative drive to the EES system during periods of negative or zero elevator hoist motor power demand until the SOC of the EES system reaches a maximum threshold SOC.

7. The method of claim 1, wherein the maintaining step comprises:

supplying energy to the regenerative drive from the EES system until the SOC of the EES system reaches a minimum threshold SOC.

21. The method of claim 1, wherein the limited SOC range is sufficiently narrow to allow the EES system to either supply power or receive power to reduce the primary current flow when the primary current flow exceeds the threshold current.

22. The method of claim 1, wherein the maintaining step comprises:

setting a target SOC within the limited SOC range; and

adjusting the SOC of the EES system toward the target SOC in response to power demand of the elevator hoist motor becoming approximately zero.

5. (canceled)

8. A system for managing power distribution between a regenerative drive connected to an elevator hoist motor, and a primary power supply and electrical energy storage (EES) system connected to the regenerative drive, the system comprising:

a current sensor operable to measure a primary current flow between the primary power supply and the regenerative drive;

a state-of-charge (SOC) sensor operable to measure a SOC of the EES system; and

a power management module operable to control a direction and magnitude of secondary current flow between the EES system and the regenerative drive as a function of the primary current flow and the SOC of the EES system such that the power management module maintains the SOC of the EES system within a limited SOC range except as necessary to maintain the primary current flow below a threshold current.

10. The system of claim 8, wherein the power management module is operable to maintain the primary current flow below a threshold current.

11. The system of claim 10, wherein the power management module is operable to adjust energy supplied from the EES system to the regenerative drive to address hoist motor power demand that exceeds primary power supply power at a threshold primary current.

12. The system of claim 8, wherein the power management module is operable to store energy from the regenerative drive to the EES system during periods of negative or zero elevator hoist motor power demand.

14. The system of claim 8, wherein the power management module is operable to supply energy from the regenerative drive to the EES system during periods of negative or zero elevator hoist motor power demand until the SOC of the EES system reaches a threshold SOC.

15. The system of claim 8, wherein the power management module is operable to supply energy to the regenerative drive from the EES system when the SOC of the EES system is above a target SOC.

23. The system of claim 8, wherein the limited SOC range is sufficiently narrow to allow the EES system to either supply power or receive power to reduce the primary current flow when the primary current flow exceeds the threshold current.

9. (None in original)

13. (canceled)

16. A method for managing power distribution between a regenerative drive connected to an elevator hoist motor, and a primary power supply and electrical energy storage (EES) system connected to the regenerative drive, the method comprising:

monitoring a first current flow between the primary power supply and the regenerative drive;

controlling a direction and magnitude of a second current flow between the EES system and the regenerative drive as a function of the first current flow and power demand of the elevator hoist motor; and

maintaining a state-of-charge (SOC) of the EES system within a limited SOC range except as necessary to maintain the first current flow below a threshold current.

first current flow and power demand of the elevator hoist motor.

17. The method of claim 16, wherein the controlling step comprises:

adjusting energy supplied from the EES system to the regenerative drive to address hoist motor power demand that exceeds primary power supply power at a threshold current.

18. The method of claim 16, wherein the controlling step comprises:

storing energy from the regenerative drive to the EES system during periods of negative or zero elevator hoist motor power demand.

20. The method of claim 16, wherein the maintaining step comprises:

storing energy from the regenerative drive to the EES system during periods of negative or zero elevator hoist motor power demand until the SOC of the EES system reaches a maximum threshold SOC; and

supplying energy to the regenerative drive from the EES system until the SOC of the EES system reaches a minimum threshold SOC.

24. The method of claim 16, wherein the maintaining step comprises:

setting a target SOC within the limited SOC range; and

adjusting the SOC of the EES system toward the target SOC in response to power demand of the elevator hoist motor becoming approximately zero.

19. (canceled)