BATTERY STATE-OF-CHARGE CALIBRATION

• US 20110226559A1
• Filed: 11/17/2008
• Published: 09/22/2011
• Est. Priority Date: 11/17/2008
• Status: Active Grant

• Current Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Original Assignee: Otis Elevator Company (Otis Worldwide Corp.)
• Inventors: Chen, Lei, Oggianu, Stella M., Veronesi, William A., Blasko, Vladimir
• Granted Patent: US 8,887,872 B2
• Time in Patent Office: Days
• US Class Current: 187/290
• CPC Class Codes: B66B 1/308 with AC powered elevator drive
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 35/005 Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references G01R33/0035, G01R35/002 take precedence

Abstract

Calibration of the state-of-charge (SOC) of a battery-based energy storage system used with a regenerative drive uses an SOC-open circuit voltage (V?oc#191) correlation. The battery is partially charged or discharged to assure operation defined by V?oc#191 following a known V?oc#191-SOC profile, such as a charge or discharge boundary curve. The partial charging/discharging may be synchronized with a traffic profile of an elevator system driven by the regenerative drive. A V?oc#191 measurement is made, and by enhancing the relaxation dynamics of V?oc#191 through regulating battery usage with a reference to traffic profile, a V?oc#191 is estimated more reliably. Using the estimate V?oc#191 and the known V?oc#191-SOC profile, state-of-charge of the battery is determined.

Claims

1. A method of determining state-of-charge (SOC) of a battery, the method comprising:

changing the SOC of the battery over a portion of a full SOC range to assure operation defined by open circuit voltage (V_oc) of the battery following a known V_oc-SOC profile;

determining a V_oc value; and

estimating SOC of the battery based upon the V_oc value and the known V_oc-SOC profile.

2. The method of claim 1 and further comprising:

determining whether SOC is above a desired SOC range.

3. The method of claim 2, wherein changing SOC of the battery comprises decreasing SOC of the battery if SOC is above the desired SOC range, and increasing SOC if SOC of the battery if SOC is not above the desired SOC range.

4. The method of claim 1, wherein changing SOC of the battery is over a portion of up to about 80% of the full SOC range.

5. The method of claim 1, wherein the known V_oc-SOC profile comprises a charge/discharge boundary loop.

6. The method of claim 5, wherein changing SOC comprises charging the battery to a charge profile of the boundary loop.

7. The method of claim 5, wherein changing SOC comprises discharging the battery to a discharge profile of the boundary loop.

8. The method of claim 1, wherein changing SOC comprises operating the battery with a series of micro-cycles comprising both charging and discharging.

9. The method of claim 8, wherein the series of micro-cycles are produced by operation of a regenerative drive of an elevator system.

10. The method of claim 9 and further comprising:

synchronizing the changing of SOC with a traffic profile of the elevator system.

11. The method of claim 10, wherein determining a V_oc value occurs during an open circuit of short time duration by counteracting prior SOC changing trend to enhance voltage relaxation dynamics through regulating the battery usage with a reference to the traffic profile.

12. The method of claim 8, wherein determining a V_oc value is based on the measured V_oc and voltage relaxation characteristics of the V_oc.

13. A method for determining state-of-charge (SOC) of an energy storage system of a regenerative drive elevator system, the method comprising:

partially charging or discharging the energy storage system to assure operation defined by open circuit voltage (V_oc) of the energy storage system following a known V_oc-SOC profile;

measuring V_oc; and

estimating SOC as a function of the measured V_oc based upon the known V_oc-SOC profile.

14. The method of claim 13, wherein partially charging or discharging the energy storage system changes SOC by up to 80% of a full SOC range.

15. The method of claim 13, wherein the known V_oc-SOC profile comprises a charge/discharge boundary loop.

16. The method of claim 13, wherein partially charging or discharging is produced by a series of micro-cycles.

17. The method of claim 16, wherein the series of micro-cycles are produced by operation of the regenerative drive elevator system along with grid power.

18. An elevator system comprising:

a regenerative drive;

a hoist motor operated by the regenerative drive;

an electrical energy storage (EES) system connected to the regenerative drive; and

an EES system controller for controlling charging and discharging of the EES system as function of state-of-charge (SOC), and for performing SOC calibration by charging or discharging the EES system to a known open circuit voltage V_oc-SOC boundary curve, measuring V_oc of the EES system, and estimating SOC as a function of V_oc and the V_oc-SOC boundary curve.

19. The elevator system of claim 18, wherein the EES system controller charges or discharges the EES system during SOC calibration to produce a change of SOC of up to about 80% of a full SOC range.

20. The elevator system of claim 18, wherein the EES system controller charges or discharges the EES system during SOC calibration with a series of micro-cycles produced by operation of the regenerative drive.

21. The elevator system of claim 20, wherein the EES system controller synchronizes the SOC calibration with a traffic profile of the elevator system.

22. A method of determining state-of-charge (SOC) of a battery, the method comprising:

changing SOC of the battery over a portion of a full SOC range so that SOC and open circuit voltage (V_oc) of the battery reside on a V_oc-SOC charge/discharge boundary loop;

determining V_oc; and

estimating SOC of the battery based upon V_oc and the V_oc-SOC charge/discharge boundary loop.

23. The method of claim 22, wherein changing SOC of the battery comprises decreasing SOC of the battery if SOC is above the desired SOC range, and increasing SOC if SOC of the battery if SOC is not above the desired SOC range.

24. The method of claim 22, wherein changing SOC of the battery is over a portion of up to about 80% of the full SOC range.

25. The method of claim 22, wherein changing SOC comprises charging or discharging the battery with a series of micro-cycles.