Battery state-of-charge calibration

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 (Voc) of the energy storage system following a known Voc-SOC profile;
• measuring Voc;
• and
• estimating SOC as a function of the measured Voc based upon the known Voc-SOC profile.

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 Voc-SOC boundary curve, measuring Voc of the EES system, and estimating SOC as a function of Voc and the Voc-SOC boundary curve.

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 (Voc) of the battery reside on a Voc-SOC charge/discharge boundary loop;
• determining Voc;
• and
• estimating SOC of the battery based upon Voc and the Voc-SOC charge/discharge boundary loop.