Patent ID: 11936232
Assignee: ENPHASE ENERGY, INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 19:
20. An AC battery system, comprising:
a battery that is rechargeable;
a battery management unit (BMU) coupled to the battery;
a power converter coupled to the battery and the BMU; and
a controller configured to:
determine, at the BMU, if the battery is charged to a first predetermined capacity;
measure a battery voltage;
set an estimated state of charge (SOC) to an upper bound based on a measured battery voltage;
determine, at the battery management unit (BMU), if the battery is discharged to a second predetermined capacity;
remeasure the battery voltage;
set the estimated state of charge (SOC) to a lower bound based on a remeasured battery voltage;
enable a state of a charge (SOC) estimation of the battery based on the set upper bound and the set lower bound; and
transitioning from a ready to charge state to an under voltage lockout state when a first period of time passes and the state of charge (SOC) measured by the battery management unit (BMU) falls below a minimum threshold and after a second period of time passes in the under voltage lockout state, transitioning to a low power survival state.