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

Claim 0:
1. A method for AC battery operation, comprising:
determining, at a battery management unit (BMU), which is coupled to an AC battery system comprising a power converter and a battery that is rechargeable, if the battery is charged to a first predetermined capacity;
measuring a battery voltage;
setting an estimated state of charge (SOC) to an upper bound based on a measured battery voltage;
determining, at the battery management unit (BMU), if the battery is discharged to a second predetermined capacity;
remeasuring the battery voltage;
setting the estimated state of charge (SOC) to a lower bound based on a remeasured battery voltage;
enabling a state of a charge (SOC) estimation of the battery based on a set upper bound and a 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.