An all-digital battery capacity monitor using calibrated current estimation approach

This paper presents an all-digital battery capacity monitor using calibrated current estimation approach (CCEA). The circuit implementation for state of charge (SOC) and state of health (SOH) estimation methods is also revealed as well. The capacity of the battery is highly correlated with different discharging currents. Due to the variation of the capacity, the accuracy of the SOC and SOH estimated methods will be affected with different discharging currents. The CCEA is used to calibrate the capacity of the battery with different C-rate discharging currents such that the capacity of the battery will be normalized. The proposed design is implemented using a typical 0.25 μm 1P3M 60V BCD process. The core area of the proposed design is 610 × 610 μm
²
. In the range from 0.3 C-rate to 1.0 C-rate, the maximum error of the proposed design is -0.56 % ~ 0.07 %. Particularly, the maximum improvement of the proposed design is 530 %.