Patent ID: 8738311

Claim:
A SOC (state of charge) estimation method applicable to a hardware battery control unit to control a rechargeable battery, applied in a battery management system of an electronic vehicle, comprising: measuring a battery parameter of the rechargeable battery; judging whether the battery parameter of the rechargeable battery is stable; if the battery parameter of the rechargeable battery is not stable, estimating a battery open circuit voltage of the rechargeable battery by a fuzzy control and processing an established experiment data of the rechargeable battery into a 3D (three dimensional) function by the fuzzy control; and calculating a time domain dynamic equation and converting into a SOC function, substituting the SOC function into the fuzzy control to estimate an SOC value, wherein the time domain dynamic equation performing a time domain dynamic monitor; wherein the step of judging whether the battery parameter of the rechargeable battery is stable comprises: during a predetermined period, judging whether the battery current of the rechargeable battery is smaller than a predetermined value and judging whether the battery voltage of the rechargeable battery is stable to judge whether the battery parameter of the rechargeable battery is stable; and the step of calculating the time domain dynamic equation comprises: calculating a first order equivalent circuit of the rechargeable battery; establishing a non-linear function of a capacitor voltage and a battery power status of the rechargeable battery based on the established experiment data of the rechargeable battery; and converting the first order equivalent circuit of the rechargeable battery into the time domain dynamic equation according to the non-linear function.