Patent ID: 7332892

Claim:
A method for predicting the voltage of a battery, having the following steps: (S 1 ) determining and checking battery data, by detection and calculation devices, with the battery data comprising a battery voltage (U_batt), a battery current (I_batt), a battery temperature (T_batt) and a dynamic internal resistance (Rdi), (S 2 ) checking whether present functional procedure is a first procedure, (S 3 ) if the result in step S 2 is that a functional procedure has already been carried out, checking whether a predetermined time (Tx) has elapsed, and, if the predetermined time has not yet elapsed, returning to step S 1 , (S 4 ) if the predetermined time (Tx) has elapsed, filtering of the battery voltage (U_batt) and of the battery current (I_batt) using a low-pass filter, and emission of a filtered battery voltage (U_filt) and of a filtered battery current (I_filt), (S 5 ) checking whether the filtered battery current (I_filt) is greater than a predetermined load (I_pred) minus a tolerance (Tol), and whether the battery current (I_batt) is greater than a predetermined load current (I_pred) minus the tolerance (Tol) and, if the conditions are not satisfied, returning to step S 1 , (S 6 ) calculation of a resistive voltage drop (U_ri) across the dynamic internal resistance (Rdi), (S 7 ) calculation of a polarization voltage (U_pol) as a function of the filtered battery current (I_batt_filt), (S 8 ) filtering of the polarization voltage (U_pol), using two low-pass filters separately on the basis of a fast settling component (U_pol_fast_raw) and a slowly settling component (U_pol_slow_raw) and emission of a filtered polarization voltage (U_pol_filt), (S 9 ) calculation of a predicted battery voltage by subtracting the resistive voltage drop (U_ri) and the filtered polarization voltage (U_pol_filt) from the filtered battery voltage (U_batt_filt), (S 10 ) limiting of the predicted battery voltage (U_pred) determined in step S 9 upwards and downwards, (S 11 ) filtering of the predicted battery voltage (U_pred), and (S 12 ) checking whether the a bit which indicates that a first function call has been carried out is set and, if not, setting the bit and returning to step S 1 , or, if yes, returning to step S 1 .