| 摘要 |
The state of charge of an industrial truck drive battery is determined from the internal cell voltage of the battery which is determined with the aid of the determined dynamic internal resistance Ri. Terminal voltage u and current 2 are measured 1,2; differentiated 10,11 with respect to time; divided 12 and filtered 13 to calculate a dynamic internal resistance value Ri; which can be multiplied by current i to give a voltage drop Udrop which can be added to terminal voltage u to give a cell voltage Ucell. A diffusion overvoltage (fig 1, 4) can be determined empirically as a function of the power drawn and used to compensate the internal cell voltage to give an internal open circuit voltage that can be used to calculate the state of charge. The residual capacity can therefore be calculated for an industrial truck that uses one battery or more. Also analysing the internal open circuit voltage over time can indicate a damaging deep discharge, should the value change within a time interval by more than a predetermined value. The state of charge may be displayed (fig 1, 8) and may be used by a controller (fig 1, 7) to control loads ensuring that safety-related functions are maintained when there is a low state of charge. |
