Research on Unwinding Tension Control of Lithiumion Battery Stacking Machine Based on Sliding Mode Control

Tension control is a key technology to ensure the high-precision and efficient manufacturing of lithium-ion batteries. The tension control of the separator unwinding section of the lithium-ion battery stacking machine is very challenging due to the time-dependent coil radius and errors in coil radius estimation. To this end, the tension model of separator unwinding section was constructed and a sliding mode control (SMC) strategy was adopted, which is combined with the extended state observer (ESO) to compensate the coil radius perturbation and achieve tension stability of separator unwinding section. The effect of tension control was tested on the experimental platform. The results show that compared with the conventional variable proportional control strategy, the designed sliding mode control strategy is more robust in the tension control and more adaptable to the condition of coil radius perturbation. In view of the fact that the traditional variable proportion control strategy can not guarantee the tension fluctuation at ± 5%, the designed sliding mode control strategy can control the tension fluctuation within the range of $-4.1 \% \sim+4.8 \%$ at different coil radius.