Energy management strategy for composite energy storage for mobile robots

In order to enhance power performance of mobile robots and to extend service life of the energy storage without increasing in weight, the battery/supercapacitor composite energy storage was used instead of single battery. The performance of the composite energy storage is determined by the energy management strategy in large extent. The driving current of mobile robots often fluctuates in both low and high frequency range. So an energy management strategy based on both fuzzy control and filtering algorithm was studied. The fuzzy control algorithm determined how the low frequency profile of the driving current was shared between battery and supercapacitor in big time scale. And the filter algorithm decoupled the high frequency component, which was supplied by supercapacitor, from the driving current in small time scale. In the energy management system, the supercapacitor current was controlled via a Bi-DC/DC converter, so that the battery current was regulated indirectly. The effectiveness of the energy management strategy is proved by both the model simulation and the prototype experiment.