EXPERIMENTAL VALIDATION OF AN UNKNOWN INPUT ESTIMATION ALGORITHM FOR LITHIUM ION BATTERY APPLICATIONS

Open Access
Author:
Norouzi, Peyman
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Dr. Hosam Fathy, Thesis Supervisor
  • Dr. Jacqueline O’Connor, Honors Advisor
Keywords:
  • Battery
  • estimation
  • lco
  • lfp
  • input current
  • current
  • soc
  • kalman filter
  • state space
  • lithium-ion
  • voltage
  • experimental
  • simulation
  • matlab
  • arbin
  • cycler
Abstract:
The thesis develops an experimental setup to validate a model-based algorithm for combined state and current estimation in a lithium-ion battery. The algorithm estimates external (input) current based on the measured terminal voltage. This is useful where current measurement is of interest, but it is either not possible to measure directly or it is too costly for smaller budgeted applications. A paper by Mishra et al. has already theoretically analyzed and validated the algorithm. Although important, the theoretical analysis does not offer a comprehensive picture of the algorithm’s success because the reduced-order model for estimation cannot fully capture the battery’s dynamic. Thus, an experimental investigation becomes necessary. The results of the experiments indicate that the proposed algorithm cannot by itself successfully predict and track the external current and internal state of a battery in the case of Lithium Cobalt Oxide (LCO) and Lithium Iron Phosphate (LFP) lithium-ion batteries. An addition of a 0.5 Ω resistor improves the performance of the algorithm immensely in estimating the input current of the battery. This improvement shows that algorithm can be useful in estimating the input current of a lithium-ion battery without a current sensor if an additional external resistor is used.