Designing a fast charging system for Lithium-Ion batteries based on double pulse method using optimized regulation of frequency and duty cycle

Abstract

Considering the high demand for fast charging in recent times, the pulse charging technique has been identified as one of the fast charging techniques for lithium ion cells to efficiently resolve the limitation of long charging time compared to traditional methods. The pulse charging method is usually considered as a single pulse charging method where it requires two periodic charging stages, one for current injection and the other for resting. A variable frequency and duty cycle are implemented during the single pulse charging method to optimize the acceptable current injection focused on polarization properties. This method has previously proven to charge the lithium ion battery in a time span of 56 minutes with a temperature rise of 13 degrees Celsius. Our thesis aims to prove the effects of the single pulse method and improve the mentioned time and temperature by proposing the use of a double pulse charging method which uses a smaller secondary current between the resting periods of the large primary current without forcing down battery capacity limits. This helps in overcoming the loss of time due to the long resting period without causing raise in temperature. In addition, a current limiting technique was implemented on the primary larger current to lower temperature effects. To do so, MATLAB / Simulink was used to design and implement both charging methods and the results of the proposed method were compared with the single pulse charging strategy. Comparative analysis of our results has shown that the proposed method reduces the charging time almost 10 minutes with no temperature rise compared to the single pulse charging system.