Desenvolvimento de um carregador portátil para baterias de íons de lítio de 36V

Abstract

This work presents the development of a charger for lithium-ion batteries with a nominal voltage of 36 V, aiming for good efficiency and charge control. This work arises from the increasing demand for electric mobility, with small electric vehicles playing a relevant role, and these being the vehicles that use 36 V batteries. Therefore, research was conducted on the main types of batteries, focusing on lithium models, and on battery charging methods. In addition, the review also focused on power converters, specifically direct current-to-direct current (DC-DC) converters and, more specifically, the flyback converter. With this in mind, an integrated circuit (IC) was chosen for battery charge control, the LTC4000 model, and its control circuit was designed for correct operation. Furthermore, a flyback converter was developed, using a 220V AC mains power source, which was properly rectified and filtered. The switching was controlled by the L6566A IC for efficient high-to-low voltage conversion, providing galvanic isolation. Subsequently, simulations were performed using PSIM software to verify its operation. A printed circuit board was designed and sent for manufacturing. Additionally, a 36V lithium-ion battery pack was designed and assembled, and the transformer winding for the board was completed. The board was then assembled and tested using resistors to verify the system's operation under different load regimes, followed by a charging test of the assembled battery pack. Thus, it was concluded that the system works, despite limitations in the tests, and was able to charge the assembled battery.