This report presents the process of design and implementation of a battery charger for a Li-ion battery. The development of this battery charger includes the component from Linear Technology LTC4015. This component integrates the functions of a battery charger configured as a buck (step-down) converter. This device must be integrated in a Printed Circuit Board with a specific design. Also, it must be configured using a microcontroller named Raspberry Pi, which also performs the measurements.
The method of design is divided in two parts. One is focused on developing the printed circuit board, which includes the simulation of the device and the development of the PCB, and the second one is focused on developing the program used in the microcontroller to manage the operation of the LTC4015.
The result is a charge controller device that can be used with different configurations with a buck converter topology. The different parts of the design process are the simulation, the design and the implementation. Each of these parts have a section of results in this report. The simulation section includes results obtained with LTSpice and the device LTC4020, which is a similar device to the LTC4015 but without the Maximum Power Point Tracking mode, which is not modelled in LTSpice.
PV is the main power source considered to charge the battery, and is carefully studied in this project. The PV input is studied with LTSpice, first simulating the I-V curve of the schematic of the solar cell. Second, integrating a solar cell in the simulation of the LTC4015. Third, operating the device LTC4015 with a solar panel that is also characterized.
The design section includes the electronic components used for the development of the board that integrates the charge controller, the LTC4015 in this case, based on the calculations performed for the requirements of the LTC4015. Finally, the implementation section includes the description of the board implemented but also the description of the configuration and measurement code.
The conclusions presented in this report show that the LTC4015 is a battery buck charger with different functions that make it suitable to be used in different solar applications. Also, this report opens new future work lines, such as the full characterization of the board, the implementation of a test bench and the integration of the board in different applications for solar energy systems.