Battery charging control

Dr. Yau proposed a two-level system with integrated maximum power point tracking and battery charging control. The system fixes the flaw in the switching control system with a single buck converter and keeps control of the maximum power point tracking and battery charge in the solar power application. The system ensures that the Level-one boost converter enables fast identification of the maximum power point when used with the method of variable step size incremental conductance to achieve stable voltage. The gain value generated by the Level-two PI-controlled charging through the PSO algorithm created provides the system with a hybrid charging method combining both the constant current and voltage. Experimentally, this method has a higher charging rate than any other methods that only relies on constant voltage and ensures effective charging while maintaining stable voltage. It has been successfully applied to the charging of portable solar cells. Its 18F8720 microcontroller enables the Level-one DC/DC boost converter to track the maximum power point of the solar cell, while supplying power to the Level-two DC/DC buck converter to enhance the efficiency of charging. This result was published in the SCI journal Computers & Mathematics With Applications, 2012. Furthermore, Dr. Yau proposed a field-programmable gate array (FPGA) based intelligent sun tracking system with dual-axis sun tracking function. The system uses the PSO algorithm improved by the logistic map to look for optimal gain parameters of the PI controller of the motor system to effectively control the servomotors and keep the solar panels in a position perpendicular to the sunlight to increase the efficiency of solar radiation. The system uses fuzzy logic to improve the INC (Incremental Conductance) MPPT and makes the solar panel output reach the maximum power point more rapidly and stably than the conventional INC with fixed steps. The sun tracking system is provided with intelligent functions. The solar panels rotate automatically during the daytime, and a delay-time function reduces the electric power consumed by the motor. At night, the solar panels automatically return to their initial positions until the sun rises the next day. Moreover, the system can be manually switched between the dual-axis and one-axis modes depending on the preference of the different users or in different areas and the inclination of the solar panels can be adjusted directly. The result of this multi-function sun tracking system was published in the SCI journal Mechatronics, 2015.