Energy-Aware Design of a GaN-Based Dual-Purpose Converter for Standalone Lighting Systems

Energy efficiency plays a crucial role in the development of solar-powered standalone lighting systems, as it directly impacts both the system's autonomy and size, ultimately affecting the cost. In scenarios where a single converter simultaneously functions as both battery charger and LED driver, minimizing energy losses becomes challenging due to the different power levels processed in each mode. The use of gallium nitride (GaN) semiconductors in the converter helps achieving this goal as they allow for a wide range of switching frequencies, maintaining high efficiency even in light-load conditions. However, focusing solely on the converter's efficiency in each task may not necessarily minimize energy losses when considering its 24/7 operating characteristic and charger/driver time ratio. This study introduces a methodology tailored to select circuit components and switching frequencies within a GaN-based dual-purpose converter solution. The primary objective is to maximize system autonomy. A comprehensive analytical model of the converter's losses is paired with a search-based algorithm, enabling the evaluation of commercial components. This evaluation pinpoints the combination that minimizes energy consumption, ultimately leading to a more compact design that efficiently harnesses available resources. Experimental results are showcased for a system with a 30 W driver and 150 W charger, affirming the efficacy of the proposed design methodology. By meticulously selecting parameters, a high-efficiency converter can be realized. This achievement extends the system's autonomy by nearly an hour without necessitating changes to the battery pack's dimensions.