Highly Efficient Nonisolated Constant Output Current LCC Resonant Converter With Wide Input Voltage Range

In this article, we propose a simple structure highly efficient low-element-count nonisolated constant output current resonant converter for wide input voltage range and high-efficient applications. The converter is developed by combining a basic buck–boost converter with a half-bridge LCC resonant converter to improve the adjustable voltage conversion ratio. In the proposed structure, most of the output power is fed directly, which reduces the conduction power losses and increases efficiency by the reduction of the processed power, and the switches and rectifier diodes' voltage stress is significantly decreased due to cascaded outputs structure. It operates at the resonant frequency to achieve a constant output current feature for applications, such as LED drivers and battery chargers, and the output current is regulated by the pulsewide modulation. The proposed converter can achieve zero-voltage switching operation for all switches and zero-current switching operation for all diodes over a wide range of the input voltage and load conditions. The proposed structure is analyzed in detail. To verify the proposed converter performance, a 21-W laboratory prototype is realized and tested for the wide input voltage range of 12–40 V to provide 350 mA output current. The proposed converter achieves a high peak efficiency of 98.15%.