A novel light load solution for LLC series resonant converter

作者：Yiqing Ye, Chao Yan, Jianhong Zeng, Jianping Ying · 年份：2007 · DOI：10.1109/intlec.2007.4448738 · 被引用次数：26 · 研究领域：Advanced DC-DC Converters、Wireless Power Transfer Systems、Advanced Power Amplifier Design

LLC series resonant topologies has many unique characteristics and improvements over PWM topologies. However, at light load or open load, the unstable output voltage is one of critical issues of LLC-SRC which uses diodes as rectifiers. The traditional solution employs dummy load, nevertheless it results in high dummy load loss and low system efficiency. This paper analyzed the root cause that result in the open load issue and proposed a simple and practical solution, which can stabilize the output voltage at no dummy load and make LLC series resonant converter work in a narrow frequency range. At last, the solution is employed in a 580 kHz, 54V/50A telecom power supply and the LLC circuit operating frequency is 748 kHz with 15W total losses, rather than 1MHz with 200W total losses in an unstable case.