A Comprehensive Loss Analysis of Half-Bridge LLC Resonant Converter used in LED Street Lights

High efficient, low-cost and long-term reliable power supplies are today's market demands for LED street lighting applications. To meet these growing demands, the half-bridge (HB) LLC resonant converter has been increasingly gaining importance due to low component count, achieving zero-voltage-switching (ZVS) and zero-current-switching (ZCS) in the whole operating range. Although the HB LLC resonant converter achieves high efficiency and high power density, design process is very complex and reliable power system design based on this topology needs excessive measurements. To overcome these drawbacks, this paper proposes a design approach which takes power losses and thermal considerations into account carefully during design stage. With the suggested method, total product design period is greatly reduced and design reliability is highly improved compared to the conventional design methods. For this purpose, a 100W HB LLC resonant converter based power supply is implemented to confirm the design approach validity. According to the results, power loss of critical items is predicted over 85% accuracy which is high enough for practical purposes. Results and efficiency improvement methods are also discussed at the end of the paper.