驱动LED串的DCM升压转换器简化分析(1)——理论分析

Simplified Analysis of DCM Boost Converter in Driven LED String(1)——Theoretical Analysis

固定频率升压转换器采用不连续导电模式(DCM)工作,能够有效地用于快速调光操作,提供比采用连续导电模式(CCM工作的竞争器件更优异的瞬态响应,这种转换器非常适合于以恒流模式驱动LED串。但驱动LED的升压转换器的交流分析,与使用标准电阻型负载的升压转换器的交流分析不同,在推导最终的传递函数时必须非常审慎。本文分为两个单元:⑴理论分析,介绍如何推导驱动LED串的升压转换器的小信号响应;⑵实际考虑,深入研究实施方案,并验证经验结果及与理论推导比较。

The boost Converter with fixed-frequency adopts a mode of discontinuous conduction（DCM） in working, so that it could operate the fast dimming efficiently, and provide a better transient response than competitor devices which use continuous conduction mode（CCM）, so this kind of converter is suitable for constant-current driven LED string. But the alternating current analysis of boost converter in driven LED is different from that of boost converter using standard resistor-type load, so extra caution should be taken to deduce the final transfer function. This paper is divided into two units： （l）theoretical analysis, introducing how to deduce the small-signal response of boost converter in LED string;（2） practical consideration, lucubrating into the embodiment, confirming empirical findings and comparing theoretical deductions.