基于反激式原边反馈控制结构的过零检测方法及实现

Zero-crossing detecting method and achievement based on primary-side controlled flyback structure

本文提出一种基于反激式(Flyback)原边反馈控制结构的电感电流过零检测实现方法,主要应用于临界导通模式(Boundary Conduction Mode,BCM)下的LED恒流控制方案中。分析了传统反激式原边反馈控制结构方案在实现电感电流临界模式控制中的局限性,在此基础上,提出了一种不依赖辅助绕组的过零检测机制。基于0.35um CV800GS工艺,采用Cadence软件对系统进行仿真,结果表明,在不同负载和线电压输入条件下系统能够快速可靠地实现过零检测控制。

This paper proposes a novel inductor current zero-crossing detecting achievement method based on primary-side controlled Flyback structure, which is mainly applied to the BCM （Boundary Conduction Mode） controlled LED constant-current scheme. This paper analyzes the limitation of the traditional primary-side controlled Flyback structure achieving inductor current BCM mode. Based on the analysis, this paper proposes a zero-crossing detecting mechanism independent of auxiliary winding. Based on the 0.35urn CV800GS process, the proposed system is simulated by Cadence software. The simulation results show that the system can fast and reliably achieve zero-crossing detecting control under different loads and line input voltages.