Current‐fed isolated PFC pre‐regulator for multiple LED lamps with extended lifetime
Current‐fed isolated PFC pre‐regulator for multiple LED lamps with extended lifetime
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DOI：
10.1002/cta.754
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发表时间：
2012-08
影响因子：
2.3
通讯作者：
X. Qu;Siu‐Chung Wong;C. Tse
中科院分区：
文献类型：
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作者：
X. Qu;Siu‐Chung Wong;C. Tse
为了发出高质量的LED光，一个或一箱LED灯通常由PWM控制的恒流源驱动，以最大限度地减少器件变化并实现精确的亮度控制。由离线交流电源供电，前端电源转换器应该为后端LED电流调节器的输入提供相对较低的直流电压母线。为了匹配LED的长寿命，整个LED驱动器（镇流器）应该像LED一样耐用。然而，驱动器的寿命通常受到传统PFC预调节器中使用的高压电解电荷存储电容器的限制。在本文中，我们之前提出的谐振电流馈电隔离PFC预稳压器被扩展到在不连续传导模式（DCM）下工作。它允许在变压器二次上使用低压存储电容器，因此延长了LED照明系统的整体寿命。给出了计算低压电解电容器预期寿命的详细方法。和前面一样，主开关上的高压应力，这是电流馈电隔离变换器的典型特征，通过利用谐振所需的变压器漏感，大大降低了主开关上的高压应力。此外，使用双非级联结构保证了高效率。采用稳态状态空间平均分析方法设计了DCM工作下的变换器。建立了一个原型转换器来验证所提出的PFC LED预调节器的性能。版权所有©2011 John Wiley & Sons， Ltd
To emit high‐quality LED light, one or a bin of LED lamp(s) is normally driven by a PWM‐controlled constant current source to minimize device variation and achieve accurate brightness control. Powered from offline AC mains, the front‐end power converters should provide a relatively low DC voltage bus for the inputs of post‐end LED current regulators. To match the long lifetime of LEDs, the whole LED driver (ballast) should work as durably as the LEDs. However, the lifetime of the driver is usually limited by the high‐voltage electrolytic charge storage capacitors used in conventional PFC pre‐regulators. In this paper, our previously proposed resonant current‐fed isolated PFC pre‐regulator is extended to operate in discontinuous conduction mode (DCM). It allows the use of the low‐voltage storage capacitors on the transformer secondary, and therefore extends the overall lifetime of the LED lighting system. A detailed procedure for finding the expected lifetime of the low‐voltage electrolytic capacitor is given. As before, the high‐voltage stress on the main switches, which is typical in current‐fed isolated converters, is reduced substantially by taking advantage of the transformer leakage inductance necessary for resonance. Additionally, high efficiency is ensured by the use of dual non‐cascading structures. Steady‐state state‐space averaging analysis is performed for designing the converter in DCM operation. A prototype converter is built to verify performance of the proposed PFC LED pre‐regulator. Copyright © 2011 John Wiley & Sons, Ltd.