分段導通線性LED驅動電路

Abstract

近年地球氣候暖化及能源匱乏的問題，促使世界各國相繼提出節約能源、提高能源使用效率及具體抑制溫室氣體排放量的行動方案，照明節能是其中重要的一個部份。全球各國皆紛紛推出汰換白熾燈的時間表及LED燈泡的安全規範、電磁兼容規範及節能規範，以求LED燈泡可取代能源效率僅有其1/4的白熾燈泡。 LED燈泡取代傳統白熾燈泡在LED驅動器設計上常遇到許多的問題，例如線性LED驅動電路效率低下的問題、切換式LED驅動電路的電磁干擾問題及兩者在調光應用時都有的閃爍及為解決閃爍所產生的耗能等問題，往往每種驅動電路架構都會有其較難處理的問題，為解決這些問題通常會使成本增加，導致LED燈泡取代傳統白熾燈時遇到瓶頸。 傳統線性LED驅動電路架構簡單，且其特色即是不會產生電磁干擾的問題。本論文所提出的分段導通線性LED驅動電路是改良自傳統線性LED驅動電路，取其無電磁干擾的優點，利用分段導通的方式改善其效率低下的問題，並克服在常見的TRIAC調光應用中遇到的閃爍及耗能問題。本論文實現了分段導通線性LED驅動電路的理論，證明本論文的理論不但克服上述的問題，也符合安全規範及能源規範的要求，並提出及驗證最佳化的設計方式，提升LED燈泡發光效率。

Global warming and energy shortage in recent years have led the world countries to propose energy saving plan, energy efficiency improving plan, and greenhouse gas inhibiting plan. Energy saving of lighting is an important part. Countries of world have made safety certifications, EMI certifications, energy saving certifications, and incandescent replacement schedules. LED bulbs can replace incandescent bulbs with low energy efficiency. LED bulbs for replacing conventional incandescent bulbs often have many problems in the design of the LED drivers. For example, the linear LED driver circuit has inefficient problem while the switching LED driver circuit has the EMI problem. Besides, dimming flicker problem and power loss problem in bleeding circuit also deteriorate the LED performance. To solve these problems, designer often needs to increase the cost. As a result, it caused the replacement of conventional incandescent bulbs by LED encounters many difficulties. Conventional linear LED driver structure is very simple. Linear LED diver features to remove the EMI problem. The proposed multi-step linear LED driver circuit is a modification of conventional linear LED driver circuit. Multi-step linear LED driver not only has no EMI problem but also improves the power conversion efficiency. Simultaneously, it solves the flicker issue and energy loss in TRIAC dimmer applications. This paper realized the theory of multi-step linear LED driver, and proved that the theory of multi-step linear LED driver can meet safety and energy saving certifications. This paper also proposed and verified the optimized design method to enhance LED bulbs luminous efficiency.