[기술]알루미늄 전해 캐패시터를 LED 드라이버에 사용하면 LED 조명 수명이 단축될까?

• 2018-08-01

요약 내용: 

전해 캐패시터의 역할은 1차, 2차로 구분되며 에너지 저장 및 필터링 기능을 가지고 있습니다. 

구체적으로 1차는 서지 에너지를 흡수하고 순간적인 전력 변화로 인한 깜박임을 방지하며 EMI를 낮춥니다. 2차는 주로 필터링에 사용되어 저주파 전류 리플을 낮추고 플리커를 개선합니다.

 LED 조명기구 수명에 영향을 미치는 주요 요인은 온도와 광원, 드라이버의 전해 커패시터입니다.

 일반적인 LED의 평균 수명은 15,000시간이며, 고전력 LED인 경우 50,000시간 정도입니다. 

LED 드라이버의 수명은 LED 수명보다 짧으면 안됩니다. 

HLG-150H-24를 예로 들면 출력단 캐패시터는 최고 105℃에서 10,000시간의 전해 캐패시터이지만, 

실제 테스트(주변온도 60℃)를 기준으로 제품 수명 시간은 70,000시간이며, 주변 온도가 줄어들수록 수명은 더 늘어날 것으로 예상되기 때문에 LED 드라이버에 전해 캐패시터를 사용하는 것이 등기구의 수명에 영향을 미치는지 여부보다,

LED 수명을 향상시키는데 정말 중요한 요소는 고효율 회로 및 고품질 전해 캐패시터를 사용하는 LED 드라이버를 선택하는것이 가장 중요합니다.

Energy saving has been the topic drawing worldwide attention. The energy consumption from lighting is about 19~20% of the overall global consumption; if LED is the source of lighting, it sufficiently achieves the advantages of electricity saving and long lifetime. Therefore, the market of LED lighting has been vastly growing and fast replacing all kinds of conventional lighting in various kinds of application fields, such as household lighting, industrial lighting, business lighting, street lighting, automobile lighting, plant house lighting, etc. It is the most significant direction governments all over the world is move forward to for energy saving and carbon reduction policy.

However, it has been a long-time open argument whether using electrolytic capacitors in LED drivers leads to a relatively low lifetime for luminaire. Generally speaking, LED driver solution is categorized into isolated type and non-isolated type. Due to safety concern, the majority of the customers select the isolated type LED driver and almost all of the LED drivers in market use electrolytic capacitors. MEAN WELL has been dedicated in research and development, with the adherence to high quality, for switching power supply. This article provides an in-depth discussion about the role the electrolytic capacitors play in LED drivers and their lifetime performance.



The role electrolytic capacitors play in LED drivers

Roughly speaking, from the application perspective, electrolytic capacitors for isolated LED drivers are divided into primary capacitors (Cp) and secondary capacitors (Cs) and both have the function of energy storage and filtering. Cp, for EMC solution, does not only absorb the surge energy and prevent flickers resulting from instantaneous power change but also lowers EMI; Cs on the output side is mainly used for filtering, lowering the low frequency current ripple and leading to the improvement for flickers. Many low wattage LED drivers in current market, in order to follow the power factor and harmonic current related norms and to meet the demand for low cost, adopt the single stage flyback without Cp or the PSR topology. The omission of Cp results in the need of additional components for surge test solution; on the other hand, with the output ripple, it cannot meet the demand for low flickers (the low frequency flux change rate is lower than 8%.)



LED luminaire lifetime factor

The key factors influencing LED luminaire lifetime are the electrolytic capacitors the light source and the driver use, which are directly related to temperature. The specified lifetime for current lighting units in market is as low as 15,000 hours and as high as 50,000 hours. According to the data provided from the major LED supplier, per LM-80 or TM-21 test, the average lifetime of general high power LED is 50,000 hours or so (the diagram hereunder is from Cree.) The lifetime of LED driver depends on the product level and temperature of the electrolytic capacitors; as a reasonable design practice, it is not supposed to be lower than the lifetime of LED.

MEAN WELL LED driver lifetime