鋁電解電容器雖說是較為常用的一種電子元器件，但其本身很容易受到高溫和低溫等極端條件的影響，而導(dǎo)致元器件損壞。如何有效的規(guī)避這些問題，就要根據(jù)鋁電解電容本身的特性進(jìn)行分析。

　　Although aluminum electrolytic capacitor is a kind of common electronic components, it is easy to be affected by extreme conditions such as high temperature and low temperature, resulting in damage of components. How to avoid these problems effectively depends on the characteristics of aluminum electrolytic capacitor itself.

　　鋁電解電容器在浸透電解液的紙片兩面放置金屬薄片。這種電解液會在電容器壽命期間蒸發(fā)，從而改變其電氣屬性。如果電容器失效，其會出現(xiàn)劇烈的反應(yīng)：電容器中形成壓力，迫使它釋放出易燃、腐蝕性氣體。

　　Aluminum electrolytic capacitors place metal sheets on both sides of the paper soaked in electrolyte. This electrolyte evaporates over the life of the capacitor, changing its electrical properties. If the capacitor fails, it will react violently: pressure is formed in the capacitor, forcing it to release flammable and corrosive gases.

　　電解質(zhì)蒸發(fā)的速度與電容器溫度密切相關(guān)。工作溫度每下降10攝氏度，電容器壽命延長一倍。電容器額定壽命通常為在其最大額定溫度下得出的結(jié)果。典型的額定壽命為105攝氏度下1000小時。

　　The rate of electrolyte evaporation is closely related to the capacitor temperature. When the working temperature drops by 10 ℃, the life of the capacitor is doubled. The rated life of a capacitor is usually the result obtained at its maximum rated temperature. The typical rated life is 1000 hours at 105 degrees Celsius.

　　選擇這些電容器用于圖1所示LED燈泡等長壽命應(yīng)用時（LED的壽命為25000小時），電容器的壽命便成了問題。要想達(dá)到25000小時壽命，這種電容器要求工作溫度不超過65攝氏度。這種工作溫度特別具有挑戰(zhàn)性，因為在這種應(yīng)用中，環(huán)境溫度會超出125攝氏度。

　　When these capacitors are selected for long-life applications such as the LED bulb shown in Figure 1 (the LED life is 25000 hours), the capacitor life becomes an issue. To achieve a life of 25000 hours, the capacitor requires an operating temperature of no more than 65 degrees Celsius. This operating temperature is particularly challenging because in this application, the ambient temperature can exceed 125 degrees Celsius.

　　市場上有一些高額定溫度的電容器，但是在大多數(shù)情況下，鋁電解電容器都將成為 LED燈泡壽命的瓶頸組件。

　　There are some capacitors with high rated temperature on the market, but in most cases, aluminum electrolytic capacitors will become the bottleneck component of LED bulb life.

　　圖1:105℃電容器可能不會達(dá)到其聲稱的23年壽命

　　類似鋁電解電容這種壽命溫度依賴度實際影響了降低電容器額定電壓的方法。首先想到的可能是增加電容器額定電壓來最小化電介質(zhì)失效的機(jī)率。但是，這樣做會使電容器的等效串聯(lián)電阻 （ESR）更高。由于電容器一般會具有高紋波電流應(yīng)力，因此這種高電阻會帶來額外的內(nèi)部功耗，并且增加電容器溫度。故障率隨溫度升高而增加。實際上，鋁電解電容器通常只使用其額定電壓的80%左右。

　　Similar to aluminum electrolytic capacitor, the life temperature dependence actually affects the method of reducing the rated voltage of capacitor. The first thought may be to increase the rated voltage of the capacitor to minimize the probability of dielectric failure. However, this will result in a higher equivalent series resistance (ESR) of the capacitor. Since capacitors generally have high ripple current stress, this high resistance will bring additional internal power consumption and increase capacitor temperature. The failure rate increases with the increase of temperature. In fact, aluminum electrolytic capacitors usually use only about 80% of their rated voltage.

　　電容器溫度較低時，ESR急劇增加，如圖2所示。在這種情況下，-40℃下，電阻呈數(shù)量級增加。這在許多方面都會影響到電源性能。如果電容器用于開關(guān)式電源的輸出端，則輸出紋波電壓呈數(shù)量級增加。

　　When the capacitor temperature is low, ESR increases sharply, as shown in Fig. 2. In this case, the resistance increases in an order of magnitude at - 40 ℃. This affects power supply performance in many ways. If the capacitor is used in the output of the switching power supply, the output ripple voltage increases in order of magnitude.

　　另外，在ESR和輸出電容形成的零以上頻率，它讓環(huán)路增益增加一個數(shù)量級，從而影響控制環(huán)路。這會產(chǎn)生一個有振蕩的不穩(wěn)定電源。為了適應(yīng)這種強(qiáng)震動，控制環(huán)路通常會在空間方面做出巨大妥協(xié)，并在更高溫度下工作。

　　In addition, at the frequency above zero formed by ESR and output capacitance, it increases the loop gain by an order of magnitude, thus affecting the control loop. This creates an unstable power supply with oscillations. In order to adapt to this strong vibration, the control loop usually makes a huge compromise in space and works at higher temperatures.

　　圖2:低溫下ESR性能急劇下降

　　通過以上分析可以發(fā)現(xiàn)，延長鋁電解電容的使用壽命，主要是通過控制器工作溫度來實現(xiàn)。

　　Through the above analysis, it can be found that extending the service life of aluminum electrolytic capacitor is mainly realized by the operating temperature of the controller.