铝电解电容寿命计算PPT

1、技術中心 Benson,2010.04.16,环境温度使的电容器外部 的温度高于内部的温度,纹波电流会产生热量使的电容 器内部的温度高于外部的温度,Key parameters of life 对寿命有影响的主要参数(因素),Ambient Temperature 电容器的环境温度,Self heat rise caused by a Ripple Current 由纹波电流导致的温升,Electrolyte vaporization due to high temperature高温会导致电解液的蒸发,Gassing due to chemical reaction between elec

2、trolyte and oxide 由于电解液和氧化膜之间会发生化学反应,这就导致了气体的产生,Gassing due to electrolyte decomposition 电解液的分解也会导致气体的产生,Mechanism of lifetime 电容器使用寿命的机理,GASSING 气体的产生,INNER PRESURE RISE 电容器内部压力的上升,DIFFUSION THROUGH SEALING RUBBER 电解液会从密封皮头 扩散出来,ELEMENT DRY-UP 芯包变干,OPEN CIRCUIT 开路会产生,Estimation Life Procedure 寿命计算的

3、步骤(程序),Mearsure Ambient Temperature (Tx) 步骤1:测量电容器的环境温度,Get Tx 步骤2:得到温升值,Use Suitable Life Formula 步骤3:选择合适的寿命计算公式,Dummy ECAP. 模拟(虚设)电容器,Actual ECAP. 实际使用的电容器,Measurement Point 环境温度(Tx)测量点,Ambient Temperature 量测环境温度方法 Tx,The Tx should be measured at the place 20-30mm away from the surface of the alu

4、minum case ,at least10mm if the space less than 20mm, and any part adjacent to the capacitor produces heat and causes the temperature(Tx) to be inconstant with places around the capacitor,more than 4 places around the capacitor are preferable to be measured for temperature and then the average value

5、 of the temperatures shall be used as the temperature(Tx) 测量Tx时，测量仪器需放置在离铝表面20-30毫米的地方，最小10毫米，如果有靠近电容器上的部件产生热量或使得 电容器的温度不稳定，需选择4个以上不同的地方进行测量，再取平均值。,STEP 1 步骤 1,STEP 1 步骤 1,Ambient Temperature 环境温度,Notice Please avoid the part which correct temperature can not measure (as below picture ) or measure s

6、everal points, and confirm temperature of the average 注意: 请保证真实温度被测试,或者测试多个位置的温度,然后取其平均值,Cooling parts The position where Gets wind 冷却装置 这个位置可以得到风 ,使得电容器环境温度低,Heating elements 不要使电容器紧挨着发热元器件,4 point of measurement point 测试4个位置的温度,Dummy ECAP. 模拟(虚设)电容器,Actual ECAP. 实际使用的电容器,Measurement Point 环境温度(Tx)

7、测量点,Tx measurement 温升的测量,Ripple Current Calculation 3. 纹波电流的计算,Measure Surface Temperature (Ts) 2. 测量电容器表面温度,Mearsure Inside Core Temperature (Tc) 1. 测量电容器内部中心温度,STEP 2 步骤 2,STEP 2 步骤 2,Tx measurement 1 取得 Tx 值的方法一,Advantage (优点) : More precisely 比较准确 Disadvantage(缺点): Need extra work to make a samp

8、le No useable after measurement 需要额外工作样品(破坏性) 只能在测量时使用,Tx =Core temp. Ambient temp. T x=中心温度(Tc)环境温度(Tx),Insert Thermocouple into inside cap 将热电偶插入电容器里面并把它密封起来,热电耦,Tx,Measure inside core temperature 测量电容器内部中心温度(Tc),STEP 2 步骤 2,Tx measurement 2 取得 Tx 值的方法二,Advantage (优点) : Much better than result of

9、calculation and close to actual measurement Use able even after testing 比通过估算纹波电流和测试中心温度的效果要好,电容器在测试后仍然可以使用 Disadvantage(缺点): Still have extra-job to set up measurement 仍然需要对测试样品做额外的准备工作,Measure surface temperature 测试电容器表面温度(Ts),Tx=(Surface temp. Ambient temp.) x Factor Kc Tx =(表面温度(Ts) -环境温度(Tx) )

10、x 系数(Kc),Please avoid the place where extremely temperature is high or low place 请必要测试最高温度或者最低温度的位置,热电耦,STEP 2 步骤 2,Tx measurement 2 取得 Tx 值的方法二,Measure surface temperature 测试电容器表面温度(Ts),Factor Kc 系数(Kc),STEP 2 步骤 2,Tx measurement 3 取得 Tx 值的方法三,Ripple current calculation 纹波电流估算,Tx=(Actual ripple /Ca

11、talogue ripple) 2x To Tx = (实际纹波电流值(Ix)/目录规定纹波电流值(Io) )2 x额定温升(To),Advantage (优点) : Much easier to get a result 更容易就可以得到结果 Disadvantage(缺点): Actually output is rough estimation. 估算值是粗糙的,误差有点大.,STEP 2 步骤 2,Tx measurement 3 取得 Tx 值的方法三,Ripple current calculation 纹波电流估算,Tx=(Actual ripple /Catalogue rip

12、ple) 2x To Tx = ( 实际纹波电流值(Ix) / 目录规定纹波电流值(Io) )2 x 额定温升(To),Tx=(Actual ripple /Catalogue ripple * Frequency multiplier ) 2x To Tx = ( 实际纹波电流值(Ix) / 目录规定纹波电流值(Io) * 频率系数 )2 x 额定温升(To),No Need Temperature Multiplier 温升不需要考虑温度系数,Tx in proportion to ESR Tx shall not be smaller if ambient temperature is

13、lower! 温升主要取决于ESR. 當環境溫度比較低時,溫升的數值也不會變小,Tx=ESR x (Actual ripple current)2xAb 温升(Tx )=ESR*(实际纹波电流)2 x Ab Ab: Fixed number Ab:固定常数,ESR,Temperature 温度,STEP 3 步骤 3,Life Formula 寿命计算公式,Two Categories 二种类型,Group 1: SUIT TYPE : Chip and other type, general use capacitors 适用范围: 贴片型,一般品,及其它系列 Group 2: SUIT T

14、YPE : SNAP-IN 适用范围:牛角型,SUIT TYPE : Chip and other type, general use capacitors 适用范围: 贴片型,一般品,及其它系列,Group 1,Lx = Lo 2（To-Tx)/10 2(To-Tx)/5,LX=lifetime (hours) of the capacitor to be estimated 计算公式得出的寿命值,Lo=Base (Assured) lifetime (hours) of the capacitor 保证寿命值,To=Maximum rated operating temperature()

15、 最高额定工作温度(85,105,125,130),TX=Actual ambient temperature of the capacitor within device 实际环境温度，即装置内的电容器实际环境温度,TO=Rise in core temperature of the capacitor due to rated (permissible) maximum ripple current. 允许中心温升,即纹波电流升到额定最大值时测得的电容器芯子温升,Tx=Actual rise in the core temperature of the capacitor due to a

16、ctual ripple current at device operating conditions. 实际中心温升,即在装置工作条件下，施加纹波电流而引起的电容器芯子温升,Note: A guide limit of the calculated life time is 15 years Max. 注意:指导意见是推算寿命的最长时间不超过15年,Item: RR 25V680uF 10 x20L 2,000Hr at 105 Condition: Ambient temp=75 Surface temp=85,Example #1,Tx=(Surface temp. Ambient te

17、mp.) x Factor Kc Tx=(表面温度(Ts) -环境温度(Tx) ) x 系数(Kc) = (85-75)X1.15=11.5 10 Factor Kc=1.15,Lx = Lo 2（To-Tx)/10 2(To-Tx)/5 = 2000 X 2(105-75)/10 X 2(5-11.5)/5 = 45,254 Hr = 5.1 years (24 Hr),Group 2,Lx = Lo 2（To-Tx)/10 2(To-Tx)/5 X (Vo/Vx)4.4,LX=lifetime (hours) of the capacitor to be estimated 计算公式得出的

18、寿命值,Lo=Base (Assured) lifetime (hours) of the capacitor 保证寿命值,To=Maximum rated operating temperature() 最高额定工作温度(85,105,125,130),TX=Actual ambient temperature of the capacitor within device 实际环境温度，即装置内的电容器实际环境温度,TO=Rise in core temperature of the capacitor due to rated (permissible) maximum ripple cu

19、rrent. 允许中心温升,即纹波电流升到额定最大值时测得的电容器芯子温升,Tx=Actual rise in the core temperature of the capacitor due to actual ripple current at device operating conditions. 实际中心温升,即在装置工作条件下，施加纹波电流而引起的电容器芯子温升,Note: A guide limit of the calculated life time is 15 years Max. 注意:指导意见是推算寿命的最长时间不超过15年,SUIT TYPE : SNAP-IN 适

20、用范围:牛角型,Vo: Rated Voltage (V) 额定电压,Vx: Actual Input Voltage (V) 实际输入电压,Vx: consider figure,Vx85% x Vo 须考虑的数值,Vx85% x Vo Vo=400, Vx=300 Vo/Vx should not be 400/300, but be 400/340 (400 x 85%) 例: Vo:400 Vx:300 Vo/Vx 不能用 400/300计算,必须使用400/340(400 x85%),Item: LS 450V180uF 25x35L 3,000Hr at 85 项目: LS 450

21、V180uF 25x35L 3,000小时 85度 Condition: Ambient temp=66.4 Surface temp=70 Actual Voltage =394V 情况: 环境温度为66.4度 表面温度为70度 实际工作电压 394V,Example #2,Tx=(Surface temp. Ambient temp.) x Factor Kc Tx=(表面温度(Ts) -环境温度(Tx) ) x 系数(Kc) = (70-66.4)X1.4=5.04 25 Factor Kc=1.4,Lx = Lo 2（To-Tx)/10 2(To-Tx)/5 X (Vo/Vx)4.4

22、= 2000 X 2(85-66.4)/10 X 2(10-5.04)/5 X (450/394)4.4 = 38,870 Hr = 4.4 years (at 24 Hr),Vx: consider figure,Vx85% x Vo 须考虑的数值,Vx85% x Vo 450X85%=382.5V 394 382.5- OK,Estimation Life procedure 寿命估算步骤(程序),Rule 1:Tx 原则1: 温升 Rule 2: 15-year-life is maximum 原则2: 电容器的最大使用寿命应不超过15年,Rules 寿命估算应遵循的原则,Rule 1:

23、Tx 原则1: 温升,Rules 原则,Rules 原则,Note: 需要注意的地方 The actual and rated maximum r.m.s. ripple current shall be equaled in frequency by using frequency multipliers prescribed for each product series in the catalog. 在对产品进行寿命计算时必须要考虑频率系数,所以所采用的实际纹波和最大额定纹波电流应与每种产品目录中规定纹波的频率是一致的 Actual rms ripple current may exc

24、eed the value using the temperature coefficient if the Tx does not exceed the maximum limit. 当温升没有超过最大规定值时,实际纹波电流值也许有可能超过温度系数中规定的最大纹波电流值 TheTx should not exceed the maximum limits. 温升值不应该超过最大规定值,Item: LS 450V180uF 25x35L 3,000Hr at 85 Catalogue ripple=1190mArms/120Hz 例:规格 LS 450V180uF 25x35L 3,000Hr小时在105度 目录纹波电流值1190marms/120Hz Condition: A