電解電容壽命與紋波電流測試

1、電解電容壽命紋波電流測試E-cap Lifetime Test1. 工作原理/ Working principle"200V50Hz仙）電路（b）uo的波形單相橋式整流電容濾波電路及穩(wěn)態(tài)時的波形分析單相橋式幕流電容濾波電路及穩(wěn)態(tài)時的波形分析 當U2為正半周并且數(shù)值大于電容兩端電壓Uc時，二極管D1和D3管導通，D2和D4管截止，電流一路流經(jīng)負載電阻 RL，另一路對電容 C充電。當Uc>U2導致D1和D3管反向偏置而截止，電容通過負 載電阻RL放電，Uc按指數(shù)規(guī)律緩慢下降。 The diode D1&D3 work, D2&D4 cut off, the curr

2、e nt flows through the load resista nee RL in a loop andcharge the capacitor C up when U2 in the positive half circuit and its value exceeding the voltage Uc which is parallel conn ected in the two term in als of capacitor. Whe n Uc exceeds U2, and causes the diode D1&D3 cut off, the capacitor d

3、ischarge through the load resistance RL and Uc decline slowly according to the principle of in dex function. 當U2為負半周幅值變化到恰好大于Uc時，D2和D4因加正向電壓變?yōu)閷顟B(tài)，U2再次對C充電，Uc上升到U2的峰值后又開始下降；下降到一定數(shù)值時D2和D4變?yōu)榻刂?，C對RL放電，Uc按指數(shù)規(guī)律下降；放電到一定數(shù)值時D1和D3變?yōu)閷ǎ貜蜕鲜鲞^程。 As the same reason , when U2 in the negative half circuit and the

4、amplitude is even changed to exceedUc ,the diode D2&D4 work due to the positive voltage and U2 charge capacitor C up aga in. Uc start todecline when it ' s voltage rise to the peak value of U2 and to a certain value , the diode D2&D4 cut off , the capacitor C discharge to RL, Uc decline

5、according to the principle of index function again. When the discharge to a certa in value, the diode D1&D3 work aga in and the cycle repeats.2. 測試方法/ Test Method2.1 測試溫升計算電容壽命/ Life time of capacitor at testing temperature condition計算壽命公式/ Formula for calculat ing lifetimeE廣一LX=L X 2 10 X2c T=

6、Kc*(Tc-Tx)適用公司/ Corporation suited : Feon、KSC、TL、TEAPO、CapXon說明/ Explanation :Lo:is operati ng life of capacita nee SPECTo： is SPEC temperature of capacitorTx:is capacitor ambie nt operati ng temperatureTc： is surface temperature of capacitor caseKc:is coefficie nt from table belowLx:useful life est

7、imati on2.2 測試紋波電流計算電容壽命/ Life time of capacitor at testing ripple current conditionLx=Lo*Kt*Kr計算壽命公式/ Formula for calculat ing lifetime(Kt=2A(To-Tx)/10 Kr=(5- t)/5 t=5*(Ix/Io)A2 )適用公司/ Corporation suited : HEC、JianghaiLo:is operati ng life of capacita nee SPECTo： is SPEC temperature of capacitorTx:

8、is capacitor ambie nt operati ng temperatureIx :is actual value of ripple currentIo:is specified ripple curre ntLx :useful life estimati on2.2.1 直接測量電容紋波電流/ Direct measure of E-cap ripple currentr.開關(guān)電路中電容紋波電流分析C1為buck電容，其充電時間受到低頻交流輸入影響，而放電時間則是受到開關(guān)管Q1的高頻影響。即 A點受到低頻交流輸入影響，頻率為交流頻率的2倍，100Hz左右，故A點處所測試出電流

9、為電容 C1的低頻紋波電流(IL) ； B點受到高頻開關(guān) Q1的影響，頻率一般為 100KHz故B點所測試出的電流為電容 C1的高 頻紋波電流(IH)。C1 is the buck capacitor, its charge time lies on the low freque ncy Vac in put, and the discharge time in flue need by the high freque ncy of switch ing MOSFET Q1. The freque ncy of positi on A, l ying on the Vac in put, is

10、 doubled, about 100Hz. And the curre nt flowed through just is the low freque ncy curre nt of C1; similarly, the freque ncy of positi on B, lying on the Q1, is about 100 KHz, and the curre nt is high freque ncy.目前我司對電容紋波計算方法定義為/The test method defined in our company at present is :血 Flj+陽 F)IIl:Low

11、frequency operating ripple current I L(low Freq) (A)IH：High frequency operating ripple current I H(low Freq) (A)F1:F :Coefficie nt for low freque ncy compe nsati onCoefficie nt for high freque ncy compe nsati onT :Coefficie nt for temperature compe nsati onLx: Actual curre nt2.2.2利用低通和高通濾波電路測量紋波電流/M

12、easurement via low pass or high pass filter對于輸入大容量的電容，有低頻（100HZ ）和高頻（開關(guān)頻率，如 100KHZ ）兩種電流流過，電流的測 量必須串一個電流檢測電阻去獲得，而且低頻紋波電流和高頻紋波電流應分別測量。For bulk capacitor, both low freque ncy (100HZ) and high freque ncy (switch ing freque ncy, say 100 KHz) curre nt are flow ing. The curre nt shall be measured with a c

13、urre nt sense resistor. As the low and high freque ncy ripple shall be measured separately.RUicUo高通濾波電路低通濾波電路低通濾波電路的帶寬為0wc（wc=1/RC），高頻濾波電路帶寬則為 >wc。The bandwidth of low pass filter is 0wc （ wc=1/RC） , and >wc in high pass filter. 在檢測電阻上并接一個RC（ 1k5、0.1uF）電路，（如下圖所示）用有效值表測量0.1uF兩端的有效電壓，即可得低頻紋波電流值，

14、此時高頻成分已被濾除。Add an RC (1K5, 0.1uF) across the sense resistor, measure rms voltage across 0.1uF; this will filter out thehigh freque ncy, leavi ng the 100Hz ripple curre nt.低頻紋波電流測試圖 在檢測電阻上并接一個RC (O.luF、1K5)電路，(如下圖所示)，用有效值表測1K5電阻兩端的有效值電壓，根據(jù)l=U/R即可獲得高頻紋波電流值，此時低頻成分已被濾除。Add a CR (O.luF, 1K5) across the se