电解电容寿命纹波电流测试

★ 当 U2 为正半周并且数值大于电容两端电压 Uc 时，二极管 D1 和 D3 管导通，D2 和 D4 管截止，电流一路流经负载电阻 RL，另一路对电容 C 充电。当 Uc>U2，导致 D1 和 D3 管反向偏置而截止，电容通过负载电阻 RL 放电，Uc 按指数规律缓慢下降。 ★ The diode D1&D3 work, D2&D4 cut off, the current flows through the load reSIStance RL in a loop and charge the capacitor C up when U2 in the positive half circuit and its value exceeding the voltage Uc which is parallel cONnected in the two terminals of capacitor. When Uc exceeds U2, and causes the diode D1&D3 cut off, the capacitor discharge through the load resiSTance RL and Uc decline slowly according to the principle of index function. ★ 当 U2 为负半周幅值变化到恰好大于 Uc 时，D2 和 D4 因加正向电压变为导通状态，U2 再次对 C 充电，Uc 上升到 U2 的峰值后又开始下降；下降到一定数值时 D2 和 D4 变为截止，C 对 RL 放电，Uc 按指数规律下降；放电到一定数值时 D1 和 D3 变为导通，重复上述过程。

★ As the same reason , when U2 in the negative half cIRcuit and the amplitude is even changed to exceed Uc ,the diode D2&D4 work due to the positive voltage and U2 charge capacitor C up again. Uc start to decline 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 according to the principle of index function again. When the discharge to a certain value, pcb 抄板 the diode D1&D3 work again and the cycle repeats.2.测试方法/Test Method

2.1 测试温升计算电容寿命/Life time of capacitor at testing temperature condition 计算寿命公式/ Formula for calculating lifetime： 适用公司/ Corporation suited：Fcon、KSC、TL、TEAPO、CapXon

2.2 测试纹波电流计算电容寿命/Life time of capacitor at testing ripple current condition 计算寿命公式/ Formula for calculating lifetime：

2.2.1 直接测量电容纹波电流/Direct measure of E-cap ripple current 开关电路中电容纹波电流分析 C1 为 buck 电容，其充电时间受到低频交流输入影响，而放电时间则是受到开关管 Q1 的高频影响。即 A 点受到低频交流输入影响，频率为交流频率的 2 倍，100Hz 左右，故 A 点处所测试出电流为电容 C1 的低频纹波电流（IL）；B 点受到高频开关 Q1 的影响，频率一般为 100KHz，故 B 点所测试出的电流为电容 C1 的高频纹波电流（IH）。