The function of electrolytic capacitor is mainly to filter, that is, to reduce ripple and stabilize current. It is widely used in switching power supply and other products. Its working process can be understood as the process of charging and discharging. Therefore, for an ideal electrolytic capacitor, it does not consume energy, which means that it will not generate heat, but the actual capacitor will generate heat, which is due to the existence of internal resistance.

　　目前，电解电容器主要有两大类，一类是铝电解电容器，另一类就是钽电解电容器了，这两者主要区别是阳极材质有所不同，都是电路较为常用的电解电容。

　　At present, there are two main types of electrolytic capacitors, one is aluminum electrolytic capacitor, and the other is tantalum electrolytic capacitor. The main difference between the two is that the anode material is different. Both are electrolytic capacitors commonly used in circuits.

　　作为电解电容，它的容量一般都是在1μF以上，但是容量在1μF的电容不一定就是电解电容，也有其他的电容，比如独石电容、涤纶电容等。

　　As an electrolytic capacitor, its capacity is generally 1 μ F above, but the capacity is 1 μ The capacitance of F is not necessarily electrolytic capacitance, but also other capacitors, such as monolith capacitor, polyester capacitor, etc.

　　电容的作用有哪些，其实可以这样根据电容名称来理解。

　　What are the functions of capacitance? In fact, it can be understood according to the name of capacitance.

　　1.普通电解电容

　　Common electrolytic capacitor

　　要说普通的电解电容，我们用的最多的莫过于铝电解电容了，这种电容容量大且易发生漏电，适合作为滤波用，但是这种电容内阻大，如下图是电容等效电路图，其中：Rc是漏电阻，Ln是寄生电感，Rn是其他原因引起的损耗电阻。

　　As for ordinary electrolytic capacitors, the most common one we use is aluminum electrolytic capacitors. These capacitors have large capacity and are prone to leakage, so they are suitable for filtering, but their internal resistance is large. The figure below shows the capacitance equivalent circuit diagram, where Rc is the leakage resistance, Ln is the parasitic inductance, and Rn is the loss resistance caused by other reasons.

电容等效电路图

　　铝电解电容在频率高于一定条件时候机会发生谐振，在这之前呈现容性，超过这个频率就会呈现感性，因此在我们实际电路，如果频率不高的话，一般是工作频率小于电容自身谐振频率的1/10，这时候我们可以忽略电容的寄生效应对电路的影响。

　　When the frequency of aluminum electrolytic capacitor is higher than a certain condition, it will resonate. Before that, it will be capacitive. If the frequency is higher than this frequency, it will be inductive. Therefore, in our actual circuit, if the frequency is not high, the operating frequency is generally less than 1/10 of the resonant frequency of the capacitor itself. At this time, we can ignore the parasitic effect of the capacitor on the circuit.

电容阻抗特性曲线图

　　2.高频电解电容

　　High frequency electrolytic capacitor

　　高频电解电容是相对于普通的电解电容来说，顾名思义这种电容适合于高频场合，高频电容容量一般不能做到与普通的电解容量那么大，高频电容适合于在频率较高的电路，例如开关电源的滤波，在开关电源中的输出滤波电解电容器，其输出电压频率高达数十kHz，甚至数十MHz，对于普通电解电容，在这个频率下早就呈现感性，但是高频电容却能起到很好的滤波作用。

　　High frequency electrolytic capacitor is relative to ordinary electrolytic capacitor. As its name implies, it is suitable for high frequency occasions. In general, the capacity of high-frequency capacitor cannot be as large as that of ordinary electrolytic capacitor. High frequency capacitor is suitable for circuits with high frequency, such as switching power supply filtering. The output filtering electrolytic capacitor in switching power supply has an output voltage frequency of tens of kHz, even tens of MHz. For ordinary electrolytic capacitor, At this frequency, it has long been perceptual, but high-frequency capacitors can play a very good filtering role.