Function of filter capacitor

The function of electrolytic capacitor is to filter out the low frequency signal in the current, but even if it is low frequency signal, its frequency is divided into several orders of magnitude. Therefore, in order to be suitable for use at different frequencies, electrolytic capacitors are also divided into high-frequency capacitors and low-frequency capacitors (where high-frequency is relatively speaking).

The low-frequency filter capacitor is mainly used for the electric filter or the filter after the transformer rectifier, and its working frequency is 50Hz in line with the mains power; while the high-frequency filter capacitor is mainly used for the filter after the switching power supply rectifier, and its working frequency is thousands of Hz to tens of thousands of HZ. When we use the low-frequency filter capacitor in the high-frequency circuit, because the low-frequency filter capacitor has poor high-frequency characteristics, it has a large internal resistance and a high equivalent inductance in the high-frequency charging and discharging. Therefore, in use, it will generate more heat due to frequent polarization of electrolyte. The higher temperature will make the electrolyte inside the capacitor vaporize, and the pressure inside the capacitor will increase, which will eventually lead to the bulge and burst of the capacitor.