How to correctly select a filter capacitor for the purpose of adding a filter capacitor to the power supply?

A filter capacitor is an energy storage device installed on both sides of a rectifier circuit to reduce AC pulse ripple index and improve efficiency, smoothness, and DC output. Because the filtering circuit specifies a large capacity of energy storage capacitors. High frequency filter capacitors mainly work in the filters after rectification of switching power supplies, with output power ranging from over 1000 Hz to tens of thousands of Hz. Generally, low-frequency Electrolytic capacitor gradually generates inductance at 10000 Hz, which cannot meet the needs of switching power supply. Generally, low-frequency Electrolytic capacitor gradually generates inductance at 10000 Hz, which cannot meet the needs of switching power supply.

A general understanding of capacitor types is beneficial for quickly selecting capacitor types. There are many kinds of capacitors, including chip capacitors and plug-in capacitors according to packaging, Ceramic capacitor, tantalum capacitors, Electrolytic capacitor, mica capacitors and film capacitors according to materials, and BU2092FV-E2 is divided into fixed capacitors, semi fixed capacitors and variable capacitors. There are various types of capacitors that are prone to syndrome, but there is no need to worry. Ceramic capacitor, Electrolytic capacitor and tantalum capacitor are widely used in switching power supply. After mastering the type of capacitor, master the performance parameters of the capacitor.

Only by mastering the basic key parameters of capacitors can they be quickly selected and reliably applied. The key parameters of capacitors are all the same, including capacitance value, compressive value, capacitor ESR, allowable capacitance accuracy, and operating temperature range. In the design of switching power supply, the most commonly used capacitors are Ceramic capacitor, Electrolytic capacitor and tantalum capacitors. Ceramic capacitor has small capacitance, good high-frequency characteristics, wide operating temperature range, smaller ESR than Electrolytic capacitor, small volume, large capacity of non-polar Electrolytic capacitor, but narrow operating temperature range, large ESR, minimum ESR of tantalum capacitor, larger polarity than Ceramic capacitor, and poor safety performance.

The usage scenarios of capacitors can also be divided into internal circuit environment and external circuit environment. The internal circuit environment includes frequency, voltage value, current value, and the main role of capacitors in the circuit. The type of capacitor can be determined based on the circuit frequency. Based on the voltage value, the withstand voltage value of the selected capacitor can be determined. According to the external usage scenario of the power supply, the selection of capacitors, the working temperature of the product, safety regulations, etc., the main functions of the circuit can refer to the capacitors of the selected capacitors. Suitable for reducing the selection range of capacitors. Improper selection of capacitors can cause slurry explosion and electrolyte drying during use, ultimately leading to power failure.

Filter capacitors are used for power rectification circuits and filtering AC. Make the exported DC smoother. For precision circuits, parallel capacitor circuit combinations are usually used to improve the working efficiency of filter capacitors. Low frequency filter capacitors are mainly used for voltage filtering or transformer rectification filtering, and their operating frequency is consistent with the voltage at 50Hz. The high-frequency filter capacitor mainly operates in the filter after rectification of the switching power supply, with an output power ranging from 1000Hz to tens of thousands of Hz.

How to choose filter capacitors correctly? Especially the export of filter capacitors is a matter of great concern for every engineer. Generally, Electrolytic capacitor used for 50Hz DC power supply has a pulsating voltage frequency of only 100Hz and a charging and discharging time of milliseconds. In order to obtain a smaller pulse index, the required volume reaches hundreds of thousands of microfacies. Therefore, the purpose of low-frequency Aluminum electrolytic capacitor is to improve its capacity, and the capacitance, tangent of consumption angle and leakage current of the capacitor are the basic parameters to distinguish its quality. The sawtooth voltage frequency of filtered Electrolytic capacitor derived from switching power supply can reach tens of thousands of HZ or even tens of MHz. At this time, capacitor is not its key indicator. The standard for considering the quality of high-frequency Aluminum electrolytic capacitor is the characteristics of impedance frequency. It is specified to have a lower equivalent impedance at the operating frequency of the switching power supply, which has a good filtering effect on the high-frequency peak signal generated during the operation of semiconductor equipment.

Generally speaking, low-frequency Electrolytic capacitor gradually generates inductance at 10000 Hz, which cannot meet the needs of switching power supply. High frequency Aluminum electrolytic capacitor for switching power supply has four terminals. The two sides of the positive aluminum plate are respectively led out as positive stages of the capacitor, and the two sides of the negative aluminum plate are also led out as negative stages. Current flows into one end of a four terminal capacitor. According to the capacitor, the current flowing into the load from the other end also flows out from one end of the capacitor and into one end of the power supply from the other end.

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