What is the function of the filter in the circuit?

author: KZ
The function of the filter is to effectively filter the frequency point of a specific frequency in the power line or the frequency other than the frequency point to obtain a power supply signal of a specific frequency, or to eliminate the power supply signal of a specific frequency.
Using this feature of the power filter, a square wave group or complex noise after passing through the power filter can be turned into a sine wave of a specific frequency.
High-power power filters such as Satons, UBS, frequency converters, etc. will generate a large amount of harmonic current. Such filters need to use active power filters (APF). APF can filter out the 2~50th harmonic current.