How to choose active power filter?

1. In order to meet the requirements of the working frequency of the load circuit and the frequency to be suppressed, if the frequency to be suppressed is very close to the useful signal frequency, a filter with very steep frequency characteristics is required to filter out the suppressed interference frequency, and only the requirements of passing through the useful frequency signal are allowed.

2. The power filter shall have sufficient mechanical strength, simple structure, light weight, small volume, convenient installation, safety and reliability.

3. For APF manufacturers, the APF must have a certain withstand voltage capability. The power filter should be selected according to the rated voltage of power supply and interference source, so that it has a high enough rated voltage to ensure that it can work reliably under all expected working conditions and can withstand the impact of input instantaneous high voltage.

4. It is required that EMI filter can meet the attenuation characteristics and insertion loss requirements of load requirements within the corresponding working frequency band. If the attenuation of a filter cannot meet the requirements, multi-level coupling can be used to obtain higher attenuation than single level. Different filter level coupling can obtain good attenuation characteristics and insertion loss in wide frequency band.

5. The power filter is allowed to pass through the rated current which shall be consistent with the continuous operation in the circuit. If the constant current is high, the volume and weight of EMI filter will be increased; if the constant current is low, the reliability of EMI filter will be reduced.

6. At the required frequency, the impedance of the EMI filter RFI filter must match the impedance of the interference source and the load to which it is connected. If the load is high impedance, the output impedance of the power filter shall be low impedance; if the power or interference source impedance is low impedance, the output impedance of the filter shall be high impedance; if the power or interference source impedance is unknown or is in It is difficult to get stable filter characteristics for a large range of changes. In order to get good and stable filter characteristics, we can connect a fixed resistance at the input and output of the filter.