A power line filter, which is also called an EMI power filter, is a type of electronic filter that is placed between the external power lines and electronic devices. It is used to enable the conductivity of radio frequencies or electromagnetic interference between the AC or DC power line and the equipment. It works as a passive bi-directional electrical equipment that can screen through almost any frequency point in the power line. These types of liner filters are created for electromagnetic interference (EMI) and are a network with two ports that is built up of inductors, capacitors, resistors.
There are three main indicators that need to be discussed when choosing between different power line filters. The first that should be analyzed is the voltage and current, followed by the insertion loss, and the third being the size and structure.
The noise and line filters that come from the electromagnetic interference is a low pass filter that transmits the AC to the source of power without the need to attenuate. It also inhibits the electromagnetic interference noise coming from the power equipment so as to mitigate from it entering the AC power grid to interfere with other electronic devices.
According to the characteristics of EMI at the power port, the EMI noise filter/line filter is a passive low-pass filter, which transmits AC to the power supply without attenuation and greatly attenuates the EMI noise incoming with AC. At the same time, it effectively suppresses EMI noise generated by power equipment, to prevent them from entering the AC power grid to interfere with other electronic devices.
The power line filter's principle refers to the principle that states that the bigger the impedance or interruption that mismatches with the filter output and input as well as with the load & power side, the more likely the electromagnetic interference is attenuated. The way that this works is as follows: after the diode rectifies the AC, the current intensity is ever changing despite a single current direction. Filtering would have to be implemented in order for the ripple DC to become a smooth waveform. The objective here is to limit the degree of ripples in the output voltage of the rectifier as much as is possible and convert it to the nearest constant DC.
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