Working principle of EMI filter
Working principle of EMI filter
Electromagnetic interference (EMI) is broadly defined as electrical or electromagnetic interference that reduces or damages signal integrity or the components and functions of electrical equipment. Electromagnetic interference; These include rf interference, which is usually divided into two broad domains:
Narrowband emissions are usually artificial and limited to a small part of the radio spectrum. The hum emitted by an electrical cable is a good example of narrowband transmission. They can be continuous or sporadic.
Broadband launches can be made in madness or be natural. They tend to affect large areas of the electromagnetic spectrum. They can be random, sporadic or punctual. From lightning to computers, everything produces broadband radiation.
Sources of the ime:
Electromagnetic interference treated by EMI filters can be caused in different ways. Inside the electrical equipment, interference can be caused by the current impedance in the interconnection lines. It can also be produced by voltage variations in the conductors. EMI is generated externally by cosmic energy, for example solar flares, power or telephone lines, electrical appliances and power lines. Much of the electromagnetic disturbance is produced along power lines and transmitted by them to devices. Emi filters can be devices or internal modules designed to reduce or eliminate these types of interference.
Filter for EMI:
Without going further into the hard sciences, most emi are in the high frequency range. It simply means that if a signal is measured, for example a sine wave, the period will be very close. EMI filters have two types of components that work together to suppress these signals: capacitors and inductors.
Capacitors suppress the direct current in which a large amount of electromagnetic interference is introduced into the device, while allowing the passage of alternating current. Inductors are essentially tiny electromagnetic components capable of retaining energy in a magnetic field as current passes through it, reducing the total voltage. Capacitors used in EMI filters, called "shunts", redirect high-frequency currents in a specific range to move them away from circuits or components. Bypass capacitors supply high-frequency currents/interferences into inductors arranged in series. As the current passes through each inductor, the overall current or voltage decreases. Ideally, the inductor reduces interference to zero, also known as a ground short circuit. EMI filters are used in various applications.
