Inductance filter circuit of the basic role and application occasions

2016-12-06 16:20:10 Source:Shenzhen Yininz technology co., LTD    Author:Admin    Visit:189
The basic role of the inductor in the circuit: filtering, oscillation, delay, notch, etc., the image statement: "through DC, blocking communication"
Refined explanation: In the electronic circuit, the inductance coil on the role of AC limited flow, and resistors or capacitors can be composed of high-pass or low-pass filter, phase-shifting circuit and resonant circuit; transformer can be AC-coupled, Flow and impedance transformation.
By the inductive reactance XL = 2πfL know, the greater the inductance L, the higher the frequency f, the greater the inductive reactance. The voltage across the inductor and inductance L is proportional to the size, but also with the current change speed △ i / △ t is proportional to the relationship can also be expressed as follows: U = LdI / dt as long as the inductance L is large enough, even if the rectifier The output voltage is low to 0, the inductor is still forward current, and to maintain a certain forward voltage on the load.
Inductor coil is also an energy storage element, it is stored in the form of magnetic energy, the size of the stored energy can be expressed as follows: WL = 1/2 Li2. Can be seen, the greater the coil inductance, the greater the flow, the more energy stored.
Check the inductance of good or bad method: inductance measuring instrument to measure the inductance; with a multimeter to measure its off, the ideal inductance resistance is very small, almost zero.
Second, the use of inductors occasions
In the case of a large current, the load resistance RL is small. If the use of capacitive filter circuit, the capacitance is bound to great, and the rectifier diode surge current is also very large, in this case should be used inductor filter.
As shown in the figure below, since the inductance of the induction coil is large enough, it is generally necessary to use a coil having an iron core.
Third, the filter circuit works
As the current flowing through the inductor changes, the induced electromotive force generated in the inductor coil will prevent the current from changing. When the current through the inductor coil increases, the inductance coil of self-induced electromotive force and current direction of the opposite, to prevent the current increase, while part of the energy into a magnetic field can be stored in the inductor; when the current through the inductor coil decreases, Self-induced electromotive force and current direction of the same, to prevent the current reduction, while the release of stored energy to compensate for current reduction. Therefore, the inductance filter, not only the load current and voltage pulsation decreases, the waveform becomes smooth, and the rectifier diode conduction angle increases.