Capacitance Filter & Inductance filter principle

Rectifier circuit output voltage is not the perfect DC, from the oscilloscope to observe the output of the rectifier circuit, you can see the pulse of the pressure components, this is the ripple. In order to obtain the ideal DC voltage, a filter circuit is needed.

Inductors, capacitors, and resistors are often used in filter circuits. Inductance and capacitance of which are energy-storing reactive components, meaning capacitance capacitance to different frequencies of the signal has a different reactance, and a sense of resistance to all the frequency of the signal has the same resistance. The ripple has the characteristic of AC, so the capacitance and inductance have different reactance with the resistance. The higher the capacitance to the more frequency signal resistance, the higher the inductance to the higher the resistance of the signal. The essence of the filter circuit is to construct this circuit network, so that the output of this circuit is less than the communication component.

Capacitor filter circuit, capacitance and load in parallel, capacitance to AC signal resistance than load, so the AC ripple more "like to go" capacitor C1 this road, natural, RL at both ends of the ripple voltage is small, a certain program to achieve the effect of filtering.

As a typical rc-π type filter circuit, it is obtained by adding an RC circuit on the basis of the C-type filter circuit and outputting from the capacitance C2. In front of the analysis, the C1 parallel with the branch of the RC2 circuit that the ripple voltage is reduced, in this RC2, resistance R and capacitance C2 to the AC voltage divider, C2 to the AC signal resistance is smaller, so the sub-pressure is small, that is, the ripple voltage on the C2 is smaller than the R, which further reduces the ripple voltage on the RL, The filtering effect is better than the C-type filter circuit.

For the LC inductance filter circuit, the higher the capacitance to the frequency of the signal resistance, the higher the inductance to the higher the resistance of the signal, so by the split pressure, the C1 on the ripple voltage is smaller.

For π-type or CLC filter circuit, most of the same ripple from C1, a small number of l1c2 walk, and C2 reactance is smaller than L1, so C2 on the ripple is smaller, from the C2 output is reasonable.

It should be noted that the capacitance and inductance is a storage element, the inductance of the AC signal obtained by the sub-pressure, but not consumed, but rather storage, the AC signal is more easily through the capacitor, but the capacitor is also the storage of these energy more. The energy of the inductor capacitor is stored in the circuit when it needs to be released properly, play a role in smoothing.

Capacitance Filter & Inductance filter principle