# Filter Inductor Principle Of Circuit Action

Filter Inductor Commonly used filter circuit passive filter and active filter two categories. The main forms of passive filtering are capacitive filtering, inductive filtering and complex filtering (including inverted L-type, LC filter, LCπ filter and RCπ filter, etc.). The main form of active filtering is active RC filtering, also known as the electronic filter. The magnitude of the pulsating component in the direct current is expressed by the ripple factor. The larger the value is, the worse the filtering effect of the filter

1. Resistance filter circuit:

Filter Inductor RC-π filter circuit, in essence, is based on the capacitor filter plus a RC filter circuit. Figure 1 (B) RC filter circuit. If S is the voltage across C1

Pulse coefficient, the output voltage at both ends of the pulsation coefficient S = (1 / ωC2R) S. From the analysis we can see that the role of resistance R is the residual ripple voltage drop at both ends of the resistor, and finally by C2 and then bypass off. In the case of a certain value of ω, the greater the R, the larger the C2, the smaller the pulsation factor, that is, the better the filtering effect. And R value increases, the resistance of the DC voltage drop will increase, thus increasing the DC power supply internal loss; if the increase in C2 capacitance, will increase the size and weight of the capacitor, reality. This circuit is generally used when the load current is relatively small.

2. Inductive filter circuit:

Filter Inductor According to the reactive components of the AC and DC impedance of the different, by the capacitance C and inductance L composed of the basic form of the filter circuit shown in Figure 1. Since the capacitor C is open to DC and has a small AC impedance, C is connected in parallel at both ends of the load. Inductor L is small for DC impedance, large for AC impedance, so L should be connected in series with load. The parallel capacitor C, when the input voltage rises, charges the capacitor and stores part of the energy in the capacitor. And when the input voltage decreases, the capacitor voltage across the exponential discharge, you can put the stored energy released. After the filter circuit to the load discharge, the load on the output voltage is relatively smooth, played a smooth effect. If the inductor filter is used, when the input voltage increases, the current in the inductor L connected in series with the load increases, so the inductance L will store part of the magnetic field energy, and when the current decreases, the energy is released and the load current becomes smooth. , Inductance L also has a wave effect.

Filter Inductor The use of energy storage components inductor L can not change the current characteristics of the rectifier circuit load loop in series with an inductor, the output current waveform is more smooth. Because the inductance of the DC impedance is small, the impedance of the exchange, so you can get a better filtering effect and DC loss is small. Inductive filter is the disadvantage of large size, high cost. Bridge rectifier inductance filter circuit shown in Figure 2. The waveform of the inductor filter is shown in Fig. According to the characteristics of the inductor, when the output current changes, L will induce a back EMF, so that the rectifier conductive angle increases, the direction will prevent the current changes.