Overview of filter circuit for DC regulated power supply
Composition and working principle of regulated power supply
(1) The DC stabilized power supply is generally composed of four parts: transformer, rectifier circuit, filter circuit and voltage stabilizer circuit.
(2) Rectification is to use the unidirectional conductivity of diodes to convert alternating current into pulsating direct current. According to the output waveform, rectification can be divided into half-wave and full-wave rectification. Half-wave rectification only needs one diode, but the output is only half of the sine wave, and the conversion efficiency is low. The output of the bridge full-wave rectifier is two half-cycle waveforms, the output voltage is doubled, but the number of rectifier diodes is increased to four, and the circuit is more complicated.
(3) The filter circuit can filter out the AC component in the rectified output to obtain a relatively smooth DC. The average value of the output voltage increases after adding capacitor filtering. Capacitor filtering is suitable for occasions where the load resistance is large and the load current is small. When capacitive filtering cannot meet the requirements, a secondary filter can be added to form a compound filter.
(4) The voltage stabilizing circuit can basically stabilize the output voltage through the automatic adjustment of the voltage stabilizing device when the grid voltage fluctuates or the load changes. Transistor series voltage stabilizing circuit is composed of sampling, reference voltage, comparison and amplification, and adjustment. It has good voltage stabilizing characteristics and is a circuit commonly used at present. Due to the advantages of small size, light weight, and convenient installation and debugging, integrated voltage regulator circuits have been more and more widely used.
(5) The integrated voltage stabilizer has only three terminals of input terminal, output terminal and common terminal, which is easy to use and has good voltage stability.
