AC DC converter refers to a kind of power equipment that converts alternating current into direct current. Simply speaking, it is a switching power supply. Using PWM principle, MOS tube works to produce a change of waveform and then transforms the voltage through a transformer and then commutates the output. The conversion of alternating current into direct current is called rectification, and the conversion of direct current into alternating current is called contravariant.

The common method of inverter power supply is: the sinusoidal waveform is modulated in SPWM mode, and then the output voltage polarity is switched through an H bridge, which requires the switching of H bridge and SPWM circuit to be synchronized. Technically complex, but high efficiency, many inverters in the market are used in this way.

AC DC converter generally converts alternating current into direct current through diode rectifier circuit or switching circuit. The working process is as follows: mains access - power transformer - rectifier circuit - filter circuit - voltage regulator circuit. Firstly, the alternating current of power frequency is converted to pulsating direct current through rectifier circuit, and then the ac component in pulsating direct current is filtered out through filtering circuit to reduce the AC component and increase the DC component. Finally, the voltage regulator circuit adopts the negative feedback technology to further stabilize the rectified DC voltage.

Rectifier is the main component of the diode, rectifier mode has full - wave rectifier and half - wave rectifier. Full-wave rectifier, also known as bridge rectifier, is commonly used side has a center tapped transformer and two diodes constitute a circuit, so positive and negative half a cycle of current flow through the load, so as to improve the efficiency of rectifier. The half-wave rectifier circuit USES the unidirectional conductivity of the diode to make the voltage coming out of the transformer reach the load only half a cycle. Single-phase bridge rectifier circuit is the most basic circuit to convert alternating current to direct current. The diode in the circuit has unidirectional conductivity.

The functions of power control chip in AC DC converter are: safety isolation, noise isolation, voltage transformation, polarity transformation, ground loop elimination, voltage stabilization, noise reduction, overcurrent, short circuit protection and so on.

Due to the limitations of SAFETY standards such as UL and CCEE and EMC directives such as IEC, FCC and CSA, AC inputs must be filtered by EMC and components conforming to safety standards must be used, so AC-DC converters must be rectified and filtered. At the same time, internal switch actions such as high frequency, high voltage and large current make EMC EMC more difficult and internal high-density circuit design more difficult. The long time and high consumption of power supply limit the modularization process of AC-DC converter.