Power DC/DC and AC/DC analysis

Issue Time:2006-08-17
Power can be divided into AC/DC and DC/DC. The DC/DC converter has been modularized, and the design technology and production process have been matured and standardized both at home and abroad and have been recognized by users. However, the modularization of AC/DC is modularized due to its own characteristics. The process encountered more complex technical and process manufacturing problems.

DC/DC conversion
The DC/DC conversion converts a fixed DC voltage into a variable DC voltage, also known as a DC transient. There are two working modes of the transient oscillator. One is that the pulse width modulation mode Ts is unchanged, and the ton is changed (general); the second is the frequency modulation mode, and ton is unchanged. Change Ts (prone to interference), the specific circuit has the following categories:

(1) BUCK circuit A step-down wave oscillator whose output average voltage Vo is smaller than the input voltage Vt and has the same polarity.

(2) The BUCK circuit is a piezoelectric oscillator whose output average voltage v0 is greater or smaller than the input voltage and has the same polarity.

(3) BUCK circuit A voltage or boosting transient device whose output average voltage Vo is greater than or less than the input voltage v0, the polarity is opposite, and the inductance is transmitted.

(4) BUCK circuit A step-down or step-up transformer whose output average voltage v0 is greater or smaller than the input voltage U has the opposite polarity and the capacitance is transmitted.

AC/DC conversion
The AC/DC conversion converts the alternating current into direct current, and its power flow direction can be bidirectional. The power flow flows from the power source, and the load is called “rectifying”. The return of power from the load is called "active inverter." AC/DC converter input is 50/60Hz AC, because it must be rectified and filtered, so the relatively large filter capacitor is essential, and at the same time due to safety standards (such as UI, CCE, etc.) and EMC directives Restrictions (such as IEC, FCC, CSA), the AC input side must be added with EMC rate and use of components that meet safety standards, thus limiting the size of the AC / DC power supply. In addition, due to the internal high-frequency, high-voltage, high-current switching action, it is more difficult to solve the EMC electromagnetic compatibility problem, and it also puts high requirements on the internal high-density installation circuit design. For the same reason, high voltage, high current switching increases many power losses, limiting high requirements. For the same reason, high-voltage, high-current switches increase the operating loss of many power supplies, limiting the modularization process of AC/DC converters. Therefore, power system optimization methods must be adopted to achieve a certain degree of satisfactory work efficiency.

AC/DC conversion can be divided into half-wave circuit and full-wave circuit according to the wiring mode of the circuit. According to the number of power phases, it can be divided into single-phase, three-phase and multi-phase. According to the circuit T, the quadrant is divided into one quadrant, two quadrants and three. Quadrant, four quadrants.

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