07-01-2011, 03:42 PM
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INTRODUCTION
Boost converter is one of the most popular choices for high-quality rectification. The converter is supplied from a full-wave rectified line voltage and operated so that the input current follows the input voltage. The input current shaping can be achieved using a number of techniques. When the converter is operated at fixed frequency and fixed duty ratio in the discontinuous conduction mode (DCM), the low- frequency component of the input current is approximately proportional to the input voltage, so that the power factor is automatically close to one. Active control methods include many alternatives, such as constant-frequency peak current control, average current control, and operation at the boundary between the continuous and the discontinuous conduction mode. All of these control methods are now supported by dedicated integrated circuits. Near-unity power factor and almost zero harmonic distortion can be readily obtained.
DIODE RECTIFIERS
INTRODUCTION:
A device that converts ac power into dc power at desired output voltage is called a rectifier. Some industrial applications of rectifiers are UPS for computers, ac motor drives, HVDC transmission lines etc.