Three phase AC-DC power converters are vastly applied in industrial applications to remove low frequency harmonic from current absorbed from utility grid. ecause of simpler structure and lower cost, discontinues mode converter are better option respect continuous mode converters for lower power applications (below 6kw). At first a DCM SEPIC converter with very low input current THD is introduced. The proposed converter can absorb continuous currents with very low THD from utility grid over wide ranges of input voltage and output power. In two switch SEPIC converter voltage stress and number of magnetic switches of first converter are reduced. Although very low THD can be achieved by SEPIC converter but its efficiency is lower that boost converter. In a new introduced boost converter THD and input current ripple of boost is improved. PFC converter commonly follower by a dc-dc converter for isolation and regulation purpose. A single stage converter with very input current THD and controlled intermediate bus voltage is also proposed. Single stare converter due high switching losses hasn't high efficiency, so a new two stage boost-full bridge configuration AC-DC converter with very low THD and high efficiency is introduced. Keywords: Three phase AC –DC converter, three phase rectifier, Power factor correction.
