connected to the boost converter 17 the control circuit 19 is connected to the three phase power supply 11 one terminal of the output current sampler 18 the bi direction switches 15 and the boost converter 17 the other terminal of the output current sampler 18 is connected to the outputs 14 as far as the current gaps between u00b1 u03c0 6 interval in the primary rectifier i is concerned in the 12 steps in the feed forward compensation circuit ii the control circuit 19 makes the bi direction switches 15 cut off the control circuit 19 makes the bi direction switches 15 cut off the phase c in a b interval the phase a in b c interval the phase b in c d interval the phase c in d e interval the phase a in e f interval the phase b in f g interval the phase c in g h that is for the two phases at same polarity the phase with higher absolute value is cut off by the bi direction switches 15 then the phase with lower absolute value is forced to conduct to the third phase such as the phase a with phase b in a b interval the phase c with phase b in b c interval the phase c with phase a in c d interval the phase b with phase a in d e interval the phase b with phase c in e f interval the phase a with phase c in f g interval the phase a with phase b in g h so as to generate a dc voltage through the rectifier 16 of the feed forward compensation circuit ii then the boost converter 17 forces the output dc current of rectifier.