We have already proposed the new control method of the bidirectional isolated DC/DC converter with a current resonant circuit which can perform the zero-current switching and the power factor improvement by means of the pulse width control. This method is that the pulse width of the inverter of the higher d.c. voltage is narrowed to make equal the fundamental a.c. voltage of both inverters. However,in this current resonant circuit, since the reactor becomes large and the resistance increases, there is a problem that the improvement of the efficiency is not so high. In this paper, in order to solve these problems, a new bidirectional isolated dc/dc converter using the NPC 3 level inverter will be proposed.