The merits and the operation methods of a current source Inverter, in a induction motor drive, are fully discussed. With the constant flux and the constant slip frequency operation, large starting torque and low starting current states are obtained. In a no load state, controlling a slip has a power factor improvement and a power save. And, a new designed 12 step current source Inverter is introduced. In order to block the rotating current caused by the E.M.F.(electromotive force), autotransformers are used. In a appendix, inductor design methods are described.