Induction motor switchable between series delta and parallel wye

An induction motor comprising:

• a single rotor formed in one-piece having a first and a second rotor core axially mounted on a common axis with an airspace or a non-magnetic portion being provided between said two rotor cores and having on said two rotor cores a plurality of rotor conductive members extending therethrough;
• a first and a second stator disposed side by side and surroundingly facing said respective rotor cores, said first and second stators having a first and a second stator core on which a plurality of polyphase windings are being wound, said plurality of polyphase windings of said first and second stators being interconnected so as to form a series .DELTA.-connection;
• and
• a phase changing means having short-circuiting switches disposed respectively between series-junction nodes of said respective stator windings of different phases of said first and second stators, for varying the phase difference between the rotational magnetic fields around said first rotor core generated by said first stator and the rotational magnetic fields around said second rotor core generated by said second stator by the operation of said short-circuiting switches.