Tesla applied for US patents in October and November 1887 and was granted some of these patents in May 1888. The first AC commutator-free polyphase induction motors were independently invented by Galileo Ferraris and Nikola Tesla, a working motor model having been demonstrated by the former in 1885 and by the latter in 1887. The first commutator-free single-phase AC induction motor was invented by Hungarian engineer OttГі BlГЎthy he used the single-phase motor to propel his invention, the electricity meter. By manually turning switches on and off, Walter Baily demonstrated this in 1879, effectively the first primitive induction motor. In 1824, the French physicist FranГ§ois Arago formulated the existence of rotating magnetic fields, termed Arago's rotations. Squirrel-cage rotor construction, showing only the center three laminations

Squirrel-cage induction motors are very widely used in both fixed-speed and variable-frequency drive applications. VFDs offer especially important energy savings opportunities for existing and prospective induction motors in variable-torque centrifugal fan, pump and compressor load applications. Although traditionally used in fixed-speed service, induction motors are increasingly being used with variable-frequency drives (VFD) in variable-speed service. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans.

Three-phase squirrel-cage induction motors are widely used as industrial drives because they are self-starting, reliable and economical. An induction motor's rotor can be either wound type or squirrel-cage type. An induction motor can therefore be made without electrical connections to the rotor. Many such motors have a symmetric armature, and the frame may be reversed to place the electrical connection box (not shown) on the opposite side.ДЄn induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. Cutaway view through stator of TEFC induction motor, showing rotor with internal air circulation vanes.

Motor winding machine manufacturers