Abstract: In an induction motor rotor windings are connected together in a squirrel cage or a wound rotor .DELTA. configuration and stator windings are connected in series across a source. A capacitor is connected in parallel with one of the stator windings and this combination is connected in series with the other stator winding and is sized to form a quasi-double-resonant circuit. Both a single-phase and a polyphase motor can be configured as a quasi-double-resonant circuit with respect to each input power phase. A switching circuit employing compactors allows changing the rotation direction of the motor in a polyphase motor. A further polyphase motor is also described with primary stator windings connected to each power phase input and interleaved secondary stator winding, magnetically coupled to the primary stator windings but not directly connected to the power inputs. The secondary stator windings have capacitors coupled in parallel thereto to form parallel floating resonant circuits.