An induction motor speed control apparatus and method wherein various capacitors are switched in series with the auxiliary winding of an induction motor and, during such switching, the power source is disconnected from the main and auxiliary windings and the in-use capacitors are momentarily connected...http://www.google.com/patents/US5300871?utm_source=gb-gplus-sharePatent US5300871 - Dual capacitor speed control apparatus and method for electric motor
