Hi,
The contributions to this site from Mr. A.M.Bhatt would be a great reference for you.
Here are links to some of his works;
http://www.engineersgarage.com/contribution/ac-motor-speed-controller-using-rf-remote-circuit
http://www.engineersgarage.com/contribution/ambhatt/single-phase-ac-motor-speed-controller
http://www.engineersgarage.com/contribution/ac-motor-speed-controller-using-rf-remote-circuit?page=2