3 phase ac induction motor speed control
So you want to rotate a motor at nearly three times its rated speed. Depending on how well the motor is built, it will fail immediately or later. 

Then you build a 200W recitifier. This is the standard Diode Bridge, condensator setup. 

And a 200W Pulse width sine generator. The tools for that are listed on Atmels AVR site. They have example code to do just that. You should be able to glean the code from some of the examples on 

http://www.atmel.com/dyn/products/app_notes.asp?family_id=607#Application_Example_and_Algorithms

Wouldnt it be cheaper to get a faster motor in the first place?