NiSh:
There is a good book that may help and most likely is in your school library already.
Electrical Motor Controls: Automated Industrial Systems 3rd Edition; Rockis; American Technical Publishers; 92, Electrical Control for Machines: 5th Edition; Rexford; Delmar Publishers; 97
This has been the best book so far in explaining Constant Voltage Transformers. I did a search through google and came up with jillions of hits as well, subject was definition constant voltage transformer.
Hope this helps, but the book is a real winner here.