Who knows how to model a brushless dc motor?  Can I use a synchronous machine and some circuits? Brushless dc motors do require rotor position information in order to select the appropriate commutation angle. Using three Hall sensors? But how to model a hall sensor or something which can specify the rotor's position and send out a signal? I am looking forward to your answer. If you have some experiences of modeling a double closed-loop dc machine using maplesim, please tell me too.

"User-selection of 

hello,everyone,who can introduce the use of "free motion" component?