ORIGINAL: guru101
You will need to buy a brushless ESC if you want to change to a brushless motor, brushed motors are DC current and brushless are AC with electronic timing handled by the ESC.
Brushless motors are DC not AC. The ESC is what modulates the voltage to act like AC voltage. The end result is a modified sine wave (a mix between a square and sine wave). It's switched by the MOSFETS in the ESC which turns the motor.