Every application relies on a correct choice of the system parameters which must be clearly defined in order to exploit at the best the remarkable features of the modern brushless drives which often are not fully understood. The variety of selection originates from the fact that a brushless motor can not be hardly considered as a simple motor, but recognised as complex drive system incorporating an elaborated reverse action degree making it much more flexible and sophisticated.
In fact, the brushless motor is, from the conceptual point of view, more similar to the membrane of a loudspeaker than to a conventional motor; it can reply very rapidly to any electric control but, as for the loudspeakers, the quality of the result will depend much more on the control system than on the piece itself.
The project manager who decides to install a brushless motor, is forced to make some choices for the study of the system both on the mechanical and electronic point of view; in order to opt for the best opportunity, a deep knowledge of the operation principles and of the wide possibility offered by the modern brushless drives is therefore indispensable.
In particular, the fundamental choices recurring in every system are the following:

• at a mechanic level: choice of the method of transmission, of the gear ratio, of the conversion type of the motion, of the clutches and the couplings;
• at an electronic level: choice of the feedback action strategy, of the type and number of the sensors and their arrangement, of the control and synchronization equipment, of the transmission method of the controls.

The following chapters contain some useful hints as s support for the choice according to the application.

• Introduction
• Choice of the most suitable transmission and drive
• Operating Principles, peculiarity and restrictions
• Choice of the method of transmission
• Choice of the back-drive method
• Check of the Dimension of the Motor and the Electr
• Limits peculiar to the motor