ABSTRACT
Accurate and ripple-free torque control of electric motors is essential to precision motion control, with a huge range of applications: from siliconwafermanufacturers,medical, robotics and automation industries
“73605_C023” — #2
to themilitary. Permanent-magnet synchronousmotors, also known as brushless DC (BLDC)motors, are commonly used as the drives of servo systems. BLDC motors are composed of a rotor containing a series of permanent magnets and the armature which remains static while the electric power is distributed by an electronically controlled commutation system, instead of amechanical commutator using brushes. BLDC motors offer several advantages over brushed DC motors making them suitable for use as servomotors. These include higher efficiency and longer lifetime because of the absence of electrical and friction losses as well as erosion due to brushes, and reduction of electromagnetic interference and noise because of elimination of ionizing sparks from the brushes. Moreover, BLDC motors can deliver more power per mass compared to their cousin DC motors because the stator windings attached to the BLDC motor’s housing can be cooled effectively through conduction whereas DC motors with windings on the rotor dissipate heat mainly by convention, typically by a cooling fan inside the motor. This also means that BLDC motors can be completely sealed off and protected from dirt, oil, grease, and other types of foreign matter.
