Brushless dc Motors in Medical Applications

Just What the Doctor Ordered: Brushless-dc Motors Brushless-dc motors are taking center stage in medical-equipment design because they last twice as long a competing technologies. • Sensorless brushless-dc-drives have evolved to a point where they have wide appeal within the medical-design community. One reason: A life expectancy of 10,000 hr compared to a brushed motor life of 2,000 to 5,000 hr. • As an alternative to stepper motors, the top seed of BLDC motors is not limited by a large number of poles. Article: Power and efficiency drive motor selection, Article: Selecting dc brush and brushless motors, It used to be that brushless-dc (BLDC) motors just weren't an option for most medical applications. But that situation is changing as the cost of BLDC drive electronics falls. Furthermore, a quest for more-efficient, compact, and reliable medical equipment has put BLDC motors on the prescription list for a variety of applications. By definition, a brushless-dc motor is a synchronous electric motor powered by a dc-power source. While derived from the brushed-dc motor, an electronic commutation circuit takes the place of the standard commutator and brush assembly. In terms of design, though, BLDC and brushed-dc motors are almost direct opposites. The windings of a brushed-dc motor wind around the motor's rotating shaft or armature, whereas the windings of a BLDC motor are affixed to the motor housing. Likewise, the magnets of a brushed-dc motor attach to the motor housing. But the magnets of a BLDC