Brushless Motors

Brushless motors are synchronous electric motors that have a magnetically (AC induction) or electronically (DC) controlled commutation system instead of a brush-based mechanical commutation system. Brushed motors are used in many applications, but have an important disadvantage in that the brushes wear out. Brushed motors also limit the speed of the motor, and the sparking from making and breaking connections creates electrical noise. In addition, the position of the electromagnet on the armature makes the motor difficult to cool. Brushless motors overcome these limitations because there are no brushes to wear out and there is no sparking. In addition, the electromagnets on the stator are easier to cool. Brushless motors are more efficient, but also more expensive. 

Brushless motors differ in terms of motor type and phase. There are three choices for motor type: AC, DC, and stepper. Brushless DC motors are used most often in variable speed and torque applications. Brushless AC motors include both synchronous and induction products. Brushless stepper motors provide incremental motion or steps in response to pulse of current that alternately change the polarity of the stator poles. Brushless step motors do not require feedback, and are used sometimes in “open loop” or no-feedback applications. In terms of phase, brushless motors include both single-phase motors and three-phase motors. Single-phase brushless motors are used in residential applications whereas three-phase brushless motors are designed for industrial use.  

Motor construction is an important specification to consider when specifying brushless motors. Choices include permanent magnet, shunt wound, series wound, and compound wound. Brushless motors with permanent magnets exhibit constant speed with varying load (zero slip). Shunt wound brushless motors exhibit minimum speed variation through load range and can be configured for constant horsepower over an adjustable speed range. Series wound brushless motors exhibit high starting torques for permanently attached loads. Compound wound brushless motors are designed with both a series and shunt field winding.  

Disc armature brushless motors and coreless or slotless brushless motors are available from some motor suppliers. Disc armatures are flat, pancake-shaped rotors that are driven by an axially, rather than radially-aligned magnetic field.  The thin construction of these armatures can result in low inertia with resulting high acceleration. Coreless and slotless brushless motors incorporate a cylindrical winding that is physically outside of a set of permanent magnets. 

• Reducing cogging torque in brushless motors
  Brushless dc motor windings are similar to the windings in a multiple-phase ac motor. But brushless motors also contain a permanent --magnet rotor and a sensor to detect the rotor position to produce...
  (read more)
• Adaptive Algorithm Stops Cogging in Brushless Motors
  High-performance motion-control applications commonly use three-phase permanent-magnet synchronous motors, popularly known as brushless motors. These motors are typically operated by servodrives that...
  (read more)
• Selecting Dc Brush and Brushless Motors
  A fundamental understanding of the speed-torque curve it the key to specifying a dc motor that will do everything it needs to do. Much has been written about the process of selecting motors for...
  (read more)

Pages: 1 - 3 of 556

Part Numbers for Brushless Motors