Brushless Servo Motors

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Brushless Servo Motors: An introduction to our high-performing motors

Precise torque, speed, and position control are hallmarks of brushless servo motors

The high torque-to-weight ratio and flexible design make them ideally suited for use in a broad range of demanding and highly dynamic applications that require adherence to trajectories as well as quick positioning and precision. Among the wide range of applications that benefit from servo motion control are robotics, actuation systems, pick-and-place equipment, semiconductor fabrication, test and packaging equipment, machine tool axes, and more.   
Introducing the Infranor series of brushless servo motors  
The Infranor line of brushless servo motors builds on our 50 years of experience in design and manufacturing. Our extensive product and application know-how, engineering skills, sourcing, and in-house flexible manufacturing has earned the trust and business of well-known machine builders in a variety of industries across the world. 

Tailored and implemented in close technical collaboration with the customer, Infranor’s latest brushless servo motors include slotless, segmented, skewed, and high-pole torque ring stator designs. 

Let’s take a look at the defining characteristics of each product series:

  • The FP series of motors utilizes a slotless design that eliminates the traditional winding teeth. It yields the highest torque at speed, zero cogging, and very high efficiency. These motors can be more costly to produce but provide premium attributes.
  • The N series of motors features a low cogging segmented stator design. It yields high torque at typical operating speeds, and is very torque-dense and cost-effective.
  • The T series of motors utilizes a skewed stator design that provides enhanced performance, reduced cogging and high dynamic motion. In addition to being cost-effective, this family features more options, including an internal inertia wheel.
  • The BR series utilizes a high-pole count stator design that provides very high torque in a small low-profile package. (Read more about our BR Torque Motor here.)  

A closer look at brushless servo motors  
The central design of modern brushless servo motors features a synchronous machine with permanent magnets on the rotor. These high-performance motors get their speed from the available voltage and their torque from the available current of the servo drive. 

Unlike a brush motor, a brushless motor has no physical commutator or brushes for controlling the magnetic field. This means it requires a feedback device — that’s what the term “servo” refers to — to provide motor position information of the rotor vs. the stator. 

Consider a few motors that are similar, yet do not meet the definition of brushless servo motors.

  • An AC vector motor is also a brushless motor but it lacks permanent magnets and therefore does not boast the same precise control, power density, and efficiency as a brushless servo motor.
  • A stepper motor is a high-pole count brushless motor but it does not require a feedback device and typically cannot achieve very high speeds. 

Over the years, the industrial applications of brushless servo motors have increased significantly. A few factors, in particular, have led to their rise, reports Electrical Engineering Portal:

  • More affordable power conversion products
  • Establishment of advanced control of PWM inverters
  • The emergence of more powerful and user-friendly permanent magnet materials
  • Increased need for highly accurate position control
  • Proliferation of all these components in a very compact form 

How brushless servo motors evolved  

Brushless servo motors emerged to solve an issue with the early version of servo motors that used brushes to transfer electricity. As the spring-loaded carbon brushes wore out, they left behind debris that interfered with the performance of the motor. The new brushless design emulated the brush-type DC servo motor, but the original lower-cost, longer-lasting motor came with certain drawbacks; for example, it could only be used in low-power applications.  

As innovation picked up pace, brushless servo motors gradually turned into what they are today. Featuring the most advanced magnet technology and the ability to connect to various brushless servo drives, they deliver unmatched performance characteristics. And, as Infranor’s product series shows, development continues unabated to meet the demands of rapidly evolving industries and next-generation machines.

Considering the benefits  

Servo motors are divided into two categories: linear and rotary. Each brings a distinct set of benefits to certain complex applications. 

  • Rotary servo motors are used in many industries including Robotics, Semiconductor Fabrication, Packaging and Food Processing, Flight Simulators, and Metal Forming just to name a few. Benefits include, for instance: 
    • High acceleration
    • Continuous torque out to faster speeds
    • Low Maintenance
    • Extremely efficient 
  • Linear servo motors are used with short-move pick and place and inspection equipment, longer moves and flying shear applications, roller coasters, people movers, and vehicle launching systems. A drawback of linear servo motors is their tendency to heat up, which can lead to thermal growth and reduced component lifespan, according to Automation Engineers. Benefits include:
    • Higher speeds
    • Higher accelerations
    • Direct drive
    • Practically no wear
    • High position accuracy


Just as brushless servo motors helped power the rise of automation, they continue to propel performance-driven industries of today. Do you have questions for us? We combine the best in engineering and design for high-quality production level motors and drives. Our goal is to improve your machine’s performance. Contact us today.