Torque motors vs Conventional servo motors

Different motor types are used to provide rotary motion within industrial applications. Each application has different requirements for speed, torque and accuracy, as well as its constraints in build-in volume and budget. This page briefly introduces different types of motors and their performance in positioning/indexing applications. Please watch our webinar recording to find out more in-depth information.

 

Motors for industrial automation

Motors types overview

Torque Comparison Overview Cut

DC motors

DC motors operate by supplying coils on the rotor with DC current and  have internal commutation by brushes to ensure correct rotation.  The brushes have a limited lifetime and can generate acoustic and electrical noise. Its characters make the motors easy to control, but comes with limited performance.

Operating Principle

 

Ac Motor Operating Principle

AC motors

AC motors, particularly the three-phase type, operate by feeding power to the stator to generate a rotating magnetic field. Commonly used in high-power applications without the need for precise positioning. AC motors can be operated with and without a controller. This flexibility makes it the most common motor throughout general industry, yet, the higher losses and higher reaction time makes them less suited for precision application.

 

Stepper motors

Stepper motors make discrete steps allowing for position tasks without an encoder. They are well-suited for low-speed, open-loop positioning applications where cost-effective solution is required. However, stepper motors have drawbacks, including being noisy and the accuracy is limited to the number of steps per revolution.

Stepper
Conventional Servo Motor

 

Conventional servo motors

Conventional servo motors are designed to run with an encoder in mind, while this configuration incurs higher costs, it delivers an extensive range of speeds and torques, ensuring precise positioning.  They are well-suited for applications demanding high-speed and dynamic performance, particularly in scenarios requiring accurate and controlled positioning.

 

Torque motors

Torque motors, often referred to as direct drive or frameless motors, operate on a principle similar to permanent magnet synchronous servo motors and are commonly employed with servo-loop control. Distinguished by their direct drive design, these motors are specifically crafted for applications requiring high torque and lower speeds. Their niche lies in low-speed, high-torque scenarios where precise positioning is crucial. Synonyms such as direct drive motor and frameless motor highlight their distinctive features and usage, emphasizing their significance in situations demanding accurate positioning and robust torque capabilities.

Qtl 310 85 Explodedview

Integrating into application

Conventional servo motors

  • Smaller diameter, higher speed, lower torque
  • Transmission is required
  • Shaft output requires coupling to connect to gearbox
  • Separated frame, with bearings & encoder
Conventional Motors

Torque motors

  • Larger diameter, lower speed, higher torque
  • No transmission is required
  • Large diameter rotor
  • Frameless design, can be integrated in machine frame in application
Torque

 

Performance

Conventional servo motors

  • Coupling & gearbox required
  • Lost motion
  • Backlash
  • Compliance
  • Longer settling time, lower accuracy

Torque motors

  • Direct connection between motor and load
  • Shorter settling time, better accuracy

We carefully compared stepper motors, conventional servo motors, and torque motors across various parameters such as motor speed, indexing speed, accuracy, applicable applications, initial costs, and total cost of ownership. To gain a comprehensive understanding of the advantages and disadvantages associated with these motors, we encourage you to watch the webinar. Discover the best motor solution for your specific application needs.

 

For more information, please watch our webinar recording below.

In this webinar, we compared conventional servo motors and direct drive torque motors. These motor types are often used in demanding applications where fast and precise movements are required. We will cover the characteristics of each motor type and how they impact the performance of the applications.

Watch Webinar recording

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