How to Select an Inrunner PMSM Torque Motor

Selecting the right frameless inrunner PMSM torque motor is essential for achieving the desired performance, efficiency, and reliability of your machine. Whether you are designing a robotic joint, a high tech handling system, medical device, or industrial automation platform, choosing the correct motor requires more than simply looking at torque values.

At Magnetic Innovations, we help engineers select direct drive motors based on application requirements, available installation space, performance targets, and environmental conditions. Our Série IR-F of frameless inrunner PMSM motors covers a wide range of applications, from compact precision systems to demanding industrial machinery.

Step 1: Define the Required Torque

Torque is typically the starting point for motor selection.

When evaluating an inrunner PMSM Torque Motor, both continuous torque and peak torque should be specified. Continuous torque represents the torque required during normal operation, while peak torque defines the short-duration torque needed during acceleration, deceleration, or temporary overload conditions.

For example:

  • Continuous torque: 4 Nm
  • Peak torque: 8 Nm for 2 seconds

Choosing a motor based solely on peak torque may lead to overheating, while selecting only on continuous torque may limit machine performance.

Typical IR-F Inrunner PMSM Torque Motor Ranges

Series Continuous Torque Range Peak Torque Range Outer Diameter
IR-F 52 0.22 – 0.97 Nm 0.49 – 1.44 Nm 52 mm
IR-F 85 1.3 – 6.4 Nm 3.5 – 7.9 Nm 85 mm
IR-F 170 11.6 – 56.2 Nm 31 – 70 Nm 170 mm

What if I Don’t Know the Required Torque?

Many engineers are familiar with specifying motor power (kW) and speed (rpm), but not necessarily torque. This is especially common when replacing a conventional motor and gearbox combination with a direct drive solution.

Torque is the rotational force produced by the motor and is often the most important parameter when selecting a frameless PMSM torque motor. In many applications, the required torque can be calculated from the existing system’s power and speed requirements.

Converting Power and Speed to Torque

When replacing a traditional motor and gearbox, the required torque can often be estimated from the available power and operating speed.

Torque (Nm) = (9550 × Power (kW)) ÷ Speed (rpm)

For example, a 1 kW motor operating at 2,000 rpm generates approximately 4.8 Nm of torque (Torque = (9550 × 1) / 2000 = 4.8 Nm.)

If the required torque is unknown, our engineering team can help determine the motor requirements based on your application, load characteristics, duty cycle, and performance targets.

Why Choose an Inrunner PMSM Torque Motor?

Unlike conventional housed motors, a frameless motor consists only of the rotor and stator. The motor is designed to be integrated directly into the machine structure, allowing engineers to optimize performance, packaging, and system design.

Because frameless motors do not include bearings, housing, shaft, feedback devices, or cooling systems, these elements must be incorporated into the final machine design. While this requires additional engineering effort, it provides maximum flexibility and enables highly compact, high-performance direct drive solutions.

Advantages Frameless Inrunner Torque Motor

Compared to conventional geared systems, frameless direct drive motors offer:

  • Higher positioning accuracy
  • No gearbox backlash
  • Lower maintenance requirements
  • Higher efficiency
  • Compact machine integration
  • Improved dynamic response
  • Increased system reliability

These advantages make inrunner PMSM torque motors a preferred solution for robotics, high tech equipment, medical devices, and advanced automation systems.

Need Help Selecting the Right Motor?

Every application is unique. If you are unsure which motor series best fits your requirements, our engineering team can help evaluate torque, speed, thermal performance, installation constraints, and environmental conditions to recommend the most suitable solution.

Available Magnetic Innovations Inrunner PMSM Torque Motor Solutions

The Magnetic Innovations IR-F series covers a wide performance range, from compact precision motion systems to demanding industrial automation applications. Available in three outer diameter and multiple stack heights, the IR-F series enables engineers to optimize torque, speed, thermal performance and installation space for their specific application.

IR-F 52

L'IR-F 52 allie puissance et construction compacte, avec un diamètre extérieur de 52 mm (2,05 pouces). Ils offrent des valeurs de couple maximales allant de 0,49 Nm à 1,44 Nm

IR-F 85

L'équilibre parfait entre puissance et précision, avec un diamètre extérieur de 85 mm (3,35 pouces). Les moteurs de la série IR-F 85 délivrent un couple maximal important de 3,5 Nm à 7,9 Nm.

IR-F 170

La série IR-F 170 est conçue pour les applications industrielles exigeantes, avec un diamètre extérieur de 170 mm (6,69 pouces) et fournit un couple maximal allant de 31 Nm à 70 Nm.

Contacter notre équipe d'assistance

Si vous souhaitez recevoir un devis, si vous avez une question sur nos produits ou si vous voulez savoir ce que nous pouvons faire pour vous en particulier, vous pouvez remplir notre formulaire de contact. Nous vous répondrons dans les 24 heures.