What’s the difference between cogging torque and torque ripple?
‍

Featuring Nicolas Giraudo, Chief Commercial Officer at Alva Industries

They’re closely related concepts in motor design, especially for permanent magnet motors, but they aren’t the same.

In this episode of Tech Torqs, we explain how cogging torque is a positional effect caused by the interaction between rotor magnets and stator slots. It’s present even when the motor isn’t energized and becomes most noticeable at low speeds.

Torque ripple, on the other hand, is a dynamic effect that only appears during rotation. It’s caused not only by cogging torque but also by control challenges, winding harmonics, and magnetic saturation.

To summarize:

• Cogging torque = static, position-based, caused by rotor-stator geometry
• Torque ripple = dynamic, speed-dependent, influenced by control and design factors

Understanding the difference is essential for minimizing unwanted vibrations and achieving smooth motion—especially in high-precision applications.

If you have a question about motors or motion systems, share it in the comments on our LinkedIn post or send it to us directly - we might feature it in the next Tech Torqs episode.