Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Motion control and drives

Synchronous motor

Also known as: AC synchronous motor

German: Synchronmotor

In electric drives, a synchronous motor is an AC motor whose rotor turns at exactly the speed of the rotating stator field, because the rotor field is produced by permanent magnets, DC excitation or magnetic reluctance.

  • Motion control

In one sentence

A synchronous motor is an AC motor whose rotor turns exactly with the stator's rotating field, without slip.

Example

Large compressors in a refinery use DC-excited synchronous motors, while the plant's servo axes use permanent-magnet synchronous motors.

How it applies

  • Engineering: Synchronous motors offer high efficiency and exact speed. Most are operated with a frequency inverter or servo drive; line-start variants exist for some applications.
  • Commissioning: The drive needs rotor position or a suitable sensorless method; motor data identification is important.
  • Operation: If the load exceeds the pull-out torque, the motor falls out of step; drives detect and trip on this.
  • Documentation: Specify the motor type in drawings and parameter lists precisely (PMSM, reluctance, DC-excited), because drive settings and hazards differ, for example voltage generated at the terminals when a PM rotor is turned.

Synchronous vs. induction motor

The synchronous motor has no slip and runs at field speed. The Induction motor needs slip to induce rotor currents and runs slightly slower than the field.

By knowledge.aitechdoc.world · Published September 26, 2026 · Last reviewed

Source: IEC 60034-1, Rotating electrical machines — Part 1: Rating and performance

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Knowledge and are not part of any standard.

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