The basic principle
Every electric motor turns electrical energy into rotation by using magnetic fields that push and pull on one another. In a PM motor, the rotating part (the rotor) carries permanent magnets, and the stationary part (the stator) carries windings that the drive energises to create a rotating magnetic field.
The rotor's magnets lock onto that rotating stator field and follow it. Because the rotor turns in step with the electrically created field, PM machines of this type are called synchronous motors.
Main components
The stator is the outer, stationary assembly of steel laminations and copper windings; energising the windings in sequence produces the rotating field. The rotor is the inner rotating assembly that holds the permanent magnets. The shaft transmits torque to the load, bearings support rotation with minimal friction, and the housing provides structure and helps dissipate heat.
A variable-frequency drive (VFD) or inverter almost always accompanies a PM motor, supplying the correctly timed currents that keep the rotor synchronised across the speed range.
Why PM motors are efficient
In an induction motor, current must be induced in the rotor to create its magnetic field, and that induced current produces resistive (I²R) heating — a permanent loss. A PM motor's rotor field comes from the magnets themselves, so there is little or no rotor current and that loss category largely disappears.
Removing rotor losses is the single biggest reason PM motors reach the higher IE efficiency classes more readily than induction machines, especially at partial load.
Magnet material choices
PM motors can use rare-earth magnets (such as neodymium) or non-rare-earth magnets (such as ferrite). Rare-earth magnets are stronger per unit volume; ferrite is weaker but far cheaper and free of supply-chain restrictions.
A ferrite-based PM design compensates for lower magnet strength through careful electromagnetic design so that motor-level efficiency remains high. The ferrite motor and ferrite-vs-neodymium pages explore this trade-off further.
Where PM motors are used
PM motors are found wherever high efficiency and good part-load performance matter: pumps, fans and compressors, conveyors, traction, marine propulsion and HVAC systems. Their efficiency advantage is largest in continuous-duty applications with long running hours.
To discuss a specific application, get in touch with the EKMO team.
EKMO Motor Licensing
IE6 ferrite motors. Production-ready. Available for licensing now.
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