Okuma has revealed that it is now using its PREX switched reluctance motor to drive the main spindle and optional counter spindle on its LB lathes, instead of the conventional brushless AC motors.
PREX stands for PRimary (coil) EXcited synchronous motor and functions like a traditional reluctance motor. The torque ripple and speed control problems have been overcome using computer-aided design techniques and by embedding controllers that harness algorithms and real-time computing to tailor drive waveforms according to rotor position and current or voltage feedback.
The cost of the drive electronics is offset by the simplicity of motor construction, as it uses no brushes, commutator, rotor windings or permanent magnets. This also makes the motor highly reliable and maintenance free.
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