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A common example is "cogging torque" due to slight asymmetries in the magnetic field generated by the motor windings, which causes variations in the reluctance depending on the rotor position. This effect can be reduced by careful selection of the winding layout of the motor, or through the use of realtime controls to the power delivery.
Cogging torque is an undesirable component for the operation of such a motor. It is especially prominent at lower speeds, with the symptom of jerkiness. Cogging torque results in torque as well as speed ripple; however, at high speed the motor moment of inertia filters out the effect of cogging torque.
The torsional deflection of a simple cylinder cannot radiate efficiently acoustic noise, but with particular boundary conditions the stator can radiate acoustic noise under torque ripple excitation. [8] Structure-borne noise can also be generated by torque ripple when rotor shaft line vibrations propagate to the frame [9] and shaft line.
Most motors exhibit positional torque ripple known as cogging torque. In high-speed motors, this effect is usually negligible, as the frequency at which it occurs is too high to significantly affect system performance; direct-drive units will suffer more from this phenomenon unless additional inertia is added (i.e. by a flywheel) or the system ...
When a stator pole is energized, the rotor torque is in the direction that reduces reluctance. Thus, the nearest rotor pole is pulled from the unaligned position into alignment with the stator field (a position of less reluctance). (This is the same effect used by a solenoid, or when picking up ferromagnetic metal with a magnet.) To sustain ...
When = 90° the torque will be maximum. If load is applied further then the motor will lose its synchronism, since motor torque will be less than load torque. [44] [45] The maximum load torque that can be applied to a motor without losing its synchronism is called steady state stability limit of a synchronous motor. [44]
The verdict ordered Ripple Labs to stop selling any assets to professional investors without properly registering them as securities with the SEC, and to pay the court $125 million in civil penalties.
The effect of the inner rotor is to reenforce the field from the stator. [1] Because the stator slips behind the rotating magnetic field inducing a current in the rotor, this type of motor meets the definition of an induction motor.