- #1
carmatic
- 92
- 1
consider first , an induction motor... a rotating magnetic field is applied to an electrically conductive rotor, and the eddy currents induced will oppose the change in magnetic field experienced by the rotor, hence the rotor gets torque
in an induction motor the rotating magnetic field is caused by coils of wire having electricity passed through them in sequence...
but what if the rotating magnetic field is provided by actual permanent magnets placed on a rotating disc? this will be useful in applications where the controlled transfer of torque is more important than having the output RPM be equal to the input RPM ... the latter can never happen because induction depends on slipping between the input and output, so it is something like a wet clutch which is supposed to always slip(see the powertrain to the front wheels of the Ferrari FF)
if you vary the distance between the magnets and the rotor, you can control how much torque will pass to the output shaft
furthermore, if the magnets and rotor are arranged as concentric cylinders and torque control is achieved by moving the smaller cylinder into larger cylinder, and if the rotor is a squirrel cage design with a slight twist to it so that there is a nett attraction/repulsion differential along the axis of the cylinder (like a screw under torque) which would push the smaller cylinder out of the larger cylinder, it could behave similar to a traditional slipper i.e. the harder you press on it, the more torque goes through... the difference being that it is literally like a screw, the amount of pressure you need to provide will depend on the amount of torque going through, so where input torque and RPM varies this could be a complicating factor
in an induction motor the rotating magnetic field is caused by coils of wire having electricity passed through them in sequence...
but what if the rotating magnetic field is provided by actual permanent magnets placed on a rotating disc? this will be useful in applications where the controlled transfer of torque is more important than having the output RPM be equal to the input RPM ... the latter can never happen because induction depends on slipping between the input and output, so it is something like a wet clutch which is supposed to always slip(see the powertrain to the front wheels of the Ferrari FF)
if you vary the distance between the magnets and the rotor, you can control how much torque will pass to the output shaft
furthermore, if the magnets and rotor are arranged as concentric cylinders and torque control is achieved by moving the smaller cylinder into larger cylinder, and if the rotor is a squirrel cage design with a slight twist to it so that there is a nett attraction/repulsion differential along the axis of the cylinder (like a screw under torque) which would push the smaller cylinder out of the larger cylinder, it could behave similar to a traditional slipper i.e. the harder you press on it, the more torque goes through... the difference being that it is literally like a screw, the amount of pressure you need to provide will depend on the amount of torque going through, so where input torque and RPM varies this could be a complicating factor
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