Induction in this context refers to the act of creating EMF by moving a magnetic field across a conductor, either by physically moving it or by expanding and collapsing the magnetic field with alternating current. The rotational force in these motors is created by magnetic repulsion.
An industrial AC motor is correctly termed an induction-repulsion motor; as they operate by using a high-voltage AC current in the stator to induce a very high current to flow through the aluminum substrate of the laminated motor core. This high current then responds with a high-magnetic flux repulsive force, which causes motion. The nature of the way the poles are wound on the stator defines the rpm this motor will operate at with any given frequency of AC voltage applied.
The only induction with a PM BL motor is the BEMF used for timing, so strictly speaking, I think these would be a 3-phase AC repulsion motor.
Yes, you're right I was probably oversimplifying induction as the use of the charged coil at all, not just the induced voltage flow. As you say the BEMF reading still uses induction, but it's limited to sensing only, not drive.
"The only induction with a PM BL motor is the BEMF used for timing, so strictly speaking, I think these would be a 3-phase AC repulsion motor."
Besides timing, the BEMF is also used for braking and or regeneration. Strictly speaking, all (practical) electric motors use magnetic repulsion, these motors are called DC brushless motors. Obviously, no field coil is needed due to Perm Magnets.
Paul Krajewski:
Sep 28, 2017 at 09:39 AM
Induction in this context refers to the act of creating EMF by moving a magnetic field across a conductor, either by physically moving it or by expanding and collapsing the magnetic field with alternating current. The rotational force in these motors is created by magnetic repulsion.
An industrial AC motor is correctly termed an induction-repulsion motor; as they operate by using a high-voltage AC current in the stator to induce a very high current to flow through the aluminum substrate of the laminated motor core. This high current then responds with a high-magnetic flux repulsive force, which causes motion. The nature of the way the poles are wound on the stator defines the rpm this motor will operate at with any given frequency of AC voltage applied.
The only induction with a PM BL motor is the BEMF used for timing, so strictly speaking, I think these would be a 3-phase AC repulsion motor.
Cheers,
mnem
*Slightly repulsive*
quadmcfly:
Oct 30, 2017 at 09:45 AM
Yes, you're right I was probably oversimplifying induction as the use of the charged coil at all, not just the induced voltage flow. As you say the BEMF reading still uses induction, but it's limited to sensing only, not drive.
Chris Barth:
Nov 15, 2017 at 11:49 PM
"The only induction with a PM BL motor is the BEMF used for timing, so strictly speaking, I think these would be a 3-phase AC repulsion motor."
Besides timing, the BEMF is also used for braking and or regeneration. Strictly speaking, all (practical) electric motors use magnetic repulsion, these motors are called DC brushless motors. Obviously, no field coil is needed due to Perm Magnets.