Yes, I had not heard of it before this thread, but that's what 57Chevy described and that appears to be the design of the BorgWarner unit as shown in the YouTube video attached to their product web page. The magnetic coupling between the fixed winding and the rotor surrounding it is radially through the cylindrical area at the open end of the cup-shaped rotor, and axially through the other end. That's a magnetic flux path, with as low reluctance (the magnetic equivalence to resistance) as they could manage.
BMW magnetless motors
Interesting idea, do away with rare earth magnets so vehicle price isn't tied to the commodities price and then instead of an old induction motor like Tesla, power the rotor via brushes and achieve a motor with adjustable BEMF. The extra thermal load from the rotor electromagnet is well made up by being able to turn down the magnet at light loads and at high speeds. Quite clever really. Can't wait till people start crashing these
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This is kind of interesting...I wonder if there is a weight savings? I'd assume the armature windings are wound onto laminates. I'm betting this motor has multiple internal windings so it can essentially make several magnet poles with them. They probably rotate with the actual armature.Yes, I had not heard of it before this thread, but that's what 57Chevy described and that appears to be the design of the BorgWarner unit as shown in the YouTube video attached to their product web page. The magnetic coupling between the fixed winding and the rotor surrounding it is radially through the cylindrical area at the open end of the cup-shaped rotor, and axially through the other end. That's a magnetic flux path, with as low reluctance (the magnetic equivalence to resistance) as they could manage.
Due to the extra rotor mass needed to provide sufficient magnetic coupling between the rotor and the excitation winding, I assume that this is heavier than a typical brush-and-slip ring design.This is kind of interesting...I wonder if there is a weight savings? I'd assume the armature windings are wound onto laminates. I'm betting this motor has multiple internal windings so it can essentially make several magnet poles with them. They probably rotate with the actual armature.
It appears to have a simple single rotor excitation winding. It's an automotive alternator, so excitation current is controlled to determine alternator output voltage, while the stator phases would feed a simple diode rectifier.
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