You asked and I shall give the answer. Tesla.
https://teslauniverse.com/nikola-tesla/patents/us-patent-390721-dynamo-electric-machine Instead of giving the source it's proper due they tried to subvert the origin of this. Tesla was the inspiration and it was high jacked by profit takers instead of shared in the open and for free. Now they are trying to latch onto this technology and claim it as their own. I have been trying to get this out there for over 10 years now. Then the final stroke came and they latched onto the zero force motor which is a half baked implementation of the two phase induction motor generator Tesla devised.
If you want to know more about this device then research this patent heavily. The problem is a lot of external apparatuses were left out of this design due to the patent process but all you have to do is look into other patents by Tesla that fill the voids in this patent.
The premise behind this device is that it maintains the 90 degree difference between the two fields (E and M). The M is locked into a conversion loop between the rotor and field coils. The Magnetic field is converted into electric between the rotor core and field core. When this is done the magnetic field is formed and it cuts the field coils on it's way to the field coil which generates a high voltage in the field coils which radiates into the rotor coil transforming the E field to a heavy magnetic field which loops back to the field core generating more E field and so on. The magneto is used to generate high voltage that will feed a cap dump circuit which feeds the field coils to start the process.
The rotor coil can be tapped to a certain depletion level and still maintain the magnetic loop between the rotor core and field core. So this system will have to be designed with a max load in mind. Scale being the only limit to the max load.
I'm glad you started looking into Mr. Lewin. He was my first online teacher of physics. Look for the water drop experiment and you should start to see the loops that can be created and harvested for energy channeling.
By the way, if you get rid of the rotor magnets and use heavy coils self terminated and open and close the coils at the proper time you can convert that to an AC sign wave that can be used however you want through an additional transformer.
Tesla called this device a rotating transformer, And one with a feedback loop designed in the electric to magnetic conversion process. It is also self aligning so you don't have to make a perfect machine to get this feedback effect. I would also suggest that this might just be a steady state motor that if you take anything out of the system it compensates. Retarding the rotor from the synchronous position generates more current in the rotor. Speeding up the rotor also would generate additional energy. Kinda cool right?
I also think that the rotor should have a virtual ground connected to it to dissipate the static electric field that would form inside of the generator section. This would allow for a flow to happen in the device which should increase the output as well.
It is this system that he had Westinghouse build for his Roadster experiment with the addition of the Bessemer steel that Tesla found to be more efficient working with the magnetic cores. Now ask yourself, Why would they get rid of the cheapest way to make a soft steel that has better performance then most core material? Tesla gave Westinghouse the idea to use it in their transformers that he had made for him by them. Now not many businesses use Bessemer Steel except for wire brushes. I tried to source it but no one seems to know about it but yet this was the first cheapest way that they made all steel products like railroad tracks and steel for buildings. Yet for some odd reason it was intentionally forgotten. Ask yourself how they could build steel structure buildings way back and they would last a very long time. Now ask yourself why they got rid of this material? Another question is this: Did Westinghouse make superior transformers after being told about this by Tesla? The answer is yes they did.