Questions about rotor inside common genset like in Indonesian video

Body

Hi all

In attachments are two photos of the insides of one of those 750W usually gas-engine powered gensets just like the guy from Indonesia has on the right side of his motor generator.

I see the slip rings, I see the 2-pole rotor (so this will take 3600rpm to make 60hz) and inside the plastic housing on one end of the rotor is a diode (actually there are two) and these connect to the ins and outs of the coils somehow....I would think these diodes are sort of "blocking" (big zener?)diodes so that the generator will not produce power until it gets to speed of 3600rpm and makes the 120VAC  or the 220VAC and only then will it let power pass through, so this is a feature to make sure the generator only produces 120VAC and nothing less, especially during start up or warm up and a load is attached to the generator....


Is this correct about those diodes??? Or are they something else?


The other question is about that little ceramic magnet imbedded into the rotor you can see in the photo in attachments....so what exactly is this for??

To help magnetize the core a little bit and give it some polarity perhaps?

Why is there only one?

Is there a hall effect somewhere on stator or small coil that this reacts too and serves as some sort of over-speed governor? (guessing)


Maybe it helps smooth out the sinewave somehow? (but why only one?)


Anyways this is exactly what is inside the Indonesian genset seen in video to the right of the looping motor generator....


perhaps he put in his own rotor of permanent magnets and that is part of it all???

If anyone can answer my questions it would be appreciated...I hope you can all see the photo attachments...

ciaoKone