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My concern I am writing about is with a small generator not producing current or being able to be loaded. First I'll describe the product. I bought a couple mini brushless 3-phase generators (motors). They have a delta wire outlay I assume since they only have 3 wires coming out. They are rated at an Output voltage of : 3V-24V; Output current of : 0.1A-1A; Rated speed of : 300-6000 rev/min; and Rated power : 0.5-12W. The 3 phase motor consists of 9 coils and 12 magnets on the outside. Here is a link to the product.

I wanted DC so I built a 6 diode bridge rectifier to turn the ac into dc, I even bought schottky diodes which supposedly have lower forward voltage. Currently with my drill I can only spin the thing to 900rpm. I know that's on the low end, but out of the diode rectifier I still read 10 volts dc. So I have a working voltage. The problem arrives with the amperage. I could barely get a 5 watt bulb to barely start to turn on to a faint orange glow. Now I have tried generating with a brushed dynamo, if I dont spin it fast enough I don't get the voltage. But! form 0rpms and 0 volts I can feel the load when I try to turn it and it resists.

With this small brushless generators, I was not sure if the load was too small to feel so I over loaded one of them with a 30 watt bulb. I then tried turning the generator with my fingers to see if I could detect a small resistance (given that the generator and rated output is small) but I feel no "load" on the generator, then I proceeded to spin the thing at 900 rpm's with the drill and the voltage with the load connected would not surpass .2 volts and 0.02 amps. I never encountered this type of problem with a small dynamo.

So I can't tell if I don't understand how to work with a 3 phase motor. I know my diode bridge is connected correctly. yet I can't get the little thing to turn on a small 5w bulb, or even to burn the windings by over loading it. not a touch of heat. I know my connections are good because i read the voltage throughout the system. Would anyone have a clue as to why I might not be able to "load" my small generator? I tried 2 of them so its not a faulty singular unit. Any advice would be appreciated, and I apologize for how confusing the whole thing seems, I am trying to make sense of it the best i can myself.

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    \$\begingroup\$ You seemo to have no basic understanding of components, like V/f for motors, or PTC of tungsten is 1:10 to rated temperature \$\endgroup\$ – Sunnyskyguy EE75 Oct 16 '17 at 20:10
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    \$\begingroup\$ It might help if the link you mentioned was actually there. The specifications are not consistent with one another. You should get only 15% of rated voltage at 15% of rated speed (900 RPM). If you are seeing a higher voltage with your meter, you might be reading the peak a a waveform that is not very close to a rectified sine wave. \$\endgroup\$ – Charles Cowie Oct 16 '17 at 20:26
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    \$\begingroup\$ If 6000rpm gives you 24V, 900rpm give you about 3.5V. A 14V car bulb will not light up significantly below 8V. \$\endgroup\$ – Janka Oct 16 '17 at 20:26
  • \$\begingroup\$ that's what has me all confused too with the voltage charles, but I indeed get to 10 Volts. So I was expecting low voltage with high load resistance. for the voltage since its a 3 phase turned into single I read somewhere the 3 voltages sort of overlap and add up to a higher dc. but regardless I just took my drill apart, to be able to spin the thing up closer to 6000 rpm by not going through the transmission of the drill. so I will see what happens there. I definetly know the voltage will go up, but we'll see if it can deliver the 1 amp it promises. \$\endgroup\$ – Robert Dold Oct 16 '17 at 20:35
  • \$\begingroup\$ For all we know, the 24-volt, 1 amp (24 watt) rating may be the DC input to the controller that is recommended for use with the brushless DC motor. The 12 watt rating may be the mechanical output power of the motor. \$\endgroup\$ – Charles Cowie Oct 16 '17 at 20:55

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