| Author | Message | ||
     Towjam |
The '07 XBs are equipped with a "494W peak, 38-amp, permanent magnet, 3-phase alternator with solid-state regulator". Yet the '08 models are have a "30-amp max permanent magnet single-phase alternator with solid-state regulator (405 watts@3,000 rpm, 405 watts peak)" Usually new model years bring improvements. But looking at the "charging" specs of the '08 XBs, it looks like we've taken a step back... Am I missing something? (Highly likely - I'm not a wrencher or electrician.) (Message edited by towjam on January 28, 2008) | ||
| Ft_bstrd |
Yeah, the 06 and 07 stators produced too much power causing the stator and voltage regulator to die prematurely. I lost mine at about 15,000 miles. Unless you have everything plus the kitchen sink wired onto it, it will produce more power than is used. This excess power is shorted to ground and is bled off as heat. The new stator will generate less power overall with less power in excess. | ||
| Reepicheep |
Single phase makes the regulator a lot simpler as well. And I bet it gives you the chance to make the stator with one winding with a thicker wire rather then three windings with slightly thinner wires. Its less connections and wiring as well, so fewer things to break there. Should be cheaper to wind as well... and may actually make home enthusiast re-winding closer to possible. The fact that the voltage regulator is now single phase probably lets them make a bigger better stronger one for the same $$ and in the same space limitations as the old one as well. One phase is plenty. Thats a 1000 hz sine wave even at idle. | ||
| Towjam |
Just out of curiosity, what's the difference between "single phase" and "three phase"? | ||
| Reepicheep |
You produce current by moving a coiled piece of conductive wire through a magnetic field. This creates a mechanical drag, and the work done by that mechanical drag is converted to electric current (with some losses). The more circles in your coil, the more electricity is generated, and the more mechanical resistance you have to overcome. Same with the magnetic field, the stronger the field, the more mechanical resistance, and the more current generated. A motor is basically the same device, but you feed electricity into it and it generates mechanical motion. Feed mechanical motion into it, and it produces electricity. Thats why hybrids can use the motor for both accelerating, and for charging the batteries when stopping (regenerative braking). Anyway, if you have one coil, you have one phase. Every time the motor rotates through one resolution, you produce one sine wave. I also just now realized an error in my statement above... 1000 RPM (revolutions per minute) would not generate a 1000 hz (cycles per SECOND) wave, it would be 1/60th of that, or 16hz. Thats still 32 pulses per second though (assuming a full wave rectifier, which ours is). You can put more then one coil in the motor though, under that same magnetic field. So you then get three different sine waves all starting at different times. So when one is going down, another is going up. If you assume the stator has about the same amount of copper and the same size, then you would have 3 coils (each one third the size) of a single phase system. So you would have 3 times the number of peaks, but each peak would represent proportionally less current (as you have fewer windings in each coil). This would give you less "ripple" at low RPM's that you have to smooth out, but not much else. And your battery has no problem smoothing out the 32 hz ripple already. | ||
| Towjam |
Thanks MUCH for the detailed explanation! |
