Going into the tech a bit deeper, one of the main problems of a perm mag generator, shared by for example by motorcycles,is that whenever the input shaft is spinning fast enough it will make lots of power. If you remove the load the voltage will shoot up to trueley awesome levels, 100V and above, and may destroy the rectifier diodes or even get high enough to 'punch through' the insulation on the generator windings.
Most motorcycles just dump all the power into a load, either charging the battery or shorting it to ground (the regulators are all big finned heat sinks!). They use a pulsed duty cycle in the regulator that delivers more or less power into the battery as sensed and needed, the rest goes to ground. Primitive, wasteful, and hot running, but compact, cheap and reliable if engineered correctly. Some wind generators that use PMs also use a similar approach as you noted, dumping excess generated power into a dump load. But the problem with this in a wind genny is that the load can change its resistance as it heats up and so be less able to absorb the power, and the magnets can get hot as the wind genny is running at such a continuous very high power output condition, so loosing strength and allowing run-away to occur. A better design uses a switch mode regulator that senses the output voltage and then controls the switch mode regulator. A switch mode device takes the input power, chops it up in tiny slices, converts the voltage to current or VS VS by changing it into magnetic fields in an inductor and electric fields in a capacitor as required by the feedback circuit monitoring the output voltage, and then splicing all the 'converted' pieces back together to form the 'set for' output voltage and rated/demanded current. The advantage of this design is that it doesn't waste power as only as much as is needed is created, and so it makes much less heat and can be much more compact, and the output voltage doesn't change much if at all when the load is removed or changed. But, if this approach is used alone, it cannot prevent run-away. You still need a blade furling or braking scheme. Air Marine uses both in that they use some of the power the genny makes in high winds to slow the blades, by feeding it back into the windings so that they act as a constant power motor and brake in the opposite direction that the wind is trying to turn them. Also, the blades twist and this makes them less efficient and slows them down. This makes the unit totally self tending regardless of wind speed. As far as I know, Air Marine is alone in offering all these features in such a small compact model. -Ken _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
