Alternator Designs (powerpoint)

[@HurricaneWindPowercom]

Hi Hugh ....a couple questions if you don't mind. Toward the end of the video speaking on corrosion of the Neo magnet have you found the black in appearance epoxy coated magnets from the factory to have the same problems over time? Secondly are you indicating that the lack of efficiency in the ferrite design allows the turbine to turn while still under a load due to the lack of generator efficiency i.e. continuous power production versus an instantaneous power spike with the generator load killing the momentum.... If this is the case would you agree that the going up to magnets up to N 52 while increasing the efficiency or strength of the generator kill the performance of the turbine due the to heavier load from the generator on the blades.thus overkill in the magnet...Not sure if I am saying this well hope you get the point

[@scoraigwind]

hi tony yes the corrosion still happens even with various coatings on the magnets. Just like chrome plated cars still corrode. It's mainly a problem in maritime locations. Can be very rapid in tropical locations. Can be dealt with using oil but still a disappointing result. Highly efficient alternators will run at constant speed (rpm) over various loadings. In high winds you want the blades to speed up or they will stall. Having some loss of voltage in the circuit (whether in the coils or a series heater in the circuit) allows a change of speed. Weaker magnets need more turns of thinner wire hence more internal resistance in the coils which allows higher speed. Your vehicle alternators also speed up due to internal impedance of the reactive kind but this tends to limit maximum output and the shape of the power/speed curve is hooked downward rather than being hooked upward as we would wish. The machine overspeeds rather than stalling which if anything is a worse outcome. cheers Hugh

[@HurricaneWindPowercom]

Hugh Piggott I watched your 20 minute power point because I have experienced some of the pains you have with radial designs. I have reached some of the same type dead ends .We build axials as well and want to use mppt technology to build something we can get a real 2 kw rated wind turbine. I know Chris Olsen did something similar and read debate on the bearings and differences in opinion on the designs. We had the Air Boss design that was pretty much built on the 1.4 and 2.8 designs but as always we want more power and I don't want to stack stators to make the power which leaves me with increasing the diameter and surface area of coil and magnet presumably . The reason for my question is that from what I deduct from the comment simply adding stronger magnets i.e. N 42 to N 52 is a recipe to stall the turbine and secondarily increase blade strain and end up with turbine with snapped off fiber glass as in the photos in your power point? I see a lot of people using n 52 in this design and thing that it would be undesirable due to the increase tolerance to heat for that stronger magnet as well. People change and evolve Hugh and I think you will forever in your mind have me as a delco guy which is fine. I am a cost effective guy with an open mind. Actually Hugh we build axials as well and really only still build the other delco pma because people still want them typically to replace my competitors alternator which will not so much as charge a battery. We advertise them at what I observe on a wattsview which is about 150-400 watts depending on the voltage environment. I am frustrated that people kill the small wind market with delco wind turbines with 28 inch blades that output 100 watts advertised at 1600. Hugh my questions are about axials not a small alternator referendum from the past. I have moved on from that and am looking at making as much power possible in the most cost effective manner possible.

[@scoraigwind]

Hurricane Wind Power yes if you want more power you need larger diameter magnet disks. Stacking is not cost-effective use of materials. But higher power at high rpm will ideally require MPPT I'd say. I tend to prefer going for larger blade-rotor diameter, so you can get a narrower range of rpm for the same high power, but in lower winds. That way stalling is not such as issue. But if you want high power with small blade-rotor diameter (in high winds) you will need to go for a high cut in speed (and poor low wind performance) or an MPPT controller so as not to stall in stronger wind. Or heaters in series as I do on my big machine here at home.

[@HurricaneWindPowercom]

Hugh Piggott Hugh we would always prefer low wind speed production with larger blades or even a 5 blade design which we have had some good results on our smaller turbines. I am looking for the higher voltage that we can regulate with our midnight down to 12,24, or possibly even 48 volt with one winding. In doing so I have concerns that the required thin ga windings for the higher voltage will not last due to heating concerns. Presumably the larger disk will not shed heat as well. Do you have a design that you might recommend to this end?

[@Ed.R]

Hugh, Thanks for sharing these videos. I've been interested in what you do since I became interested in wind power whilst living on the Isle of Tiree as a child. I learned just how badly neodymium magnets corrode when I helped Lews Castle Collage Stornoway fix one of their wind turbines as a project. I was wondering what you thought of increasing the magnet rotor thickness to counteract the reduced flux of ferrite magnets. The optimum shape of a magnet for flux strength is when the length equals the diameter. Would it therefore make sense to substitute for example 40 x 25 x 10mm neodymium for 40 x 25 x 30mm ferrite probably 3 magnets stacked. They still wouldn't be as strong as neodymium but perhaps the area could also be increased slightly if necessary. I wonder if an optimum can be achieved if the thickness of the rotor is maximised first then the area of magnet poles is increased to gain the required flux strength. My concern is that the increased weight of the magnet rotors will reduce the turbines responsiveness to gusty wind conditions.

[@JamesBiggar]

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[@scoraigwind]

Golly I wonder what brought all that on.

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