Alternative Energy Solutions

Building an effecient Generator?

Hey guys keen on building a generator that will be used on a wind turbine to produce around 250 watts can anyone recomend a diameter for the wheel on which the coils and the magnets are placed on

All of these factors are dependent on each other. There is no right answer.

EMF results from the rate of change of linked magnetic flux; in other words, how rapidly the coils cut across magnetic lines of force. Let’s see how this plays a part in each of your questions. I’m also assuming your magnets are on the wheel and the coils are outside (an inrunner configuration).

Wheel diameter: The greater the wheel diameter, the greater linear velocity the magnets will have, so the more EMF will result. Greater diameter will also increase the torque the coils exert on the drive shaft.

Magnet size: bigger magnets will generate more total flux, but of course over a larger area. Rare earth magnets have a fairly uniform flux density so making them bigger won’t get you much of a gain; the magnets of course need to be close to the size of the coils or you will have periods of constant flux, which generate no power. Heavier magnets will give your wheel greater inertia too.

Turns: linked flux is multiplied by the number of turns. If you add more turns, you will make more power and more torque, but at some point your coils will become so large that not all of your windings will be close to the magnet. The more turns, the higher resistance as well, so you will lose more power with more windings.

Wire gauge: you should choose a wire gauge that suits the amount of power you want to generate. If you use too narrow a wire it will heat up and fail under heavy current output.

Shape: this will be dictated by the manufacturer, most likely. Square coils are very common. I suggest you narrow this down by shopping for magnets first.

Dimensions: the wheel diameter, number of poles, windings, gauge, and flux density will determine how many magnets you can fit. Don’t leave empty spaces between them if you can help it.

Mounting material: if you wind your coils around magnetic cores, like laminate or ferrite, you will get more flux through the windings. Otherwise, stick to non-ferromagnetic materials. Further, many people overlook the fact that magnets experience a force when they move near a conductor. If you make the whole assembly out of aluminum you will waste a large amount of energy in eddy current loss. You should choose your materials based on the type of weather you expect at your site.

Hope this gets you well on your way.

HOW TO BUILD A WIND TURBINE GENERATOR TOWER, DIY ,FREE ENERGY

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