WIND TURBINE, WIND ENERGY TECHNOLOGY, INFORMATION .D.I.Y. ,WIND POWER.
At the heart of almost every successfull small/medium wind turbine is the pmg, Permanent Magnet Generator.The primary difference to this, and the more commonly recognised Auto Type Alternator, is that they don't require an energised field coil to operate, and don't need to be spinning at approx 2300 r.p.m. to reach optimum output.
As soon as a pmg gets to 250-400 revolutions, the pmg coils begin to generate generous power. As long as the wind turbine blades set can maintain a reasonable rpm within the pmg's power production band you can get quite impressive outputs, rising with wind force obviously, green energy has never been so practical.
Just spin the rotor/ blades by hand and they begin to make some power, enough to begin to light a 12v halogen 50 watt bulb.
Due to any wind turbines harsh working enviroment, all pmg's needs to be robust moisture resistant, and obviously capable of withstanding high rpm for sustained periods
BELOW ARE PMG'S FOR WIND TURBINES
A. DISSEMBLED VIEW OF A MODERN PMG
B. 
C. 
pmg 'A ' makes 1300watts at only 500rpm and 2kw-640rpm. 250-450 rpm would be a typical rotation speed with a decent set of blades, higher rpm in a very strong wind. 'B' is a chinese finned alloy 1.2 kwatt pmg design on a turbine i stocked recently.
C. is used on small 300-500watt Chinese turbine. pmg units can get warm when producing good amps from wind energy , so thick alloy or finned alloy casings absorb and help disperse this heat into the air.
As the name suggests all P.M.G.'s initially produce Alternating A.C. electricity this will often require Rectification to D.C., using a Full Wave Rectifier 'D'. Frequently this is now incorporated into a self contained rectifier/charge regulator unit 'C'
Some, intended for larger output wind turbines, even feature l.e.d. output displays, or output meters. Charge controller 'C' internally has 3 rectifiers a dump load voltage sensing & charge control all within this one unit, supplied with Chinese wind turbines who do make more than any other country.
C D 
3 phase (left) & 2 phase bridge rectifiers.
F An Ammeter from turbine output is recommended this was £8.00 off e bay.
multiple Gel or lead acid 12Volt leisure batteries (F) can be used to stockpile power for windless days, this also enables the use of higher current equipment like heaters T.V.'s microwaves without severe voltage drop which would occur with only small capacity batteries, inverters cut off at 10.5v to avoid damaging batteries by seriously discharging them too often.
Pmg's can also produce higher voltages aimed at Grid tie inverters, which avoid needing a set of batteries, but mean you cannot store energy produced for instance at night when consumption would likely be low. Some like these can be directly connected to a 48+ volt wind turbine, like the Windmaster on the left, which ties into your home supply to slow the speed of your meter by contributing to your energy use.
(C) Windmaster for 48v+
(D) Inverter,12Volt to 230 A.C. . Xantrex charge controller.
Many wind turbines for sale don't include any charge regulator/controllers in the price, these Xantrex are about £170+ so bear this in mind if comparing products prices, using a large capacity battery bank largely negates the need for charge control, you can connect an overcharge diverter to 'dump' excess power to a garage/ basement heater which works out cheaper.
Smaller turbine outputs are improving steadily and they install more easilly, those pictured below all produce 200-600 watts max@ 12 volts, but sometimes turbines are put up at at untypical heights to get best test results 50+ feet !.
You can have several running rather than one larger unit, (if you have suitable sitings) if preferred. Pics courtesy of google.
Blades sets can be made of wood fibreglass grp alloy carbon fibre or nylon derived plastics, which are very resilient.
400w 200w (400 claimed) 3-500w 660w-1.400w
Stealthgen Air X Aeolus Futurenergy
Outputs are maximum tested in suppliers graphs at 25-40 mph wind, Some units make higher outputs if using a higher voltage pmg.
Whilst horizontal axis turbines (HAWT) are more common , Vertical Axis wind turbines (VAWT'S) have several advantages, they are usually self regulating, so don't need overspeed protection (often referred to as furl). They need no rudder or similar , as wind approaching from any direction can be utilised, and they are often simpler in design. Most suffer from drag where the forward moving blade slows overall rotation.
The physical shape of the units sometimes can make it awkward to tower mount them, though it has been done. Their theoretical efficiency tends to be lower than a well designed horizontal Turbine at present 15- 20% , though this is likely to improve with several interesting patented advances in the pipeline. Horizontal wind turbine efficiency can approach 50%, better in theory than a petrol engine!, wind energy has never been such a practical proposition.
Large turbines which are set to become an increasingly common sight in high wind energy areas of U.K. especially, they have the blade rotation speed, and pitch carefully regulated for longevity , and as the drive is routed through a robust gearbox , even a Tubine turning at a modest one rev per 5 second in a mild breeze (12 rpm) is making quite a good power output. They feature motorized tracking to follow the Wind , even thermal &vibration sensors on gearbox etc like fitted to helicopters. Some shut down the unit in the event of serious heat or vibration problems.
Many large offshore wind farms are going to be built, some 6-10 miles at sea, which causes less planning objections and higher more productive windspeeds, take a look at the UK WINDSPEED page (at top) on a windy day, often when we have 20-25 mph winds inland, buoys in open sea show up to 50+ mph .
Click on link to see Company Video of V.A.W.T.
http://www.quietrevolution.co.uk/
E MAIL ME aerogen2007@hotmail.com
Now under construction in London Elephant and castle
Proposed efficient 'flexible film' generator