Environment

# Torque vectoring gears for smaller, more efficient wind turbines

Torque vectoring gears for smaller, more efficient wind turbines
Wind farm near Wadena, Indiana (Image: John Schanlaub via Flickr)
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Wind farm near Wadena, Indiana (Image: John Schanlaub via Flickr)

Torque vectoring is a relatively new technology that has been employed in automobile differentials, most commonly all-wheel-drive vehicles, that allows the amount of power sent to each wheel to be varied. Scientists at the Technische Universitaet Muenchen (TUM) have now adapted this technology to wind turbines, to eliminate the need for converting the alternating current produced by the turbines into direct current and back again before it is fed into the grid.

As the rotational speed of the wind turbine, and thus the generator that is connected to the rotor via a gearbox, changes depending on the force of the wind, the alternating current it produces must first be rectified so that it can be fed into the grid with the correct frequency – usually 50 or 60 hertz. To accomplish this, the alternating current from the wind turbine's generators is transformed into direct current using giant rectifiers before being transformed back into alternating current of the right frequency. This twofold conversion process results in a loss of close to five percent.

To attain the desired grid frequency of 50 hertz, a generator with the usual two poles pairs must operate at a synchronous speed of exactly 1500 revolutions per minute. The scientists at TUM developed an active torque-vectoring gear similar to a controlled differential in a motor vehicle, that could operate at this speed in spite of the variable input rotational speed of the rotor.

In the TUM system, as in conventional designs, planetary gears generate most of the transmission required, but these are supplemented by a torque-vectoring gear with a supplemental electric motor that can be used as both a drive and a generator. This motor allows the power from the rotor to be either boosted or diverted to ensure a constant rotational speed for the generator. The researchers say that an electric motor of about 80 kW is sufficient for a 1.5 MW wind turbine.

By doing away with the need for giant rectifiers, the TUM system results in a lighter power train that doesn't require as large a wind turbine nacelle. Also, the researchers say that because a robust, low maintenance synchronous generator can be used, there's no need for powered electronics for frequency adjustment, which results in a boost to the overall efficiency of the wind farm.

Todd Dunning
Nuclear power is just for people who just want to have reliable, cheap, clean electricity - basically, they\'re just not hip. Wind doesn\'t generate a minute fraction of the power, but it does look a lot cooler. You can get chicks if you say you\'re for alternative energy.

OK, wind costs over 60 times more per kilowatt to install and maintain. But do we really need all that electricity after all? The message of consumerism it sends out is so... greedy. We should just use less electricity instead, because we\'re bad if we use more. I don\'t know why... we\'re just bad.

And though you need over 1,000 acres of windmills to produce the power of one 3-acre nuke plant, it\'s still futuristic and green. Besides, that nuclear stuff is scary. Don\'t they make bombs out of that?

The nuclear waste from one reactor type is actually the fuel for others, like the way the sun works. But again, that physics stuff is confusing, and anyway I heard the sun is responsible for global warming. So speak truth to power.
B Alingh
You make many valid points Todd, but who are you ranting to? It is not citizens that are blocking nuclear plants, it is politicians. With so much bureaucratic red tape, high capital costs and a fearful(albeit misguided) view by America, nuclear power is not a viable option to power America right now(unfortunately). Nuclear may be cheaper per kilowatt, but the overall project cost for a nuclear plant is very high. With the current financial situation, bodies have chosen to go with the \'chip away\' approach to the problem and build wind farms. Though they do not put as much energy into the grid as nuclear, they show citizens what can be done and inspire citizens to think outside the box, and provide energy and jobs.
Wind turbines do not produce much energy now, but the industry is very young. We see many articles on sites like gizmag with the headline \'major breakthrough in wind/solar efficiency\' without seeing any chances in reality, but real changes are in the pipeline. The standard turbine installed over the past decade has been of 1.5MW size, on the near horizon we have many manufacturers releasing models of 5 and even up to 10MW onshore turbines. The current investment is necessary to drive future technology and create a robust industry. Though I agree that we need to end this boycott of nuclear plant construction in the USA, your rant may have been better suited against something like coal or oil, but wind? Do not let the perfect be the enemy of the good.
Timothy Loose
If the 1.5 MW wind turbine requires an 80 KW motor to power the torque vectoring scheme, isn\'t that also a 5% loss of energy, just like the process of converting AC to DC and back to AC?
Todd Dunning
\"Though they do not put as much energy into the grid as nuclear, they show citizens what can be done and inspire citizens to think outside the box, and provide energy and jobs.\"

Casualfan, your statement perfectly validates what I am saying. Alternative energy is about coolness, not the task of generating electricity. That\'s fine, just don\'t continue to harm our energy production - and your wallet - by burning taxpayer money nonproductively to \"inspire citizens to think outside the box\".

If nuclear/wind was 80/20 productivity, or even 90/10, then wind would be worth persuing. But a dollar spent on wind produces a fraction of one percent of the electricity produced by nuclear. That\'s worth a \'rant\'.
Eric MacAfee
hey Todd, you took casualfan\'s words out of context. and made no defense to his real points against your financial argument.
-capital costs of nuclear energy are high, wind farms are being built because of lower initial costs, while providing ongoing work in bad economic times -putting money into the industry now leads to improved technology, and lower production costs over time.
(though i am paraphrasing, and may have misinterpreted)
The suggestion that alternative energy is about \"coolness\" is absurd. It\'s about getting electricity from renewable resources instead of finite ones. Resigning to nuclear forever and not pursueing alternatives seems unwise. Uranium is a finite resource, nuclear waste is a real problem. both of which worsen over time, as opposed to renewable energy becoming more affordable.
Also, land use is not really an issue with wind farms when the land also doubles for food production. or alternatively, they aren\'t on land at all.
I am not a nuclear physicist and do not know about how\"The nuclear waste from one reactor type is actually the fuel for others, like the way the sun works.\" but i would be interested to learn. though i suspect, that despite your sarcasm, nuclear waste is still eventually produced, and that it is still hazardous.
that said, i am certainly not anti-nuclear. I just can\'t see a future where renewable energy does not play a vital role.
Greg Zeng
@Eric MacAfee: \"Uranium is a finite resource, nuclear waste is a real problem\"

How many millenia are you think for? Australia & other nations has too much atomic fuel. Waste is not a problem Visit inland Australia. As already stated: the politicians are too heavily lobbied by the traditional industries (organic fuels) and scientific idiots (\"greenies\").

I\'m against wind power. Look at the emerging economies that USA is so much in \$\$ debt towards: Japan, Taiwan, China.

Retired (medical) IT Consultant, Australian Capital Territory
Eric MacAfee
@greg zeng \"Waste is not a problem\"
Thanks for the correction on uranium availabity. but i don\'t know how you can say waste is a not a problem. The problem is it\'s a health hazard, and it remains hazardous for a long time. Unless this is an issue has been solved already. i won\'t pretend i am any kind of expert. And would be relieved to be corrected.
I do not understand why anyone would be opposed to wind power. It does not sound like a logical position. The financial argument has already been given and responded to. It\'s an investment for the future, we know it\'s a field that is still becoming more efficient because we are commenting on an article about improved wind turbines. in summary, i would be interested to hear from anyone : what\'s the permanent solution for nuclear waste? and why is wind power not worth pursuing?
christopher
Yeah - spent nuke is yucky - but it\'s such a *small amount* of stuff, it\'s really not hard to responsibly look after it - we\'re only talking about a ute-load of stuff per year y\'know.

Wind turbines are cool - but they wear out real fast, look massivly ugly, make tons of unpleasant noise, cost insane amounts of money to buy, then more insane amounts to maintain, are dangerous to sport-aviation and wildlife, and ruin the ability for people to enjoy the environment nearbye.