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Build a 5m rotor diameter

Posted: Jun 09 2019 6:25am
by jlcortex
I'm thinking of starting a serious project
In my opinion if you build a wind turbine you have to make it big, What do you think?

Rotor diameter = 5m
A 5m rotor can get more than 5000W but I would like to optimize for slow wind, about 6m/s, I am calculating 2500W or so.
I am thinking to build blades in wood and use a multiplied hub motor as generator.

It has sense?

Re: Build a 5m rotor diameter

Posted: Jun 09 2019 10:59am
by Lebowski
I would go vertical, somehow seems easier for diy...

https://en.m.wikipedia.org/wiki/Vertica ... nd_turbine

Re: Build a 5m rotor diameter

Posted: Jun 10 2019 2:00am
by jonescg
A hub motor would probably be a good match considering the low speeds. Hope to see this progress :)

Re: Build a 5m rotor diameter

Posted: Jun 10 2019 3:53pm
by jlcortex
Captura2.PNG
Captura2.PNG (342.82 KiB) Viewed 745 times
I like horizontal wind turbines. About hub motor, I see hub motors very simple, reliable and cheap. I am thinking about use a 500W 12V hub motor at 5X the nominal speed to get 2500W, it is very big motor, i think 2500W is not problem if it spin 5 times faster.

Re: Build a 5m rotor diameter

Posted: Jun 10 2019 4:18pm
by billvon
jlcortex wrote:
Jun 09 2019 6:25am
A 5m rotor can get more than 5000W but I would like to optimize for slow wind, about 6m/s, I am calculating 2500W or so.
I am thinking to build blades in wood and use a multiplied hub motor as generator.
A 5m diameter rotor, in 6m/s wind, is going to get 2500 watts at 100% efficiency. At more reasonable efficiencies expect 1000 watts or so. Also 6m/s is about 14mph which is a pretty strong wind. We rarely see winds above 12mph down here.

Re: Build a 5m rotor diameter

Posted: Jun 10 2019 11:16pm
by Hillhater
jlcortex wrote:
Jun 10 2019 3:53pm
..... I am thinking about use a 500W 12V hub motor at 5X the nominal speed to get 2500W, it is very big motor, i think 2500W is not problem if it spin 5 times faster.
Why 12 volts ? ....you will be dealing with high amperage .
48 -60 v would be more practical.
Also check the efficiency of the motor at 5X normal operating speeds.
A 3kW hub at normal design speeds would seem to be more realistic and still cheap.?

Re: Build a 5m rotor diameter

Posted: Jun 11 2019 4:16pm
by jlcortex
Hillhater, I am meaning 12V hubmotor spinning at 5X the nominal speed so it will be 60V, rated current will be about 42A.
The hub motor is a huge electric motor, the power is low because the RPM is very low, but I think nothing prevents the engine from spinning much faster than it does on a bike.

this is my wind:
weatherspark.PNG
weatherspark.PNG (39.29 KiB) Viewed 694 times
https://weatherspark.com/y/42614/Averag ... Year-Round

this other site is a map with wind power density
https://globalwindatlas.info/

136W/m2 in my area at 50m. I am not an expert but I think the calculation should be something like that:
Average Power = Wind power density * Area * turbine efficiency * generator efficiency = 136*19,64*0,4*0,86 = 918W
My tower will not 50m so I estimate near 700w average, about 6MWh/year

Re: Build a 5m rotor diameter

Posted: Jun 11 2019 5:00pm
by jlcortex
I just realized that the 12V hub motors are not very popular, but some items can be found:
https://www.alibaba.com/product-detail/ ... 78a5MKzt68

Re: Build a 5m rotor diameter

Posted: Jun 11 2019 5:38pm
by billvon
jlcortex wrote:
Jun 11 2019 4:16pm
My tower will not 50m so I estimate near 700w average, about 6MWh/year
I get 200w average, assuming 8mph wind average.

Tower minimum height is going to be 12.5 meters plus the height of the tallest object within 200 meters of the turbine.

Re: Build a 5m rotor diameter

Posted: Jun 11 2019 6:19pm
by Hillhater
jlcortex wrote:
Jun 11 2019 5:00pm
I just realized that the 12V hub motors are not very popular, ....
That was one reason i suggested using a higher power/voltage rated motor ...
Another being the efficiency/heat build up if you use a 500W motor to regen at 5x its rating

Re: Build a 5m rotor diameter

Posted: Jun 12 2019 3:19am
by Punx0r
jlcortex wrote:
Jun 11 2019 4:16pm
The hub motor is a huge electric motor, the power is low because the RPM is very low, but I think nothing prevents the engine from spinning much faster than it does on a bike.
Unfortunately most hubmotors are built to spin slowly. They have high pole counts and thick laminations which mean core losses become large when the speed goes much above the nominal.

Re: Build a 5m rotor diameter

Posted: Jun 15 2019 11:50pm
by mettleramiel
Go to the forums on otherpower.com . They have tons of info on building your own wind turbine and even sell lots of the parts needed to do so.

5m blades is very large to start off with, though.