Homebrewed Electricity > Wind
Help needed on a Breezy type grid tied induction turbine
JW:
Try this email ****@otherpo*er.com ask for Danf
Kyle:
Done. Fingers crossed.
Kyle:
UPDATE:
I have changed to a single phase 750 watt motor. I have new, larger blades. My gear ratio is 11:1. I have a small controller which opens the relay at 15 mph (anemometer on tower) and disconnects during grid loss. Depending on wind gusts, it is generating 300 - 600 watts per my plug in watt meter.
My problem is that it doesn't start producing power until 20 mph wind. I would like to change this to 10 mph. Since the torque of the motor is fixed, Which of the 3 variables I have to play with would bring me closer to the 10 mph cut in speed? Increasing blade length, changing blade angle (currently 5 degrees) or changing gearbox ratio.
https://www.youtube.com/watch?v=m_FQv6Irlp8
joestue:
I would reduce the voltage to the motor and see if you can start producing power closer to 15mph which is presumably above the 60hz cut in speed as determined by the gearbox and number of poles.
A 750 watt motor will have a no load power draw at nominal line voltage and frequency of at least 200 watts. So you need at least that much shaft power before you get anything out of it. Reducing the line voltage to half of nominal, should reduce the no load power loss to more like 50 watts, and on a 750 watt motor it should work as a generator at half the voltage up to about 100-150 watts output before it runs away.
two speed dual winding motors are readily available from hot tub pump motors. they are on the order of 1-2hp at 3600 rpm and .15-.3hp at 1750 rpm. the last one i pulled apart had 4 separate windings, and two capacitors, so that you can change between the speeds with just a single spdt switch. these motors are nearly ideal for a wind turbine because they are already designed for a cubic load.
Another option for wind turbines (again due to the cubic load) is to take a 2 or 4 pole motor and reverse half the windings to get a 4 or 8 pole motor. The problem is the motor wasn't designed for it and you have to reduce the voltage to the motor to prevent the core from saturating (because there is no room between the coils for the flux to flow where it wasn't originally intended to go). For the cubic power curve of a wind turbine this isn't nearly as much of a problem as it is for say, a lathe or milling machine spindle because at half the rpm you only have 1/8th the wind power, you only need one half the voltage to the motor (An induction motor's torque follows voltage squared.)
Reducing the voltage also reduces the no load power loss.
A lot of motors are wound with 2 wires in hand, so you can rewire it to get the voltage reduction you need at the higher pole count without using transformers. Another option is to find a 120/240v motor and reverse half the coils and connect it for 240, run it on 120vac. for high speed connect it for 120vac. for each coil that needs to be reversed you need a dpdt relay, so you may find the complexity to be undesirable.
Or don't mess with the motor and change the gear box.
another option would be two gear boxes and two motors. i would run a 2:1 gear box off the existing motor to drive another one. a clutch in between is logical
Kyle:
Okay, that makes sense to me. Are you suggesting something like this?
https://www.menards.com/main/tools-hardware/power-tools-accessories/routers-accessories/router-speed-control/80820/p-1444421810442-c-10087.htm?tid=6330182982034452332&ipos=1
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