Using MPPT to regulate Wind Gen?

[hydrodane]

Originally Posted by Xthewater

If the wind generator controller is fried but power is still being produced it is likely AC which the MPPT can't regulate and you'll ruin the batteries. Wind gen controller typically rectifies the gen output to DC via diode bridge and regulates the output by shunting (controlled shorting) the power through resisters via electronic switching( op amp, transisters, zener diode, Hall affect or similar). The braking is done by shorting the output and magnetically locking the generator stator to the permanent magnet rotor.

An alternator does similar by rectifying the output to DC but regulates by controlling field voltage(excitation) via the 12v batteries, which is why if alternator output is disconnected from the batteries the alternator loses reference, goes full output and blows the regulator.

I am really impressed with some of the technical knowledge of the folks on this website. I am an avionics tech (boeing, airbus), and I have to admit there are few people even in my community that can match some of the fundamental explanation that some of you folks here offer accurately.

kudos.

ps...one day, I'll return to the sea

[Canibul]

Ya just gotta know how to ask the right questions, yuk yuk...

[Canibul]

Originally Posted by Xthewater

You would be seeing half the component of the AC sine wave on the DC function of the meter. Remember the polarity reverses with AC at the rate of 60 Hz.

Okay, thanks. I see what you mean.

So, to be sure I understand this...if I stick the same meter probes into the standard 120 V (nominal)AC outlet on shore power, with the DVOM mode on DC volts, it should read 60 VDC?

This makes me worry about the meter, actually. This is a fairly good one. I'd expect no display or an error message, or auto switching to the other voltage setting. It's not telling me that this isn't DC.

[hydrodane]

Originally Posted by Canibul

Ya just gotta know how to ask the right questions, yuk yuk...

[hydrodane]

Originally Posted by Canibul

Ya just gotta know how to ask the right questions, yuk yuk...

that really funny...reminds me of my old USCG boss, who would routinely say before any briefing:

"I have all the answers, now my aide will pass out the questions you are allowed to ask"

it was a nice ice breaker...(as his aide, myself, I knew how truthful his humor really was...lol)

[Frugal]

The nature of MPPT regulation is sampling the output amperage over a period of time ( ? seconds ). It requires a steady input for best results. My wind generator ( 400 watt, rectified 3 phase star configuration ) output varies with wind conditions and often fluctuates faster than the sampling rate of the MPPT.
I have connected my wind generator directly to the battery bank with a simple, switch operated relay, that shorts out the generators output.
The occasions when the wind generator provides above float voltage is very rare and I am reminded by the screaming wind in the rigging.
To automate the system a very simple volt reacting switch could be incorporated to energise the relay.
Cheers.

[Littlechay]

Originally Posted by Xthewater

You would be seeing half the component of the AC sine wave on the DC function of the meter. Remember the polarity reverses with AC at the rate of 60 Hz.

Oh yea! 60Hz? got a constant wind speed in your part of the world have you?

[Captain Bill]

Sunforce sells a wind generator with what they call and "MPPT" controller. I think technically it is simply a buck controller. The generator head can put out up to 70 volts of 3 phase AC. Rectification is done in the controller, not the head. The high ac voltage allows you to use smaller wires. The "excess" voltage is converted into amps and fed to the battery at the appropriate voltage for the state of charge. The amperage output varies with the wind speed. If one simply applies rectification and attaches directly to a battery then all you get for amps is what the system generated at the head.

[Xthewater]

Originally Posted by Canibul

Okay, thanks. I see what you mean.

So, to be sure I understand this...if I stick the same meter probes into the standard 120 V (nominal)AC outlet on shore power, with the DVOM mode on DC volts, it should read 60 VDC?

This makes me worry about the meter, actually. This is a fairly good one. I'd expect no display or an error message, or auto switching to the other voltage setting. It's not telling me that this isn't DC.

There's a DC component in the AC which the meter will see and not able to discriminate, but by switching to the AC scale you'll be able to see the full wave RMS voltage. Keep in mind the meter is showing the RMS (Root Mean Square) of the AC not peak to peak where as in DC scale on a DC source it shows full voltage. Sounds confusing but AC is in constant flux so there's an averaging that takes place with multimeters aka VOMs. This is where an oscilloscope comes into use for much more accurate measurement and not really necessary here.

[Frugal]

Hi Captain Bill.
Your comments indicate you get a better output by running the alternator at a higher voltage ( via an mppt type device ).
My experience with the cheap Chinese Air X look alike is that the voltage generated is sub 13.4 volts till the wind speed is around 14 knots.
It's output rises by about 1.5 amps per knot of increased wind speed.
The blades cavitate at around 33 knots with the output in excess of 30 amps.
Do you find the higher alternator voltage gives you a better yield?
Cheers

[Canibul]

Maybe I need to get a little better educated on troubleshooting this thing. It, and the IOTA 55 charger, are the last bits of the boat still to be repaired after our lightning strike.

[Littlechay]

No affiliation but I like the diversion charge regulators for wind turbines - many brands out there. Tough and long lasting, perhaps not quite as efficient of some of the fancier methods but less likely to fail you.

They work well from a charging point of view and don't let the turbine spin out of control. Add a simple short-circuit switch and you have an effective electric brake. Still tie it down when the breeze gets up.

Chris
--
SY Morgane
http://www.tweedsworld.com

[dlockhart]

Ahhh, you think the two things are the last things to be repaired after the lightning strike. I thought much the same and then just now spent an additional $8000. that reared it's ugly head when we beached to scrape and change sail drive seals, wasn't any sail drives left to reseal. Just trying to soften the blow for ya. Still love your blog and will run into you somewhere someday on the water.