TheBackShed.com

Forum Index : Windmills : f&p with mppt

Author

Message

bennyspoon
Newbie

Joined: 15/02/2014
Location: Australia
Posts: 5

Posted: 11:52am 17 Feb 2014

Copy link to clipboard

Print this post

greetings fellow fiddlers. i've just signed up and had a search on the forums here.can't find anything so i thought i'd ask.

i'm wondering if anyone has used a smart drive with an mppt reg like the midnite classic. as the voltage on a paykel gets quite high when unloaded i wonder if the size of the stator is as important, apart from having to include something like their clipper.

any thoughts?

ben.

Don B

Senior Member

Joined: 27/09/2008
Location: Australia
Posts: 190

Posted: 09:32pm 18 Feb 2014

Copy link to clipboard

Print this post

Hi Ben, and welcome to the forum.

I am not familiar with the "midnite classic", so I am not sure of what it professes to do.

Trying to track the maximum power point of a wind turbine is a difficult exercise, and devices that do this for a solar panel (if that's what a midnite classic is) will not really help.

There are two ways to track the maximum power point for a wind turbine. One way involves an upstream wind speed sensor coupled to a controller that can adjust the alternator voltage, and hence the load, so that the turbine speed is allowed to change in direct proportion to wind speed changes. This arrangement permits a constant tip speed ratio to be maintained (a TSR controller). The set tip speed ratio can then be trimmed to a setting that delivers maximum power at any given wind speed within its operating range.

The other way does not involve upstream wind speed sensing, and has the controller continually making incremental adjustments to the alternator voltage. It then checks to see if the most recent change improves the output. If it does, then it will make a further adjustment in the same direction. If it does not, then the controller will change by an increment in the opposite direction. This type of controller is called a "perturb and observe" or P and O type.

Either type of controller will have to be capable of efficiently transforming the alternator output voltage to the (presumably relatively constant)load voltage. It must also be capable of operating at the maximum prospective power output of the
turbine, at which time the turbine voltage will also be at a maximum.

There have been some tracking devices described in this forum in the past that might give you a starting point.

I hope that this helps.

Regards

Don B

electrondady1
Senior Member

Joined: 12/02/2009
Location: Canada
Posts: 208

Posted: 02:43am 19 Feb 2014

Copy link to clipboard

Print this post

it's a windmill mppt and charge controller

http://www.midnitesolar.com/

Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4406

Posted: 12:43pm 19 Feb 2014

Copy link to clipboard

Print this post

I just had a quick look at their blurb, and it appears the Midnight Classic can work both ways.

They have something called "wind track" where you need to enter 16 operating points manually.

And there is their "dynamic mode" which seems to be the classic perturb and observe function.

Either should work, and each has its own advantages and disadvantages.

Over voltage is always a concern with any wind machine, especially in storm conditions or running completely unloaded.
Various solutions are possible, but you need to think the whole issue right through and come up with a workable control strategy such as furling, and voltage clipping and/or a dump load.

Cheers, �Tony.

bennyspoon
Newbie

Joined: 15/02/2014
Location: Australia
Posts: 5

Posted: 12:50pm 24 Feb 2014

Copy link to clipboard

Print this post

thanks for the replies fellas,
my question was more aimed at the smart drive side of the equation, pertaining to when a smart drive is used with an mppt type reg, the voltage would be higher than battery voltage. would then, the stator wire size and wiring configuration have as great a bearing as when used with a conventional pwm type reg and locked to the specific battery voltage.

ben.

Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4406

Posted: 01:43pm 24 Feb 2014

Copy link to clipboard

Print this post

The advantage of MPPT is that with a pretty flat battery and only light wind, the battery cannot overload the wind turbine and pull the turbine rpm right down where the blades stall.

The wind machine will be optimally loaded where it produces whatever maximum power output it is capable of, under the prevailing wind conditions.
The problem isn't the smart drive, or how the windings are connected, or the output voltage.
The problem is correctly loading the blades aerodynamically, and having the blades run at the most efficient rpm for their diameter, number of blades, and blade pitch.

Once you have achieved that, it really does not matter (within reason) what the F&P output voltage is, you can use a PWM voltage converter, controlled by the MPPT circuit, to convert the rectified F&P output voltage to the battery voltage.

Cheers, �Tony.

Print this page

To reply to this topic, you need to log in.