Diy mppt? - Page 9

Xringer · 12-30-10, 11:18 PM

That sounds like a Buck step-down converter..

Design of switch power supplies

fabieville · 12-30-10, 11:32 PM

he also stated that I definitely need to add the freewheeling diode in or the flyback voltage from the inductor will spike very high and will damage something.
So you would put the diode behind the inductor so that current only flows one way going to the inductor but not behind it?
With the diode arrow pointing towards the inductor?
Any size diode can use? I have salvage a inductor with a heavy guage wire plus 13 turns is that ok for my setup?

Xringer · 12-31-10, 07:10 AM

The Back-EMF diode should be fast and have the voltage and current rating to survive the current spikes and protect the MOSFET.

I don't know the 'Henrys' of your inductor, but as a guess, I would think a BYV28-200 might be a good diode to try..
BYV28-200-TAP - Vishay - BYV28200TAP - datasheet
If your inductor is really big, you will likely need a higher current diode..

fabieville · 01-01-11, 10:36 AM

Is it possible for me to also connect my wind turbine to the mini max too. What is the max voltage the mini max can intake? Is it 50 volt the maximum intake? I live in a low wind area so my wind turbine have never seen over 35volts.

Xringer · 01-01-11, 01:33 PM

Humm, minimax was designed for PV, but I wonder..

If you are in a low wind area... Maybe you don't want to load down your turbine/generator, until it gets up some RPMs.?.

So, once the RPMs are up, the FET fires.. But, the fly-wheel effect allows the turbine to keep it's speed.
If the wind really picks up, then the FET comes on more and maybe stays on if the voltage stays up..

The mini-max lets low wind spin the turbine without dragging down the RPMs.
But when the wind gets up and there is some real watts to be had,
the mini-max goes to work..

Does that sound reasonable?

fabieville · 01-01-11, 02:49 PM

It sounds reasonable.
The high voltage pulsing of the fet to my charge controller that is allowing it to be going between charge and full charge but not so rapidly as before since I have put in the inductor, I would say it is going between a 3-5 sec clicking rate between charge and full charge and sometimes more depending on the load that is on the battery at the time, the clicking is more smooth now. Will this be charging my battery efficiently comparing to just hooking the solar panel straight to the battery?

Also what do you mean by the fly-wheel effect allows the turbine to keep it's speed?

Xringer · 01-01-11, 05:10 PM

I can't say if you getting a better charge or not.?. You will have to do some testing
to find that out. Compare before & after performance.

fly-wheel effect is rotational inertia
Flywheel - Wikipedia, the free encyclopedia

fabieville · 01-02-11, 07:57 AM

The mini max is working wonderfully now the only problem that i am facing and its not really a problem, its more of an annoyance that i can live with, but i would be glad if i could eradicate it.
I realize that when the fet is in operation you can hear a little whining sound that sounds like its a frequency pitch and the sound changes depending on the sunlight that is reaching the panel.
What can i do to get rid of this sound?
I was thinking about using some filtering cap(s) on the output but please let me know what are your suggestions.

Xringer · 01-02-11, 08:22 AM

With the exception of piezoelectric effects (beepers etc) it's impossible to hear electrons moving in a conductor..

But, inductors and capacitors often react to current changes, with small mechanical movements. (acting like speakers).
They will vibrate or buzz at the applied frequency. (Normally 60Hz in the USA).
Are you using an inductor with a metal core? Those can hum like crazy.

If it's coming from the PV power wires, you can try adding some caps across the +&- lines.
That might smooth out the spikes (square waves) and make them less annoying.

My Morning Star TS-45 charge controller makes a high pitched noise
when it running in PWM mode. Lucky for me, it's down in the basement.

fabieville · 01-02-11, 08:27 AM

Its not from the inductor it was happening before i add it in so i am guessing its the fet and the pv panel already have the big cap across the output so what else should i do?

Also what can i do to protect the input and the output of the circuit if they are shorted?
Should i just add a high amp blocking diode that is above my PV short circuit current on both sides of the circuit?

12-30-10, 11:32 PM	#82
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	he also stated that I definitely need to add the freewheeling diode in or the flyback voltage from the inductor will spike very high and will damage something. So you would put the diode behind the inductor so that current only flows one way going to the inductor but not behind it? With the diode arrow pointing towards the inductor? Any size diode can use? I have salvage a inductor with a heavy guage wire plus 13 turns is that ok for my setup? Last edited by fabieville; 12-30-10 at 11:46 PM..

12-30-10, 11:18 PM	#81
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	That sounds like a Buck step-down converter.. Design of switch power supplies

12-31-10, 07:10 AM	#83
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	The Back-EMF diode should be fast and have the voltage and current rating to survive the current spikes and protect the MOSFET. I don't know the 'Henrys' of your inductor, but as a guess, I would think a BYV28-200 might be a good diode to try.. BYV28-200-TAP - Vishay - BYV28200TAP - datasheet If your inductor is really big, you will likely need a higher current diode..

01-01-11, 10:36 AM	#84
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	Is it possible for me to also connect my wind turbine to the mini max too. What is the max voltage the mini max can intake? Is it 50 volt the maximum intake? I live in a low wind area so my wind turbine have never seen over 35volts.

01-01-11, 01:33 PM	#85
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Humm, minimax was designed for PV, but I wonder.. If you are in a low wind area... Maybe you don't want to load down your turbine/generator, until it gets up some RPMs.?. So, once the RPMs are up, the FET fires.. But, the fly-wheel effect allows the turbine to keep it's speed. If the wind really picks up, then the FET comes on more and maybe stays on if the voltage stays up.. The mini-max lets low wind spin the turbine without dragging down the RPMs. But when the wind gets up and there is some real watts to be had, the mini-max goes to work.. Does that sound reasonable?

01-01-11, 02:49 PM	#86
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	It sounds reasonable. The high voltage pulsing of the fet to my charge controller that is allowing it to be going between charge and full charge but not so rapidly as before since I have put in the inductor, I would say it is going between a 3-5 sec clicking rate between charge and full charge and sometimes more depending on the load that is on the battery at the time, the clicking is more smooth now. Will this be charging my battery efficiently comparing to just hooking the solar panel straight to the battery? Also what do you mean by the fly-wheel effect allows the turbine to keep it's speed?

01-01-11, 05:10 PM	#87
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I can't say if you getting a better charge or not.?. You will have to do some testing to find that out. Compare before & after performance. fly-wheel effect is rotational inertia Flywheel - Wikipedia, the free encyclopedia

01-02-11, 07:57 AM	#88
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	The mini max is working wonderfully now the only problem that i am facing and its not really a problem, its more of an annoyance that i can live with, but i would be glad if i could eradicate it. I realize that when the fet is in operation you can hear a little whining sound that sounds like its a frequency pitch and the sound changes depending on the sunlight that is reaching the panel. What can i do to get rid of this sound? I was thinking about using some filtering cap(s) on the output but please let me know what are your suggestions.

01-02-11, 08:22 AM	#89
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	With the exception of piezoelectric effects (beepers etc) it's impossible to hear electrons moving in a conductor.. But, inductors and capacitors often react to current changes, with small mechanical movements. (acting like speakers). They will vibrate or buzz at the applied frequency. (Normally 60Hz in the USA). Are you using an inductor with a metal core? Those can hum like crazy. If it's coming from the PV power wires, you can try adding some caps across the +&- lines. That might smooth out the spikes (square waves) and make them less annoying. My Morning Star TS-45 charge controller makes a high pitched noise when it running in PWM mode. Lucky for me, it's down in the basement.

01-02-11, 08:27 AM	#90
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	Its not from the inductor it was happening before i add it in so i am guessing its the fet and the pv panel already have the big cap across the output so what else should i do? Also what can i do to protect the input and the output of the circuit if they are shorted? Should i just add a high amp blocking diode that is above my PV short circuit current on both sides of the circuit?