DC/DC with MPPT for solar panels

[iw2fvo]

Good day,
I will like to experiment solar panels ( PV ) using a DC/DC converter with the MPPT Max Power Point Tracking. I did plan to use a PIC Micro PWM for this purpose.
Is there any idea or a sample code to be used as a reference for the DC/DC with MPPT ?
Any help is appreciated.
Thanks
Ambrogio
North Italy

[mackrackit]

All you need is something like this.
http://www.national.com/mpf/LM/LM2588.html

[iw2fvo]

Hi,
I saw the national componed suggested by you.
It is a general purpose switcher and it is very good.
The thing i would like to implement is the MPPT in order to get the PV maximum efficiency in any momemt of the daylight condition.
I am really searching for a sample code in order to implement the Max Pwr Point Tracker and a DC/DC switcher program using a PIC pwm.
Thanks
Ambrogio

[jderson]

Type "sun tracking" into the search tool.

[iw2fvo]

Type "sun tracking" into the search tool.

I am really searching for a basic code that allows to maintain the max power output from a PV. So the V*I ( pv parameters) is to be maintained to the max . I plan to play with the duty cycle of the DC DC in order to "track" that max power out from the PV.
I do not want to track the sun position during the day by rotating the PV.

Thanks.
Ambrogio

[ScaleRobotics]

Pic Assembly code example - scroll down page to MPPT-4.2:
http://www.drgw.net/workshop/MPPT/mppt.html

http://www.electro-tech-online.com/m...-picbasic.html C code

http://electronicdesign.com/Articles...ArticleID=6262 LTC1149

http://www.solarbuildings.ca/c/sbn/f...for%20MPPT.pdf nice paper on subject

Hopefully one of these will help. Keep us posted on your project. I have an interest, as I have a couple C-40 charge controllers for this system. MPPT would be nice!

[ScaleRobotics]

One more link http://www.wseas.us/e-library/transa...008/27-545.pdf

And some good information, if you look hard enough here. With some C examples in the .rar files https://sites.google.com/a/l2na.com/...me/attachments

[iw2fvo]

Thanks for the links you have sent to me.
It is a lot to read and very interesting.
I would like to submit a concept for having reply and discussion:
All the documentation talks about the peaking of the PV power output by control the V*I product at its maximum possible level.
What do you think if the program will adjust the dc_dc duty cycle just to peak the battery current at max level ? The target is to inject the max possible current in the battery for recharging and so, why do not try to get it at its maximum ?
Thanks
Ambrogio

[ScaleRobotics]

Hello iw2fvo,

I have not really read the documentation I linked yet, (really just browsed it). You might be saying the same thing, but it is my understanding that MPPT senses battery voltage, calculates what charging voltage is required, based on that, converts PV voltage and current to match what the battery needs for charging. This would be the highest current available to charge the batteries.

For instance,
Assume your battery is low, at around 11.5 volts. A MPPT takes PV output at 16.9 volts at 7.1 amps and converts it, so that what the battery gets is no longer 7.1 amps at 12.5 volts, (which standard charge controllers will do) but 9.6 amps at about 12.5 volts using MPPT. If you bring the amps up higher, you drop the voltage, and if you drop the voltage much lower, you won't be able to have the current flow into the batteries.

Here is one last link that explains in very general terms how MPPT works. It is not great, but I have not found a better general explanation. http://www.solar-electric.com/charge_controls/mppt.htm

[iw2fvo]

Hi Scalerobotics,

That is a very good site. Thanks.
I do have to learn a lot of things ! and then I have to make a breadboard and I have start to write the code for the PIC micro.
Thanks again
Ambrogio
IW2FVO

[ScaleRobotics]

I do have to learn a lot of things !

Me too. But that's what this forum is all about! MPPT is pretty complex and it's use is specialized. That is, the main use would seem to be power generation such as Photovoltaics, and wind power. Things that give varying voltages, where you want to use every extra mA of power. Most articles seem to be within research, and engineering colleges, rather than people doing such things in their garrage. But I am sure more people are doing just that. It is somewhat a new technology, so within a year or two, there will be others documenting more on how its done, I am sure.

I did a search on open source mppt, and a pretty detailed project, but not much explanation is given here: http://solarcar.stanford.edu/blog/news/455 go to the download section. You may be able to ask Sasha about a paper on the MPPT portion of the solar car project. If you get any more information, please share it. It looks like they plan to release more information later on the subject.

Pretty cool pictures of the car at the very bottom of the link.

[iw2fvo]

Very nice lab: I would like to have one !
I contacted Sasha just now.
I will let you know.
Thanks
Ambrogio

[ScaleRobotics]

A few more links for you:
Arduino MPPT: http://www.timnolan.com/index.php?pa...-solar-charger

The above author's Home Power Magazine article about MPPT http://www.timnolan.com/uploads/Ardu...%20article.pdf

CCSinfo forum: http://www.ccsinfo.com/forum/viewtopic.php?t=30330

One more paper about a Pic microchip system http://seniord.ece.iastate.edu/dec08...esentation.pdf

[Heaven Net]

I'm working on a boost DC/DC converter to charge a 12V sealed lead acid battery from a solar panel at the moment. Basically, I've replaced ... I have however an old articel that descripes how to do a MPPT with a LTC1149. ...
www.edaboard.com/ftopic99450.html


Discussions and Opinions about dcdc converter - search results on edaboard.com. ... No new posts, Electronic Elementary Questions · Solar Panels 9v ...
www.edaboard.com/search,dcdc-converter.html

[ScaleRobotics]

Looks like I missed Microchip's application note on MPPT AN1211

http://ww1.microchip.com/downloads/e...tes/01211A.pdf

and missing wire in their schematic:

http://www.microchip.com/forums/tm.aspx?m=487707

[ScaleRobotics]

Microchip has a micro inverter reference design with MPPT here:
http://www.microchip.com/stellent/id...cName=en551429



Key Features:

• Peak efficiency of 95%
• Output current THD < 5%
• Power factor >0.95
• Maximum power point tracking
• Grid voltage and frequency tracking
• Protection against various current and voltage faults
• Night time power consumption <1W
• System Islanding to detect grid failure
• Full Digital Control

Specifications:

• Micro Inverter for individual PV Module up to 220W
• Wide PV Panel voltage : 25V to 55V DC
• Maximum Power Point Tracking voltage: 25V to 45V
• Maximum DC short circuit current : 10A
• Grid Frequency range :

47 – 53 Hz for 220V systems
57 – 63 Hz for 110V systems

• Grid voltage range :

90V – 140V for 110V systems
180V – 264V for 220V systems

[clark86]

Hi People

I need help with my final year project here too.
My project is to design a power optimizer which need microcontroller to program MPPT to control the dc-dc converer.
Things that i need to source out are the microcontroller (which i've brought microchip PICkit 2 starter kit), dc-dc converter (no idea wht is compatible to microchip starter kit), voltage and current sensor.
Can anyone suggest what is the dc-dc converter you are using? And is there any consideration i need to take note of when building power optimizer?
Sorry i am quite noob with this.

Clark86