Author Topic: Boost converter, pwm and mppt (Read 14544 times)

willib · « **Reply #33 on:** November 28, 2006, 09:55:15 PM »

On second thought i've decided against it.

i dont want to be held liable for any damages , done to any device , or anybody/anyone.

what was i thinking!

stephent · « **Reply #34 on:** November 28, 2006, 10:05:49 PM »

willib inserts un-needed disclaimer above....

What you were thinking is as you usually do--you like to share your knowledge, and even resources and there's nothing wrong with that at all willib.

Stephent tips hat to Willib.

willib · « **Reply #35 on:** November 29, 2006, 09:07:41 AM »

this is what i want to do next

willib · « **Reply #36 on:** November 29, 2006, 11:10:09 AM »

its a pic to pc RS232 connection , which i could use my laptop to collect the data

it stores the data in a text file on the laptop

sorry for the look of the jpg the whole thing would not fit in one .jpg

i can use the 16F877A in place of the 18F452, and use two transistors and some resistors to emulate the MAX232

richard · « **Reply #37 on:** November 29, 2006, 01:58:11 PM »

Take a look at http://HTTP://Tech.group.Yahoo.com/group/tunecharger/

AequalB · « **Reply #38 on:** November 29, 2006, 02:40:27 PM »

AequalB · « **Reply #39 on:** November 29, 2006, 03:01:54 PM »

this may look better

http://www.otherpower.com/images/scimages/3237/boost_circuit2.JPG

AequalB · « **Reply #40 on:** November 29, 2006, 04:42:04 PM »

Or...

willib · « **Reply #41 on:** November 29, 2006, 11:42:45 PM »

A=B ,

what happens when the upper part of the phase is negative, and the lower is positive?

the body diodes will conduct , and short the alt for that part of the cycle,i know ! i allready suggested a similar scheme to Flux..

btw , why are you using two fets stacked like that ?

the source dosn't like being that far from ground because it is harder to turn it on

AequalB · « **Reply #42 on:** November 30, 2006, 01:59:35 PM »

willib

Why are using two fets?

It is inevitable in circuits of an alternating current.

http://www.otherpower.com/images/scimages/3237/o.JPG

AequalB · « **Reply #43 on:** November 30, 2006, 02:07:49 PM »

It`s working:

willib · « **Reply #44 on:** November 30, 2006, 11:19:03 PM »

Thats an interesting circuit!

i did not know the lead between the fets was ground.

i'm wondering whether or not you could connect that lead to the center tap of a wye connected three phase alt?

that sort of looks like a sync rectified boost converter

how would that look in three phase?

AequalB · « **Reply #45 on:** December 01, 2006, 02:15:37 PM »

it`s simple...

willib · « **Reply #46 on:** December 01, 2006, 08:54:05 PM »

richard your link dont work?

willib · « **Reply #47 on:** December 01, 2006, 09:26:59 PM »

i got the RS232 connection to work!!

it took two hours and 8 mins

this is soo cool

i can now read the data comming from the PIC16F877A at 9600 baud , i havnt tried a higher speed yet

i coppied the program from the pascal Pic USART library

loaded it into the PIC

i used two transistors and two resistors to emulate the Max 232 chip , and a little fiddling around and i'll be damed but everything i sent to the pic came back..

which is what it was supposed to do..just resend everything it recieved .

when i finish with the program ,i could read analog voltages such as battery voltage , current from the hall sensor , RPM from a hall switch , and hopefully wind speed , and log everything on the laptop.

domwild · « **Reply #48 on:** December 12, 2006, 01:41:55 AM »

Willib,

Great stuff! Have you ever tried using a Picaxe? I do not wish to be seen to pushing a particular product, but RS232 coms would not have cost you two hours of sweat and tears. PWM is supported also. The BASIC used in the Picaxe is easy to learn. In fact you program the Picaxe through the serial port and can get data out via the "debug" statement. Sorry to hear you suffer from Pascal and assembler.

Because it is a smaller PIC, it does not offer floating point, only integer arithmetic.

I do not have a black belt in electrickery but haved followed the MPPT discussion. Am amazed commanda is not in the loop at the moment; she is also working on this holy grail of wind harvesting and she definitely has a black belt. We all have other committments.

So much to learn, so little time!

commanda · « **Reply #49 on:** December 31, 2006, 11:19:00 AM »

Hi All,

I'm back.

As Dominic says; other commitments.

Willib,

Glad to see you've finally upped the pwm frequency to something more reasonable and got some ferrite cores.

I'm sure I pointed this out before, but I'll do it again. What do you have in the way of a driver circuit between the output pin of the Pic and the gate of the fet?

To charge and discharge the gate capacitance in a timely manner (nanoseconds, not milliseconds), you need a peak drive current capability in the order of one to two amps. Also, the pic runs off 5 volts. Unless you're using logic level input fets you'll need a level translater to get the gate drive voltage (typically 12-15 volts).

MPPT; maximum POWER point tracking. Power is volts times amps. For all practical purposes, you can treat the battery voltage as a constant. Therefore, you can use the battery current as the target variable, and increase/decrease pwm to get maximum battery current, which will also be the maximum power point. Just to repeat what was said earlier in this thread.

Amanda

willib · « **Reply #50 on:** January 17, 2007, 06:15:35 PM »

Amanda , welcome back!

i didnt see this earlier

i am using a logic level FET IRF3703 very low RDS(ON).

the PIC is driving the FET directly

i am looking for an appropriate Fet driver ckt though

any ideas?

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