Hi All.
I'm new at the forum and taught it was a nice place to discuss this topic.
Many of you probably know the award winnng 555 design of Michael Davis at:
http://www.mdpub.com/555Controller/Honestly i had never seen a 555 being used in such a clever way. Which is why i choose to try his model before getting into the RossW approach, which i also find very interesting.
This is the Schematic:
http://www.mdpub.com/555Controller/images/555ChargeController.jpgSince i will be building a 48 volt version of the 555 controller circuit, it would be great to hear some expert opinions on the additional calculations i did in order to make it work:
1) The voltage regulator i will be using will be a LM2575, which can take arbitrary DC inputs from 7V to 60V. This solves the problem with powering the circuit and works within the ranges handled by both the turbine and my battery array.
2) In order to set the charge/dump thresholds i will set R1 to 34.3K and R2 to 18K. Meaning start charge at 54 V and Dump at 58 V.
3) Obviously, the relay will not be a standard car (12V), but a 48V version.
4) I think the rectifier bridge at the 3-phase input will be enought protection against "reverse voltage", but somehow i also have my doubts.
5) The system´s GROUND reference will not be -12VDC, but -48 VDC from the negative poles of the batteries and rectifiers. I have no idea if i should add some more ohms before hitting ground at all appropiate places. Any thoughts?.
I´m calculating this with the stuff i remember from university... and i´m a software architect, not an electronics engineer hahaha... hence the warning and posibly silly questions.
Aside from my calculations and perspective, would any of you have any important remarks or ideas?
I have also written to Mike asking for his toughts, i will share them here if he answers (let´s hope he does).
Thanks!
Pedro
PS: I´m a 30 year old kid building a turbine with another 60 year old kid (my dad) LOL.. and we are really enjoying this. So far our 2 kilowatt LIFT VAWT reaches 60 Volts AC @ 150 RPM without an issue
... all we need now is a working charge controller... we tried a HAFEI PWM unit but sadly it is designed to ask for a $#|+load of torque from the turbine, rendering it useless. So we taught of a "less sofisticated" approach to just charge what´s really available.