Open Source MPPT controller

[definitionofis]

if i might be so bold as to ask, perhaps it has been answered earlier, but i really would like to know.

where do you guys get your background in power electronics?  what books do your recommend on the subject?

I don't know any books to recommend. I am an amateur. My career path was not electronics.

I have been reading parts datasheets and listening to http://www.theamphour.com weekly and EEVblob at www.youtube.com/user/EEVblog
and www.youtube.com/user/ChipReportTV to catch up on thirty years of changes in electronics, since I last paid attention. www.allaboutcircuits.com is very good, also. I do specific internet searches for specific topics. This series is good on youtube: MIT 8.02 Electricity and Magnetism

[GoVertical]

http://www.mti.tul.cz/files/vke/Chapter_7.pdf

Not a book but very helpful

[boB]

if i might be so bold as to ask, perhaps it has been answered earlier, but i really would like to know.

where do you guys get your background in power electronics?  what books do your recommend on the subject?

 This series is good on youtube: MIT 8.02 Electricity and Magnetism

All sorts of good educational stuff on Youtube I have found...  Even the Indian stuff.

Of course it really helps to actually get your hands dirty as you guys are doing here !

boB

[GoVertical]

Hi, I order the parts before I understood Steve's circuit. I do not know if the Zeners will breakdown at 400 volts. The trigger signal is from the DC side at the buck converter input. L1 is from the AC side; single phase; from the PMA. If the SCR fires it will reset when L1 returns zero. Load could be a heating element so the PMA stator would stay cool. May be a possible solution for the input over voltage protection circuit. Comments welcome
 

[OperaHouse]

And when will L1 ever go to zero allowing the SCR to turn off?

[GoVertical]

Hi, maybe I should ask if the signal is AC from the PMA. I do not have a lot of experience with power electronic. This is why I am asking.

[definitionofis]

That is the similar circuit I gave you here, which uses the zener diode idea:
http://www.fieldlines.com/index.php/topic,146791.msg1009845.html#msg1009845

except I did all three phases, not one phase, and I added three tiny diodes for the DC gate power, instead of tapping gate power from the power DC side rectifiers, of your circuit.  I don't think I need a capacitor. I could add one.

Mine would take six SCRs (ignore the pairs) for 3 phases. Yours is three SCRs for three phases because it shares the DC side rectifiers.
I can locate mine outside, separate and away from my boost converter rectifier.

Not using the MC3423 controller has a disadvantage that the SCR gate current might be high, and my variable resistor might need to be higher wattage. MC3423 can use low watt resistors and it can do any voltage level without swapping different zeners. I am happy with the zener idea for mine, though. I have no wind to test it yet.

I think your 50K resistor might be too large. Maybe my SCRs are unusual, needing so much current. Check the gate current and be sure 50K will not drop too much voltage and mess up your zener setting.

My power is AC to turn off the SCRs on each cycle.

[GoVertical]

http://www.circuitstoday.com/scr-applications

Greetings, I have found a possible solution for the over voltage protection circuit. The circuit located at number 4 uses the AC to trigger the circuit. I could duplicate the circuit 3 times, one for each phase. When the SCR's are triggered the added resistive load would brake the turbine to lower the input AC voltage and the buck converter would continue to lower the voltage at the input capacitor of the buck converter on the DC side. I am not sure of the values required. D5 could be two 200 volt zeners in series for a 400 volt trigger. Comments welcome.     

[definitionofis]

I see that circuit separates the over-voltage protection from your power rectifiers, just like mine does. I think it would work.

D1 and D3 are doing full wave rectification for the gate signal. I think you should look at 3-phase full wave rectification to power the gates if you are going to do three phases. That is what I did with my equivalent three-tiny-diodes.  You would use six of those tiny diodes, plus extra zeners, and other extra parts, which I think are unnecessary, if you duplicated your circuit three times.

Plus I notice you would end up using the same six power SCRs (3x2=6), just like my circuit, if you did three of your circuit.

[GoVertical]

Hi, If I can get circuit working for single phase AC, this maybe a possible solution for a 3 phase configuration. Comments welcome.

[fabricator]

When the wind stops blowing.

[fabricator]

And when will L1 ever go to zero allowing the SCR to turn off?

When the wind stops blowing.

[boB]

It is kind of hard to tell sometimes when you have wires crossing, whether they are connecting or not.

Can you add tie-dots when they are connected ??

Also, it is kind of hard to tell if the resistors are high power dump loads or not.  Maybe you could
draw the power resistors larger or something if you don't have values assigned to them yet.

Looks like you are on the right track though.  I think.

boB

[GoVertical]

Hi, I tried to test the modified F&P with the OVP circuit. Because I modified the F&P stator I could not charge a capacitor to 400 volts to test to see if the OVP would trigger. I do have my moments.  RPM was about 600 and max voltage at the capacitor was about 350 volts with no load.     

Even if I add a 1:7 belt drive to the modified F&P I should be safe to road test with the buck converters.


I removed one of zener diodes from the OVP test causing the trigger voltage to be 200 volts. The OVP circuit triggered at about 200 volts and as I increased the RPM's the voltage at the capacitor remained at 210 volts. The load resistor was only rated at 1 watt and became very hot but the circuit still functions. I have to increase the wattage rating of the load resistor.

It looks like the circuit will work for my application, if used with a wind turbine and the buck converters, the turbine will brake because a resistive load is added when the OVP is triggered and the input voltage at the input of the buck converters will remain at a save value at higher RPM's.

R1 and R2 are the load resistors. I will work on a better drawing. No arc on a line when crossing another indicates a common point.


The circuit still needs more testing but I discharged the cap repeated the test a few times. The SCR's are firing and the circuit resets.

[definitionofis]

I still think my circuit is better because it does the same thing with less parts.  I never tested it yet though. I need a testing bench power supply.

[Bruce S]

I still think my circuit is better because it does the same thing with less parts.  I never tested it yet though. I need a testing bench power supply.

This is where a great old saying of "Proof is in the pudding" 
Get it hooked up to something to test it with and come back with the results.
In this RE world there really is no absolute "better" solution , just one that better suits the application and more importantly the availability of local parts.
Cheers
Bruce S

[fabricator]

I still think my circuit is better because it does the same thing with less parts.  I never tested it yet though. I need a testing bench power supply.

Lots of power supplies on ebay pretty cheap, radio shack also sells em cheap.

[definitionofis]

My circuit uses the same parts as the one GoVertical posted. In fact, it is the same circuit with less parts feeding the SCR gates.
It is built and hooked up. I am waiting for wind.

If GoVertical chose it, I would know if it worked.

Does anyone have a 10A 50V or more,  DC and AC power supply to recommend?  3-phase would be nice, too. Current limiting would be nice.

I suspect that is not cheap. Yes, I should check ebay.

[Bruce S]

My circuit uses the same parts as the one GoVertical posted. In fact, it is the same circuit with less parts feeding the SCR gates.
It is built and hooked up. I am waiting for wind.

You do know the Murphy's fist law of wind?
Once you put up a 'mill you'll not see wind for 3 days OR at the point where you want to bring it down for maintenance  .
 

[thirteen]

Or it will probably have the highest winds ever recorded
Truer words were never said
Remember this when the pieces are thrown in the pickup bed.

[definitionofis]

I have to wait until the trees lose their leaves before I will get a steady wind at ground level ... for a couple minutes ... a couple days per month.

I had a scary wind in May before I put up my blade. It was a one-day-a-year kind of scary.
It made me think a lot about my safety measures.

[GoVertical]

Hi, I tested the OVP circuit using a modified F&P PMA. I am satisfied it will work for the system to protect the mosfets on the buck converter I am using.

Parts used for OVP circuit:
SCR 800 volt, 8 amps, MCR8SNGOS-ND

Zener diodes IN5388BRLG 200 Volt 5 watt

Blocking Diodes FHA8TB60 , 600 volt, 8 amp, ultra fast recovery

R1 and R2 load resistors, 100 ohm 10 watt

Gate trigger resistors 2.2 K ohms

I am designing this for a VAWT, results maybe different if using HAWT.
When the OVP triggers the added load will brake the wind turbine and the buck converters will continue to lower the voltage at Vin until the OVP resets.
****************************
The next really problem that needs to be address is a dump load controller to protect the battery. Originally I was planning to use a discrete dump load controller circuit but depending on the duty cycle of the buck converters the voltage at the battery could greater than dump load circuit trigger voltage. Searching for solutions to this problem. Comments are welcome.