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Post Info TOPIC: Can a Buck converter improve turbine performance???
GoVertical


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Can a Buck converter improve turbine performance???
 

Hi, new data from test fixture.

 

Vin 30 vdc

Iin   0.5 Idc

15 watts at the input

 

Vout 12.32 vdc

Iout    2.3 Idc

28.3 watts at the output

 

Circuit operating at 30kHz @ 50% duty cycle.

PMA RPM 160

mosfet temp 82 degrees Fahrenheit 

 

The data is just ballpark values. I am confused by the results. There should be a lost of power not a increase. I may have a problem with multi meter reading current at the input. It would make more sense if the input current was about 1 amp. The meter is a cheap-O. The variable duty cycle switch does appear to be working.  There is a lot ringing in the waveform. I have to improve the inductor and reduce the reduce voltage spikes. Comments welcome

 



-- Edited by GoVertical on Friday 4th of May 2012 12:45:22 PM



-- Edited by GoVertical on Friday 4th of May 2012 12:45:44 PM

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sjh7132


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RE: Can a Buck converter improve turbine performance???
 

My 220uf is rated at 250v.



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Steve
GoVertical


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RE: Can a Buck converter improve turbine performance???
 

Hi, what voltage are rated for? I would to find a lower cost cap that would work at the input.



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sjh7132


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RE: Can a Buck converter improve turbine performance???
 

Still 250 watts into a cap, should have produced lots of heat.  My cap blew up with a lot less power.   But that theory does explain how the current can go in and not come out.  

 

Your input cap is huge compared to mine.  I'm only using 220uf on my test board.  You must be trying for very low ripple.



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Steve
GoVertical


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RE: Can a Buck converter improve turbine performance???
 

 

Hi, after watching the video a few times, I saw the output current raise to about 0.5 amps then dropped to the lower current value as I increased the RPM. I suspect this was the point when the input voltage exceeded the input max capacitor voltage value destroying the dielectric layer and creating a path to ground.  It is just a theory. Large value capacitors are very expensive. I did change the input capacitor to a less expensive configuration.  I am continuing testing with a 7800uf, 125volt capacitor and reducing the number of stators connected series. I will post results when available.            



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GoVertical


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Can a Buck converter improve turbine performance???
 

Hi, I was really happy the board did not burst into flames, I will recheck everything in the morning and I will wear my glasses.  I know the switch is working.



-- Edited by GoVertical on Thursday 3rd of May 2012 05:01:51 AM

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sjh7132


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RE: Can a Buck converter improve turbine performance???
 

GoVertical wrote:
 I am hoping I did not damage the mosfets when I solder them in the circuit.  

 When I build my boards I reflow the whole thing in the toaster oven.  When it comes out the MOSFETs are so hot, they don't work.  But they always cool down and start working.   When I replace them, I heat the whole thing with my hot air rework station.  Again the whole transistor is so hot it doesn't work for a minute.

I can pretty much guarantee, you are not torturing your MOSFETs worse than I do.



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Steve
sjh7132


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RE: Can a Buck converter improve turbine performance???
 

That's 170v x 1.5a = 255 watts in

12.34 * 0.3a = 3.7 watts out

That doesn't seem right.  Are those numbers correct?  Major loses is an understatement.  If you are missing 250 watts, it has to be showing up as heat somewhere.  Was the cap getting hot?

Looking at your circuit, given 1.5a is flowing in, I don't see how it can't flow out.  Where is that current going?  Maybe a meter isn't working correctly.



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Steve
GoVertical


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RE: Can a Buck converter improve turbine performance???
 

 

Hi, just a quick video showing test setup. With the PMA at 200 RPM the input voltage was 170 volts, 1.5 amps input current, 12.34 output voltage, and 0.3 output current. Mosfets measured 82 degrees Fahrenheit. The circuit needs major improvements.  The input capacitor is only rated for 100 volts and I have to check my inductor calculation. So there are major loses and the buck circuit is not working as it should but the test fixture is working. I am using a 12 volt deep cell for a test load. It does show the control circuit is working and the mosfets are turning on and off. It is a start. Comments welcome.   



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GoVertical


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RE: Can a Buck converter improve turbine performance???
 

 

Hi, I completed fabrication of analog MPPT test circuit. Video shows verification of selectable duty cycle with fine adjustment of each for each selected duty cycle, 10% to 50%. Next step is to test with PMA and battery test load. I am hoping I did not damage the mosfets when I solder them in the circuit.  



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