You want comments, but won't listen to advise. Will try one more time, read this link - http://www.simonbramble.co.uk/dc_dc_converter_design/buck_converter/buck_converter_design.htm

Seems like you want a pat on the back more than help.

 

http://www.youtube.com/watch?v=-UalBvsoTuE&feature=youtu.be


Hi, The link suggested is for a resistive load, I am still searching for a circuit that uses a PMA for Vin and a 12 volt battery as a load. I am just posting the results of the project to date to keep myself motivated.

New video of circuit operation, I am manually operating the PMA.
12 volt battery as load. Waveform is Vs of N channel mosfet. Vin = 20 volts at highest RPM, current into battery 0.75 amps at highest RPM.

The waveform is not what I expected, at this time I am unable to explain results. It looks like I have to inverter the control signal. comments welcome

 

Do you even read the answers to the questions you ask? Are you related to another of our members, named Loosewire?

You do know that you have gone about this project in a very haphazard way ,correct? To illustrate-

You have made a great PMA, of probably to much power.

Trying to turn it with blades of too small an area to get a good output.

Trying to design a converter without knowing the parameters of the output of the PMA.

Trying to make a converter from individual components instead of using the correct IC.

Experimenting on a self designed "converter" using voltage and amp ratings much smaller than your "unknown" real life values.

Trying to charge a "12 volt" battery with 12 volts, when "12 volt" batteries are not in real life 12 volts.

Asking questions and ignoring every answer and not even attempting to help yourself on 'your' project! I know what you want is for someone to design a circuit for you, but why would they if you won't listen?

This is not the way a project should be planed or attempted.

 

Hi, this is a first attempt and a learning experience. This is the project section.
If anyone can benefit from my mistakes, great.

 

Greetings, using a isolated power supply and FOD3180 does work. I am using a blocking diode between the inductor output and the plus terminal of the 12 volt battery. The gate driver is triggering a N channel IRF540 in a Buck circuit configuration and is charging the battery, current about 1 amp. Then I replaced the battery with the 50 watt halogen light and the circuit was able to illuminate the light after I adjusted the duty cycle, current max about 4 amps. I was manually operating the PMA. The next step is to drive the PMA with the drill press to determine how the circuit behaves at a higher RPM.

Chapter 4. page 69

http://etd.ohiolink.edu/view.cgi?acc_num=akron1320692738

Isolated power supply with FOD3180 gate driver. N channel Buck converter using a IRF540 mosfet. Bottom wave form is gate of mosfet, top wave form is source of mosfet.
Input voltage max about 40 volts. Output current varies depending on duty cycle. Circuit still needs improvement but it is working. Input voltage is from a permanent magnet alternator and is being manually operated. Comments welcome.

http://www.youtube.com/watch?v=xcRBW2gZHIk&feature=youtu.be

 

The next step is to drive the PMA with the drill press to determine how the circuit behaves at a higher RPM.

You should see the emf increase linearly with rpm. It's hardly worth doing the experiment except for the satisfaction of seeing that happen the way it's supposed to. You'll have to watch the drill press rpm. If you load your alternator at all, that load ultimately is seen by the drill press and it may slow and heat up under load. Keep an eye on the motor temp, so you don't ruin it.

If you map out voltage produced by your alternator versus load resistance, you'll also see that the point of peak power moves toward a higher load resistance as the rpm goes up. The peak output of an alternator is always where load impedance (simple resistance for a purely resitive load) matches alternator impedance. The peak moves up with rpm because your coils have inductance, and their impedance goes up linearly with rpm also. So you can get more power at higher rpm, but not under all circumstances. Load must match source.

 

Hi, I have limited understanding of the MPPT algorithm requirements. Testing a analog circuit will help me better understand the MPPT requirements and verifying the circuits operation will reduce errors when the microcontroller is added.

Circuit update: currently constructing new test circuit. Added fixed frequency timer and one shot 555 to provide stability for duty cycle adjustment. Updated test points and added Vin discharge push button, also included on/off circuit power switch. Comments welcome.

 

You're diagram shows a 7812 attached across the 12v battery. A properly charging battery might present 15v at the poles, or 3v of reverse voltage to your regulator. I forget how much it can take, but that seems like a bad idea. Why is the 7812 there?

 

Hi, I need a regulated 12 volts for the IC’s Vcc and to supply the isolated power supply for the FOD3180 gate driver. I am searching for a circuit that would work using Vin, but the input voltage can change from a very high voltage to zero volts depending on the RPM.

 

Sorry, I misread your diagram. I thought you had the +12v output supplying power to the battery, but not so.

 

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.



http://youtu.be/FHYqMFLD7rc

I connect four IRF510 in parallel, this is a first attempt and is just for the learning experience of paralleling mosfets. My PMA has inputs and outputs on each stator so I change the internal resistance of the PMA. The variable duty cycle of the circuit will aid in testing of the different internal resistances of the PMA. I will post results when available.

 

Video of test circuit
http://www.youtube.com/watch?v=RqBQzoq_ctc

Hi, I configured the PMA using just 2 stators to form a 3 phase star, 8 coils per phase. Phase to phase resistance = 9 ohms.

Rotor RPM_____Voc DC
100____________15
200____________30
300____________45
400____________60
500____________75

Rotor RPM_____Vin DC____Amps in____Amps out
100____________16.5______? _________0.2
200____________27.3______0.2________1.0
300____________28.8_____ 2.0_________5.0___Vout = 12.8Vdc

Free wheeling diode temp = 82 degrees F
50% duty cycle
test fixture limit 300 RPM using load

Vout = 12 volt deep cell test load
measurements ball park , 60 Watts appears to be the limit of test fixture under load.

I have to remove one stator and rotor and then I will be able to road test. Search for ideas on how to limit voltage to 100 volts at the input to protect circuit. Comments welcome

I am do not know how to measure current with a O-scope. I am researching the method.

Maximum current output without using the circuit is 2 amps. The circuit is definitely a benefit.

 

Greetings, I have made a lot of progress on the wind turbine buck converter project. I have successfully tested a 5 amp buck converter using a 20 kHz controller board with a manually adjustable variable duty cycle. The duty cycle can be switched to 10, 20, 30, 40, and 50 percent. Then a variable resistor is used for fine tuning of the duty cycle. The controller board can drive four 5.0 amp buck converters. Each buck converter has it own bridge rectifier. This was the only to increase the current output to a max of 20 amps with the parts I am using.

The permanent magnet alternator I am using can produce about a volt per revolution. The input capacitor is rated at 450 volts. I am searching for away to limit the input volts to 400 volts. I have very little power electronics experience. If anyone has a solution it will be greatly appreciated.

I have started working on PCB

 

What's the problem with the 450v cap?

Your perm mag alternator is rectified to pulsing DC, so what is the max DC voltage of the peaks when the thing is running at full speed?

 

Hi, the problem is I will have to add a belt transmission to increase the RPM of the permanent magnet alternator to achieve useable power at average wind speeds. I can fabricate the transmission. If there are wind gusts the input can exceed 450 volts.

 

I've spent time wrestling with the better way to design such a thing. I believe choosing more windings (higher gauge wire, lower operating current) and maximizing the diameter of the alternator, are two better ways to match the power source to the load than introducing a mechanical transmission.

The latter has a guaranteed loss of several percent at least.

But there are also losses due to using finer wire and in having a higher coil inductance due to more loops. I think these are less than the transmission loss at low rpm, but the inductance problem increases at higher rpm. Maybe that's an OK thing, since you need to dump power at high rpm anyway and you don't care much about efficiency at that point.

I'm not claiming to know the answer, only that I have a grasp of the question.

 

Hi, I am limited to what I can fabricate. The largest diameter is 10 inches. I can stack the stators and rotors and connect the stators in parallel to lower the internal resistance and reduce the cut in RPM. But that creates a new problem. The PMA becomes to heavy. Using the buck converter solves the internal resistance problem and adjusting the duty cycle allows the turbine to run at a higher RPM and prevents stalling. It also allows you match PMA to the turbine blade performance more easily. The last problem to be solved is to find away to limit the input voltage to under 400 volts. Would it be possible to some TVS diodes to solve the problem?

I completed the PCB for the power modules.

 

A mechanical brake or current dump (eg. water heater) are common solutions.

Can you arrange some way to maintain a minimum load? I don't think you'll get voltages that high once a load is attached. You should, by the way, map out the I-vs-V curves for your windmill at different RPM. Very helpful data for designing and optimizing.

 

Told him that both in this and his other thread. Still don't understand why make ~400V to drop it down to 12V(14V).

 

I'm sure he's wrestling with the same problem all windmills suffer from: If you design for 5-10 mph wind, then you have a big problem at 50 mph. if you design for even just 20, you've got nothing at 5. It's just an unavoidable consequence of the physics involved, that the power available goes up with the cube of wind speed. That cube factor makes for an engineering challenge.