Wind tunnel, toy mill, mppt controller

[commanda]

Thought it was about time I got back to some of this, and bring you all up to date with what I'm doing.

I mentioned a long time ago I had a wind tunnel at work, but it was really too small for much practical application. I've also been working on an mppt system. I really need a working wind generator to progress the mppt. And Jaycar now sell a toy wind generator kit, which makes a whole 10 volts at 100mA. So I put all these things together, and this is where I'm at.

Here's a few photo's.

 We use the wind tunnel to calibrate air velocity sensors for ventilation systems in coal mines. It's about 12 inches square. The big blue box is the motor speed controller.

The pcb is the prototype mppt controller. For those that can follow this, here's a brief explanation. A 4046 PLL is used as an oscillator to modulate the control voltage for the pwm. The 3 small op-amps give a signal derived from the generators output power. The first is a current amplifier, the second is an OTA analog multiplier (current times voltage = power), and the third is a differentiator. The 4046 includes a phase comparator. The 2 inputs to the phase comparator are the modulation signal and the power signal. The output of the phase comparator is integrated & becomes the dc control voltage for the pwm. There's also an input from the tacho, to quickly push the control voltage in the right direction as the wind changes.

So, if the pwm modulation and the power feedback signal are in phase, we keep increasing the pwm control voltage. If they're out of phase, we decrease the pwm control voltage.

Apart from some basic functional testing, to verify parts of the circuit behave as expected, I've yet to do any full-blown testing. Anyway, I've yet to actually build the pwm circuit, and a fet. I'll probably just run the wind generator up by itself, and plot some figures. Then use the fet as a load, and verify that it gets to the mppt point for each applied windspeed.

Amanda

[willib]

congrats , i was hopeing somone would do what you are doing .

needless to say i for one will be VERY interested in any progress that you make .

please keep us informed.

william

[amiklic1]

Nice project. Can you post some schematic of that MPPT controller? How powerful it is, and what to do to make it usable with higher amperages?

[Drives]

Amanda:

I have followed your work over the years.  Nice, clean circuits, thank you very much.

This appears like a very good design, and I'm sure you will get it performing as well as your other circuits do.

For a PWM generator, I am still a fan of a 555 timer, but I see support for the tl494 on this board.

As for a FET driver circuit, I would recommend you look at IGBT manufacturers, and see what they use.  IGBT's can go to hundreds of amps, and are what we use in VFD's.  Your MSC controller probably uses some Mosfet's or IGBT's for the inverter section.  You could look at that if you need driver ideas.  Email me direct, and I could supply you with some example schematics.  The problem is all IGBT drivers I work with require dual supplies, so they will be good for ideas, but may not be the best solution for you.

I have been working on a couple of quick easy circuits myself to add to this board's DIY projects.  Time is my biggest hurdle....that and the fact that addmittedly, I'm not even good enough to be called a novice circuit builder. :-)

Keep up the good work, many of us look forward to your results.

[commanda]

Dean,

Thanks for the kind words. The pwm generator is only 2 op-amps; a sawtooth generator and a comparator. I have also IGBT's; when talking generally I tend to use the term "FET" to mean either. I also have books & plenty of reference material on designing smps's.

Amanda

[commanda]

Andjelo,

This board is only the controller. The output of this feeds the pwm generator, and that feeds the switchmode power converter (SMPS). The exact topography of the smps will vary by application. For instance, some people use a buck-boost converter to boost the low output of their generator in low winds to match their battery voltage. I will be using a buck converter to drop the high voltage output of my F&P (up to 380 volts) down to my 24 volt batteries.

Amanda

[mk32]

 nice set up

mk32 from the uk