http://www.usna.edu/EE/ee320/Supplements/dcdc5_driver.pdf



Hi, the circuit is from the .PDF file. Searching for circuit to create Vdr, maybe a charge pump can be used.
Comments welcome.

 

Maybe this will help; http://www.maxim-ic.com/app-notes/index.mvp/id/2031

http://www.ti.com/lit/an/slua185/slua185.pdf

http://www.national.com/en/power/index.html

http://www.national.com/en/power/index.html

I know I keep saying the same thing over and over, but really am trying to help you.

First your basing your thinking on a 'SOLAR' controller. Which is a completely different situation than a 'WIND' controller. With the 'solar', a panel will self limit to a peak output. Once it reaches that peak it will put out no higher voltage.

With a 'wind' gen or PMA, the voltage is varying with the speed. Higher speed - higher voltage, lower speed - lower voltage. A buck-boost or fly-back regulator is better suited. They will increase when wind is slow and decrease when it is fast, in all giving more usable output. Check out this link; http://www.wholesalesolar.com/Windy/MPPT-article.html

A regulator IC has all of your basic circuits built in, the PWM, comparator, and output for the mosfet driver. And don't forget, as long as the voltage is higher than the battery, its amperage that does the charging.

 

Hi, thank you for the options, the PMA creates a very high voltage at a very low RPM, I do not think a boost would be useful.

While I am waiting for the high side gate drivers to arrive, is it possible to use a 2n3055 npn power transistor to construct the buck converter?
2n3055
Max hfe = 70
Min hfe = 20
VCBO = 100 v
VCEO = 60 v
Ic = 15 amps
Fr = 2.5 Mhz
Po = 115 watts

What would be required to turn it on and off using a nand gate?
Would it be possible to use the nand gate to turn on and off a smaller transistor that could control the larger transistor, like a Darlington pair configurations? Turn on the larger transistor to full saturation so it would pass as much current to battery that the PMA can supply? Have the nand gate controlled by a oscillator?
I am not sure of the calculations but it looks like 0.22 amps driving the base of the large transistor would create full saturation.
Comments welcome.

 

Hi, the IR2117 have arrived and I completed all the high current connections of the buck converter. Using a Zener diode as Vcc to power just the nand gate oscillator I was able to illuminate a LED with a quarter turn of the PMA. Not great results but it is a start. I have to test the IR2117 with the oscilloscope to determine if HO is oscillating. I wired the test circuit and used a 12 volt halogen light as a test load and spun the PMA manually. The PMA was very easy to spin until the MOSFET turn on, then I was unable to spin the PMA. I believe the MOSFET is not turning off. My concerns are there is a lot energy stored in the input capacitor and I do not want to harm my oscilloscope. Are there any points I should avoid when testing the circuit????? The chassis ground and each channel ground are a the same common point, is there a safe method to use when testing the circuit with the scope? Comments welcome.

 

May I ask a few questions about your PMA? Did you buy the PMA or build your own? If you built it where did you get the rotor magnets and what do they look like? Do you have any photos of your rotor you could post?

I'm asking because I'm gathering information to make an alternator based brushless motor. Thanks for any information you can give.

 

Hi, http://www.magnet4less.com/ is where I purchased the magnets. I made the PMA. The top and bottom rotors are metal backed. No metal in the middle rotors. For a PMA design the traditional wisdom suggests the internal resistance of the stators should be as low as possible. I used a stratum stator approach so I could try many different coil configurations. If you need any more info I will be happy to help if I can.

 

THANK YOU! Didn't realize you were using an axial flux alternator. Do you have laminations in your stator coils? Thought you might be using a converted car alternator.

As far as your mosfet not turning off, if your frequency/duty cycle from the oscillator is too high, the circuit will see it as always on. Thats why PWM can run a motor smoothly.

 

THANK YOU! Didn't realize you were using an axial flux alternator. Do you have laminations in your stator coils? Thought you might be using a converted car alternator.

Hi, I do not understand, what are laminations in the stator coils? I made each stator with inputs and output connections.

 

Laminations are like the steel part of a transformer. To gather the magnetic field and make the gen more efficient.

Again just my opinion on this, with all the stages in your PMA it is going to be hard to turn when producing electricity. Have you thought about making the control able to cut out the number of stages used when the wind is slow?

Use a comparator circuit to switch on the next set of coils when the first set reaches a certain voltage. This would allow the blades to move when the wind is low and as it increases another stage cuts in and then the next. It would allow your PMA to be more effective.

You really need to do some testing to quantify the out put and force need for that out put. To try and design something that will work, without knowing all of the parameters is just shooting in the dark. Again just my take on doing things.

 

Hi, photo shows input timing signal from 555 timer and output (HO) of IR2117. The MOSFET is not connected. I had to connect Vs to ground. Duty cycle is a little greater then 50%.

The application notes says that the logic ground and power ground should not be connected but their diagram shows they are connected, I find this very confusing. I am not sure where to generate Vcc? Comments welcome.

 

Hi, project update. I found a application note from Fairchild that I am trying to use as a guide line.

Fig, 14 , pg 6
http://www.fairchildsemi.com/an/AN/AN-6076.pdf

I have to read the paper a few times, it is starting to make more sense.


When I add the MOSFET the IR2117 will turn on but not off. I am currently working to solve this problem. Comments are welcome and thank you for the help I have been receiving.

 

Since your Vs pin on the IR2117 has nothing on it as a load connected to ground (as shown in the data sheet), once the mosfet turns on it is "latched". By that it means that the voltage from the battery is feeding back to the gate and keeping it turned on.

You do know that the diode and inductor are serving no purpose in the circuit,right?

 

Hi, when I started the project I had no knowledge of any kind regarding a buck converter. I have been doing a lot of reading. So far I have been testing using a 12 volt light as the test load and I will advance to try to charging a battery after I am successful turning the light on and off. From some of the reference material it looks like the IR2117 is used for resistive loads and the IR2125 is for charging batteries.

As I understand it the inductor and diode complete the output circuit so the energy stored in the inductor is transferred to the load when the MOSFET is off.

The VDR capacitor of the IR2117 should be 10x larger then the boot strap capacitor.
The boot strap diode should be a fast recovery diode.
Vcc should be 10 volts and VDR should be 15 volts.

I found a similar project at http://forum.allaboutcircuits.com/attachment.php?attachmentid=37862&d=1324052949
that was successful that added 5 ohms resistors to the gate and boot strap.
I am going try to reproduce their efforts after I check my connection again and replace the MOSFET. I will post results when available. Thank you for the help I have been receiving and comments are welcome.

 

Would you please try to put into words what you want this circuit to do? You have built a very powerful PMA, and are very vague on the out-put specs.

You NEED to know what the open circuit voltages are of the PMA at different RPM's. Without this information how are you going to make a circuit that works? Think about it, without this information how can anything be designed?

Your PMA is not going to be suitable for a single battery, you do know that right? A fairly big bank of batteries is going to be needed to accept the amount of power you can make. How are you going to deal with the power once the batteries are charged and the wind is still blowing? These are questions that also need to be dealt with.

Not trying to discourage you, just trying to point out things you need, to make this work.

 

Hi, I plan on using a discrete dump load controller that will monitor the battery bank and will divert the charge current to a dump load after the battery bank reaches full charge.

The PMA has inputs and outputs on the stators and can be configured many different ways. Max Vin of test circuit will be 50 volts DC open circuit. Max Iout is 4 amps. I will be using a hand crank to manually spin the PMA during testing of the circuit.

I am interested in finding out how the circuit will affect the torque required to spin the PMA under load and how fast the circuit will discharge the input capacitor.

Once the buck converter is working I can parallel the MOSFET’s.

Your input is greatly appreciated, thank you.

 

Hi, The photo displays the Vs wave form on top and the IR2117 trigger input on the bottom. I am using switching diodes because I do not have any fast recovery diodes.

The only way I could get the MosFet to turn off is to connect Vs from the IR2117 to ground. Control signal is 10 kHz and I am using bench power supplies and a 12 volt light for a load.

I am making progress.

 

The only way I could get the MosFet to turn off is to connect Vs from the IR2117 to ground. Control signal is 10 kHz and I am using bench power supplies and a 12 volt light for a load.

This is the way mosfets and drivers work.
Your using a high side switch in the circuit, you would be farther ahead to use a "Half-bridge driver" and two mosfets. This will do two things for you- 1. it will shut off the high side mosfet,
2. it will allow your 'boot strap cap' to recharge(with out needing a "charge pump".

You also need a Diode in between the mosfet source and the inductor/battery. This again will do things that are needed.
1. it will allow the gate to be isolated from the battery letting the mosfet turn off.
2. it will stop the battery voltage from feeding back through the "intrinsic" diode that is part of all mosfets. Without this extra diode the battery will discharge through the stator coils of the PMA when the wind isn't blowing. This diode has to be big enough to handle all of the current the PMA will put out. The wire to the mosfet driver, Vs terminal will be before this diode, that way the battery voltage won't affect the gate when the mosfet turns off.

 

You may not like this, but you do know what they show on Youtube is not always true, right? The video you linked to in the beginning of this is one of them. What he was saying about the circuit is not possible. It goes against the laws of physics, kind of a reverse "free energy".

Before you get too upset/mad, stop and think about it with an open mind. When electric is generated it takes energy to do. It doesn't matter how fast you switch it on and off (what you and he are doing) it takes the same amount of power for each on time.

You have a multi-stage PMA, the only way to lessen the amount of power/force it takes to generate the electric is to use fewer of those stages in your PMA. As the wind picks-up in force it will increase the voltage, this would be sensed through a comparator and turn on another stage of the PMA.

Really take some time and think about this. Then in a second part of the circuit you would use a buck or other converter to charge the batteries. This type of a circuit doesn't break any laws of physics and can be made to work.

 

http://www.vawts.net/t45173979/mppt-specs/?page=26&sort=newestFirst

http://www.fieldlines.com/index.php/topic,146421.0.html

http://www.anotherpower.com/board/index.php/topic,269.0.html

Hi, MPPT is just starting to be applied to micro wind turbines. It takes a high voltage and low current and steps it down to a smaller voltage with high current. If the micro controller is removed from the circuit a Buck Converter is left. I have no experience with power electronics and I am trying to start with just the basic buck converter and than add the micro controller at a later time.

I am noticing there is a lot of RF interference in my circuit. Some of the wires are inducing signals into other parts of the circuit. This is a learning experience for me.

At this time I do not believe that it is a spoof. Other people have been successful using the technique and some companies are starting to offer the controllers. I do understand what you are telling me and your idea does have merit but without solving the internal resistance problem of the stators most of the power produced by the PMA will be lost as heat.

I posted some links where the topic is being cover. The people with working systems will be able to communicate how the their systems work much better than I can. I just trying to get a buck converter working.

Thanks for taking the time to respond, I am getting closer to a working project.
I maybe using the wrong gate driver. I did find a application note that shows a IR2125 being used for a 12 volt battery charger, fig. 26, page 17

http://web.mit.edu/6.131/www/datasheets/float_drive.pdf

Comments are always welcome, thank again

 

I didn't read every thread of the first link, but did read the second and third, and not one of them is going at it like you are . And none have what is shown in the video link. But in the first link the guy is using a DC-Dc chip to do the buck converter like I said . They also set their gens up to log the outputs for a while so they had real numbers to work with, like I said .

I guess I'm just a dinosaur with this stuff, cant see the need for a micro-controller(uC). The uC is slower than a comparator in measurement and not as easy to vary in the PWM mode as a DC-DC chip. Plus a uC is more sensitive to out side electrical signals (lightning and static) than a set of chips. And after you get a circuit built, theres no need to keep logging the data.

Are you also asking questions on the other sites?

quote "At this time I do not believe that it is a spoof. Other people have been successful using the technique and some companies are starting to offer the controllers. I do understand what you are telling me and your idea does have merit but without solving the internal resistance problem of the stators most of the power produced by the PMA will be lost as heat" --- Why would there be any heat? With the stator connection 'shut off' and not being rectified it isn't making any power (open circuit) so little if any heat. This really looks to be what the video link is doing.