DC-DC Converter for a wind turbine
By mukunthko, Section Controls Posted on Wed Feb 28, 2007 at 11:21:51 AM MST
DC-DC Converter for a wind turbine

Hey guys I built a wind turbine at home. I'm now planning to connect a dc generator (ametek),derived from a permanent magnet treadmill motor to it. In order to regulate the voltage to charge a battery, I was looking at dc-dc converters when i found this 10-56VDC to 12VDC converter. http://www.boatersland.com/dcdcconviso.html I was wondering if anyone on the board has used this. They've mentioned an input range on 10v-56V but my generator would be producing voltages in the range of 0-50V. So would i need to build a circuit that cuts in at 10V or do you think it would be inbuilt in this converter. I was also wondering if the spikes from the generator would cause any damage to this converter. Would i need to use any protection or filters in between to prevent that? I've also been thinking of using solar charge controller like this one http://www.windmillshop.co.uk/ProductInfo.asp?ID=16 Will there be any issues with using any of this solar stuff for wind applications (I'm particularly concerned about the spikes) Please advise guys.

DC-DC Converter for a wind turbine | 11 comments (11 topical)

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#1) by mukunthko on Wed Feb 28, 2007 at 04:23:54 AM MST

Sorry. Should've mentioned this is in the post but the solar charge controller will recieve its input from the dc-dc converter and feed it to the battery(just to prevent overcharging) but the spikes should hopefully not carry over???

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#2) by drdongle on Wed Feb 28, 2007 at 05:13:41 AM MST

11.5 V ( acording to the specs) will be the cut in voltage of the converter, nothing extra needed. As far as spikes are concerned the max specified input is 56 volts so you don't want to exceed this. A shunt regulator can limit the input to a safe level.  The Juta regulator is for a 12 or 24 volt system. You need one that will kick in at about 48 volts. Carpe Vigor, Dr.D

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#3) by AbyssUnderground on Wed Feb 28, 2007 at 10:33:04 AM MST

Just something you should note, dont use a solar regulator on a wind generator! http://www.repowered.co.uk - My Renewable Energy site. msn[at]m3ezw.co.uk - my msn if you want a chat.

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#4) by wooferhound on Wed Feb 28, 2007 at 01:14:56 PM MST

A big capacitor will absorb the spikes make sure it can handle the max voltage of the spikes W o o f -={(

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#5) by cardamon on Wed Feb 28, 2007 at 08:10:01 PM MST

I have been considering using a dc-dc converter to interface my turbine to my batteries, so I wil share my thoughts and what I have learned about this method so far.  The main problem I see the lack of a way to coordinate your output current with the available current.  If the converter has a fixed output, the batteries may "want" the same amount of power from it regardless of what the turbine has available.  This could make the turbine see the converter as a short and/or not start.  Now it may work depending on how the converter reacts when it cant get the input amperage it wants - if it automaticlly folds back the output then it might work, but if not than it may shut down or stall the turbine.  I think your best bet would be to get one of the dc-dc converters made by solar controllers, they have a line that are not only bi-directional, but multiply (or divide) the voltage by 4, i.e. not a fixed output.  This will allow the converter's output voltage to vary with the turbine voltage, thus pushing more current to the batteries as the turbine speeds up and has more available.  Plus because the unit is bi-directional, maybe your turbine can lock to the battery voltage through the converter thus preventing/reducing the chance for overvoltage conditions.   I dont have any hands on experience with any of this, just some stuff that I have been throwing around with some other people.  I would like to hear if others have used a dc-dc converter and how it worked and also what others think of my above theory of their operation for this application. Regards, Cardamon

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#6) by Tom in NH on Thu Mar 01, 2007 at 06:33:49 PM MST

I just started experimenting with a homemade dc-dc buck converter. I have it set to convert alternator voltage down to 15 volts. It's only just cobbled together on a breadboard at this point, but the way it behaves is as follows (and I think you could expect the converter shown in the link to behave roughly in the same way). When there is no wind, it consumes 5ma from the batteries. When wind is below cut-in and alternator is below battery voltage it consumes 0 ma. When wind is above cut-in, alternator is above battery voltage, and below 15v, electricity feeds straight through the converter and into the batteries. When alternator is above 15 volts, the converter reduces it to 15 volts. --tom [ Parent ]

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#7) by cardamon on Thu Mar 01, 2007 at 08:18:40 PM MST

Tom, Interesting.  What is your nominal turbine voltage?  Also what happens to your charge rate as the turbine accelerates beyond the 15 v point? [ Parent ]

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#8) by Tom in NH on Thu Mar 01, 2007 at 10:27:33 PM MST

My turbine voltage is from 0-50v depending on wind. Exactly how it will affect charge rate remains to be seen, however it will increase the current going into the batteries. Testing with my bench power supply using light loads, the converter showed an output current 80% greater than the input current when the input voltage was 20 volts. How it will behave in the real world remains to be seen, but it looks like these things could be a good idea for wind turbines. I expect I'll know more in 24 hours as it looks like a wicked blow is about to barrel down on the northeast. --tom [ Parent ]

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#9) by mukunthko on Fri Mar 02, 2007 at 03:11:15 AM MST

This off the shelf DC-DC converter shuts down when the voltage falls below 10 V as well. SO do you have any suggestions to prevent this? Maybe divert it to a power resistor until the turbine reaches the threshold? Also would you mind sharing you home made buck converter design with us please? [ Parent ]

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#10) by Tom in NH on Fri Mar 02, 2007 at 05:37:31 PM MST

It isn't really my design, but one provided by Switchers Made Simple 6.24 software from National Semiconductor. It's a free download. I used their LM2678 buck converter chip. I'm sorry to say I'm back to the drawing board. The wind we had today was so strong I was pushing 50 volts and the LM2678 has an absolute maximum input rating of 40 volts. Woe is me. --tom [ Parent ]

Re: DC-DC Converter for a wind turbine (3.00 / 0) (#11) by Ungrounded Lightning Rod on Fri Mar 02, 2007 at 07:15:25 PM MST

The trick will be to get it to adjust the amount of current it pulls from the mill to keep it running near max power point for a given wind. A true max power point controller may track the sweet spot by slowly cycling the current up and down a bit and seeing what happens to the voltage.  But you should be able to come up with a fixed input voltage supplied -> current demanded curve to get a very close approximation to that result. [ Parent ]

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· magnet · http://www .boatersland.com/dcdcconviso.html · http://www .windmillshop.co.uk/ProductInfo.asp?ID=16 · Also by mukunthko