Kragten 2-bladed 1.8W windmill with no iron in the coils

Here is another design document available free from Adriann Kragten.  He wrote to me:

Recently I have written report KD 664 which can be copied for free from my website: at the menu KD-reports. The title of this report is: “Calculations executed for the 2-bladed rotor of the VIRYA-1.8W windmill (lambda design = 6.25, wooden blades) used in combination with an 8-pole permanent magnet generator frame size 71 with a stator with no iron in the coils”. This is a rather simple rotor with water proof plywood blades coupled to each other by a thin stainless steel strip to make the rotor elastic. The blades have a constant cord and blade angle. I have used the Gö 711-12% airfoil which has a lower side which is flat for 97.5 % of the cord.

“The rotor is meant to be used with the radial flux PM-generator as described in public report KD 644. As this generator has almost no sticking torque, it can be used in combination with a rotor with a low starting torque coefficient and still have a low starting wind speed. As there are no iron losses, the generator will have a high peak efficiency . The advantage of using a standard motor housing is that the coils and the magnets are well protected against rain and that most components are mass produced and therefore rather cheap.

“This new report KD 664 contains detailed drawings of the rotor and the hub in the appendix. The VIRYA-1.8W makes use of the same head and tower as used for the VIRYA-1.8. Fotos of drawings of these head and tower are given in the manual part 2 of the VIRYA-1.81 which is given at the bottom of the menu KD-reports. To give an impression of the VIRYA-1.8 rotor drawings, I have added drawing 1801-01 as an attachment.

“Yours sincerely

“Adriaan Kragten”

About hugh

I live off-grid in NW Scotland and have spent my life playing with wind turbines. I also love small hydros. Hands on renewable energy is my thing and I like to learn and to share my experiences.
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3 Responses to Kragten 2-bladed 1.8W windmill with no iron in the coils

  1. Karana Olivier says:

    Hi Adriaan

    I have been developing micro windmills that produce high voltage in strong winds (60 volts for 24 pole, 12 coil system and 40 volts for the 16 pole, 8 coils systems – both in single phase. These are my first attempts at making such small units and my main reason is to design something cost appropriate for local entrepreneurs who charge cell phones in rural villages here in Ivory Coast. Wish I had the beautiful technical drawings you have done. But I am happy to share pictures.

    I am told that my meters are not getting an accurate read on the resistance so I am still having difficulty measuring the resistance to get a more accurate read on the wattage.

    The frames are made of wood because of the theme of accessibility. Have you tried to design and build your own voltage charge controllers to charge a battery? I have a few designs that not sure about their performance. And looking for other options that I can build locally. I am not an electrician and my builds are rather amateurish but I want at least to finish and handover to someone more skilled in this sector. Any advice would be helpful.



  2. hugh says:

    Adriaan writes: “Using the same idea as used for the 12-pole PM-generator as described in report KD 667, I have designed a bigger 24-pole PM-generator in report KD 668. This report can be copied for free from my website: at the menu KD-reports. The tittle of KD 668 is: “Ideas about a 24-pole permanent magnet generator with a stator with no iron in the coils for the alternative VIRYA-4.2 rotor for battery charging or for combination to the 1.1 kW, 3-phase asynchronous motor of a centrifugal pump”. So this generator can be used in two different ways depending on the winding which is laid. The generator is rather light for its armature volume as it has a hollow armature and aluminium bearing covers. It might be possible to use the generator as a direct drive synchronous motor for a small car or boat. This use is explained in chapter 7 of KD 668. To give an impression of this generator, I have added figure 2 out of KD 668 as attachment.”figure 2 of KD 668

  3. hugh says:

    Adriaan writes: “Recently I have written the new report KD 667 about a radial flux PM-generator with no iron in the coils. The titel of this report is: “Ideas about a 12-pole permanent magnet generator using a motor housing frame size 100 and a stator with no iron in the coils for use in combination with the VIRYA-3B3 rotor”. This report can be copied for free from my website: at the menu KD-reports. To give you an impression, I have added the assembly drawing of the generator, which is given in figure 2 of KD 667, as attachment.”

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