[SOLVED] Wind Turbine Core design questions

[Nattyb52]

Hi all.

My name is Jim Wilson and I'm working on a wind turbine design that I'm hoping to prototype, test and develop.

I'm a complete newby to electronics design, but I have over 35 years of Civil Engineering Design experience.

I need to design and have someone build a set of 20 or so electric cores for the turbine prototype. As I said, I'm far from knowing what I really need to know, but hopefully some kind person here can help me find my way.

I need some guidance on what type and grade of material is best to use for the laminated steel core as well as who might best be able to construct the actual coils for me. Any help or guidance would be very appreciated as I'm only starting to dip my big toe into the power electronics pond and I don't want to get shocked. At this point, I don't even really know what questions to ask or what information will need to be provided but if anyone here can give me some useful feedback I'd really appreciate it.

Thanks

 

[Nattyb52]

Okay, after a little study, I'm looking for design information on DCPM generators.

 

[c_mitra]

Are you asking about the generator specifications? There are so many variables to start and you need to focus on a few to start.

Usually wind turbines are low RPM devices and the generator rotor should not have high speed. Because the centrifugal forces are less, you can have a bulky rotor. So, PM or wound core?

If the RPM is low, you can have large dia rotors. What is the power range you are planning to focus on?

 

[BradtheRad]

You can take a DCPM motor, drive it with a pulley, and it becomes a generator. It's not an ideal setup, for a motor is designed to be a load. Nevertheless it can give you an idea about how such a system performs in various situations. Relationships between speed, load, voltage and Ampere levels, etc.

 

[Nattyb52]

I apologize for the lack of clarity in my question.

What I'm trying to ask is if anyone can provide some guidance on what core material would be most appropriate in the coil design for a Permanent Magnet Direct Current Generator design for a wind turbine. I know there are a variety of options for an inductor core material including powdered cores, as well as different grades of Electrical steel cores. I'm just not familiar enough with inductor and core design to the point where I can tell a manufacturer what core material I would like to use for my turbine winding's.

 

[Easy peasy]

standard Si steel strip is what is usually used to make the magnetic cores in low rpm alternators/generators, i.e. electrical steel. 0.5mm is cheaper, 0.3 or 0.2mm has lower losses and would be used for higher frequencies. The field can be from rare earth high performance magnets - or from extra windings on the rotor with controllable DC current in this rotor assembly.
There is a lot to designing these generators for the most often encountered speed and torque that your machine will generate - slow speeds need a lot of poles ( pole pairs ) to make them efficient - and generally need to be larger for a given power ...

 

[Nattyb52]

standard Si steel strip is what is usually used to make the magnetic cores in low rpm alternators/generators, i.e. electrical steel. 0.5mm is cheaper, 0.3 or 0.2mm has lower losses and would be used for higher frequencies. The field can be from rare earth high performance magnets - or from extra windings on the rotor with controllable DC current in this rotor assembly.
There is a lot to designing these generators for the most often encountered speed and torque that your machine will generate - slow speeds need a lot of poles ( pole pairs ) to make them efficient - and generally need to be larger for a given power ...

It seems I will need to hire someone with the knowledge to help me develop the final product. At this point I'm only doing a small proof of concept prototype so just getting some positive numbers out of the machine, even without an optimized design, may be sufficient. Thank you all for your help, it's well appreciated.

 

[FvM]

I believe DC machine (with permanent magnet or wound stator) isn't the preferred solution because it involves a commutator and brushes. Since decades, DC power is preferably generated by synchronous AC machines with rectifier, e.g. in automotive alternator. Not sure if you need DC output at all.

 

[Nattyb52]

I believe DC machine (with permanent magnet or wound stator) isn't the preferred solution because it involves a commutator and brushes. Since decades, DC power is preferably generated by synchronous AC machines with rectifier, e.g. in automotive alternator. Not sure if you need DC output at all.

I'm actually working on a very different kind of generator/turbine system. It's been developed over the last 6+ years in my spare time.

I've done a ton of alternative energy research and patent searching and I believe I have a pretty unique design that will be quite a bit more efficient than a typical turbine design. At this point I can identify at least 3 different patent-able aspects of my design.

Because it's a permanent magnet system, it will be brushless and it will be direct drive with no need for any type of gearbox so far less complex and prone to breakdown.

Thank you all for the help and feedback, it's well appreciated.

 

[FvM]

Brushless means AC machine which definitely makes sense for a wind generator.

 

[Easy peasy]

Spinning magnets on the outside with wound stator in the middle - high diameter - is often used in these apps, aka F isher & Paykel early motor / alternator ...

 

[Carry for cents bazar]

I don't mean to offend you, but you are offending us. You need 20 years of electrical engineering and than you can build and prototype the turbine.

 

[Nattyb52]

I don't mean to offend you, but you are offending us. You need 20 years of electrical engineering and than you can build and prototype the turbine.

Well, you did offend me!

You are making a massive amount of assumptions about me as well as everyone else on this message board.

1. The name of this particular section of the boards is titled "Elementary Electronic Questions", not "I have a PhD and 20 years experience".

2. I don't believe you have the right to speak for everyone on this message board as to whether they are all offended or not.

3. You have no idea who I am, what my knowledge or background is, what my abilities or intelligence level is, what my plans for how to move forward are, what other people I have or will have involved in my project, nor any pertinent details related to my future plans or how much time and effort have already gone into this project.

4. I am sure as h*ll am not going to pause my project so I can acquire "20 years of electrical engineering experience", because I can very easily find experienced people who will join my project as it gets developed. Excuse me if I don't take your advice.

5. It's incredibly ignorant to make the broad generalization "...You need 20 years of electrical engineering and than you can build and prototype the turbine."

6. It's sure as H*ll not your place to be telling me what I do or don't need to proceed with my project.

Don't presume that you are the final authority on any of this.

I'm certainly not assuming anything, but I'm intelligent enough to know what I do and do not know as well as where and who to work with to make my project work. Why you feel the need to stick this dumb comment into a thread that has absolutely nothing to do with you, I really don't know, but I will be sure to ignore any future input that you may have.

Please don't bother replying, I'm not the least bit interested in your opinion.

 

[c_mitra]

All such designs are iterative process. Begin at the beginning and then continue till you reach the end. When you reach the end, then stop.

At this time, you have some general idea (at least in the back of your mind) about the generator. Generators and turbines are distinct beasts and you can safely consider them independently. You want a PM generator and the rotor is going to contain the PM designed for this purpose. The physical size will depend on the output power desired and the winding type on the stator will depend on the turbine RPM and the frequency.

In the initial phase, you need to focus on the electronics and the generator. Most of the commercial generators are highly efficient and improving the efficiencies is difficult because the headroom is small. If you are going to use a commercial generator, they are often available in a very wide range of option, the story ends here. Else, you can pick an established design and make modifications for your particular application. No point reinventing the wheel and it is indeed wise to start from the point others have left.

But in real life, it is the whole system that is important. You might have designed a road but designing a bridge is different. We know how to make a bridge, but sometime you need to make a tunnel because it is optimal. You need to consider the turbine, the generator, the superstructure and the overall performance. The performance is going to be the selling point and you need to revisit different parts again and again because some parts may not meet the expectations.

As the design evolves, the specifications too change. There is nothing wrong in that but it simply sends you back to the design stage.

 

[Kajunbee]

This link provides information on different wiring configurations for Fischer and Paykel motor that Easy Peasy mentioned.

TheBackShed.com - Rewiring the Smartdrive

How to rewire the Smartdrive to get different output voltages.

www.thebackshed.com

 

[c_mitra]

This link provides information

Unfortunately the link is not working; could you please check once more?

 

[Kajunbee]

TheBackShed.com - Rewiring the Smartdrive

How to rewire the Smartdrive to get different output voltages.

www.thebackshed.com

--- Updated Aug 8, 2020 ---

Let me know if it is working now. It is working on my end. Not sure if it matters but I copy/pasted it.

--- Updated Aug 8, 2020 ---

Easy also mentions the early motor. This video gives info on how the older motors differ from newer models.

 

[c_mitra]

I am not sure what the power output you are looking at. It is good to have as high a voltage as possible with the design parameters (insulation and arcing being the most important) and lower current (to minimize copper losses). After all, your output is AC and you can adapt the voltage easily.

The generators are optimized at a certain RPM (within a fixed range of RPM). If you are looking at a 1 MW generator, you may have a voltage of 6.6 or 11 kV (AC) and 1-2 kA current. Modern generators will have still higher voltage output. If you are having a 1-5 kW generator, you may like to have a voltage output of 220V-440 VAC and 5-20A current rating. Changing the turns in the coils can get you a different voltage but at the cost of efficiency. You need to design the generator from the beginning for the chosen voltage.

Best solution in my personal opinion is to rectify the output and use a efficient DCDC converter to get your choice voltage output.

--- Updated Aug 8, 2020 ---

Regarding the video posted:

You run a generator with an electric drill, say perhaps 300-500 W and the use the output to run a CFL, perhaps 10-20 W. What a demonstration!

I can read datasheets but the speaker never talked about data sheets.

The permanent magnets are very interesting but they are expensive. Rare earths are all produced in China and they control the price. Today they are cheap but you cannot tell about tomorrow. Same thing happens about cobalt, mostly extracted from ores in Congo and the supply is again unreliable. For generator, it may be better to have the stator outside (rotor may be in the center). There are too many details and designing a motor is straightforward but complex! Generators and motors are different beasts and you need to design from the ground up.

 

[Kajunbee]

Don’t forget spinning the tub also, but I get your point. But how do you know one turbine design is better than another. This would have to be done at a test facility for verification. So if OP is just concerned with turbine design does he need a generator at all? Also the generator efficiency can be worked out without connecting it to the turbine. It’s efficiency doesn’t change whether it’s connected to a turbine or not, or does it.

 

[c_mitra]

By turbine I understand the structure with blades; for wind turbines, the blades are long and slender but for water turbines they are small and heavy. The design for high temp gas turbines are complicated but they still have a very large number of vanes (half of them are stationary). A well designed generator can have high efficiency at the design RPM; but I am not so sure about the wind and water turbines. Gas turbines, I am told, approach very high efficiencies (about or above 50% of the Carnot efficiency), that just means that lots of energy is released with the exhaust gases.

I thought the OP wanted the electrical core design (the stator; that contains the coils) and I did not get the impression that he wants to design the turbine blades. I am still not sure the power level he is interested because the design strongly depends on the power level begins considered.