I thank you very much for your replies; They are helpful and you guys nailed right in the bottom line of the whole issue and current project.

I'm trying to build an efficient e-bike and an small 2 passengers car, but the only DC motors I have available in this town are regular car starter motors, from all brands.

I've tested some of them and they all have very low efficiency and in some cases poor quality. There are starter motors that have reduction gears made of plastic; they are kind of disposable items and not good as the main traction motors for an electric vehicle.

Also I tried "an oriental" hub motor for a bike, and no offense, they are not very good. Low cost though, but it's not what I'm looking for.

Thus I started to build this Halbach design DC motor, with the purpose to make a reliable, efficient, strong and good quality motor, but now you know, it's very complicated to make it right.

You're talking about these 96% efficiency DC motors already available; Please advice about the brand or the specific features they have that are that good. I'd like to do some evaluation in an electric vehicle and see it's performance.

I've also found this supplier for DCBL motor controllers:

http://kellycontroller.com/index.php

And I also thank you for your advice about Endless-sphere forums. That's exactly the people that are trying to solve the same problems I have with DCBL motors in electric vehicles.

I'll keep you posted. Kind regards.

 

I thank you very much for your replies; They are helpful and you guys nailed right in the bottom line of the whole issue and current project.

I'm trying to build an efficient e-bike and an small 2 passengers car, but the only DC motors I have available in this town are regular car starter motors, from all brands.

I've tested some of them and they all have very low efficiency and in some cases poor quality. There are starter motors that have reduction gears made of plastic; they are kind of disposable items and not good as the main traction motors for an electric vehicle.

Also I tried "an oriental" hub motor for a bike, and no offense, they are not very good. Low cost though, but it's not what I'm looking for.

Thus I started to build this Halbach design DC motor, with the purpose to make a reliable, efficient, strong and good quality motor, but now you know, it's very complicated to make it right.

You're talking about these 96% efficiency DC motors already available; Please advice about the brand or the specific features they have that are that good. I'd like to do some evaluation in an electric vehicle and see it's performance.

I've also found this supplier for DCBL motor controllers:

http://kellycontroller.com/index.php

And I also thank you for your advice about Endless-sphere forums. That's exactly the people that are trying to solve the same problems I have with DCBL motors in electric vehicles.

I'll keep you posted. Kind regards.

kelly controllers are not well made. see here; this is the controller you would likely buy if you bought a brushless controller from kelly.

The brushless controller & motor design for large traction applications is in its infant stage. there is not much available. the 96% figure I quoted, I cannot remember where I found it. here are some of the more commercially available large brushless motors (90-92% efficient). here is a 95% efficient 100kw BLDC, albeit not very commercially available. The problem is that building controllers gets exponentially more difficult as the motors get larger and motor technology can't advance until controller technology advances. Also affecting the controller and motor technology advancement, is battery technology. The big guys aren't going to go off spending a bunch of R & D money to come up with bigger & better motors & controllers until its financially responsible to do so, and right now batteries are holding EVs back. Battery tech is evolving fast though; just a few more years and I think the EV scene will see a lot of growth.

What a lot of guys are doing, is using large brushless hobby airplane motors (turnigy, et.al, I believe they are in the high 90's effeciency %); sometimes more than one on the same bike. They use hobby airplane ESCs, take them apart, beef up the mosfets & caps, and go. works well for bike, but I can't see it being a good thing for cars.

I decided to build a brushless gocart a while back. I had picked out one of those 90-92% efficient models I linked to. Before making my purchase, I started looking around about making a controller for it and found that it is a really daunting task. you can see me get slapped with a big dose of reality right here. I spent a couple of months reading all about high power switching and batteries and motors and mosfets and a myriad of other crap. I ordered parts and got about half way through my brushed motor project and ran out of money. sometime next year I will pick it up and finish; then try building a brushless controller. It's really not that simple.

 

It's really not that simple.

You bet.

Please see this beautiful Halbach motor from LaunchPoint:

http://www.youtube.com/user/geoffreyalong#p/a/u/0/Sjm5Y3BHpc8

Nice engine.

 

You bet.

Please see this beautiful Halbach motor from LaunchPoint:

http://www.youtube.com/user/geoffreyalong#p/a/u/0/Sjm5Y3BHpc8

Nice engine.

yes I ran across the launchpint website while I was googling halbach motors. In the video, the guy is using an airplane ESC to run it. This is an option, but the thing is that usually the airplan ESCs use back EMF zero crossing for commutation. Back EMF zero crossing only works above a speed. this works well for airplanes, because they have almost no load when starting up, so the ESC just uses a preset ramp up, until it starts receiving back EMF data, and then full control is possible. This doesn't work well in a traction application because you need full use of the motor at low RPM, all the way to zero. So, you really need to have hall sensors to control the commutation. Some of the guys I mentioned using airplane ESCs and motors get away with it, but I'm not sure how; you could ask them. I think most though use hall sensors

 

This is just my ramblings and I do ramble. If I was going to make my own BLDC motor from scratch like Mel, it would be an "in-runner". There are two different types of BLDC motors- 'in-runner' and 'out-runner'.

An out-runner is like Mel is making. The rotor is outside of the stator coils. It makes the rotor larger and makes the dynamic balance, because of it size, more critical. It has to have more poles, because of its larger diameter. While that may give more torque and power, it complicates things more in the electrical drive of the motor.

An in-runner has the rotor on the inside of its stator. The smaller diameter, though it can still be made larger than say a RC plane motor, is less critical on balance. It can have a smaller number of poles, because of the smaller diameter. By making the motor wider instead of larger in diameter, you can get the same amount of torque and power. Along with making the electronics less complicated.

your mileage may vary.

 

An in-runner has the rotor on the inside of its stator. The smaller diameter, though it can still be made larger than say a RC plane motor, is less critical on balance. It can have a smaller number of poles, because of the smaller diameter. By making the motor wider instead of larger in diameter, you can get the same amount of torque and power. Along with making the electronics less complicated.

your mileage may vary.

The reason RC Planes are outrunners is they cannot fit powerful enough magnets on the rotor, though some are inrunners, the more powerful ones are the outrunners.

For a larger sized motor, it is size and power of magnets to get them aligned so the field is unidirectional (Halbach orientation)

 

@Mel- while this isn't a Halbach array motor, it might interest you for your application. Its fairly small, but the site gives the needed information to figure out the winding and such to scale it up. Maybe use a car brake drum fro the rotor. That would make it around 10-11 inches diameter by 2 -2 1/2 inches wide.

This motor is slow and has a lot of torque. Just what a bike or vehicle needs.

 

@Mel- while this isn't a Halbach array motor, it might interest you for your application. Its fairly small, but the site gives the needed information to figure out the winding and such to scale it up. Maybe use a car brake drum fro the rotor. That would make it around 10-11 inches diameter by 2 -2 1/2 inches wide.

This motor is slow and has a lot of torque. Just what a bike or vehicle needs.

was there supposed to be a link in there?

 

Yeah, don't know why it didn't show in the actual post? Try again; http://www.aerodesign.de/peter/2001/LRK350/index_eng.html

 

Yeah, don't know why it didn't show in the actual post? Try again; http://www.aerodesign.de/peter/2001/LRK350/index_eng.html

I don't have time to read all that now, but it looks like an excellent reference. bookmarked!
Thanks

 

Heres a blog also that a guy is building a different version of that motor. http://myownhybrid.wordpress.com/

And a PHD thesis on the same subject. http://www.elkraft.ntnu.no/eno/Papers2011/Krovel-Phd-thesis.pdf

 

Can I assume this motor has captured your interests as well shortbus?
I really haven't had much time to research, but this topic has gotten my interests focused more on how the motors (namely BLDC and also this halbach) actually work, and all the science of it, whereas before I was only interested in how the controllers work.

 

kelly controllers are not well made. see here; this is the controller you would likely buy if you bought a brushless controller from kelly.

I thank you for your advice. I really like the 120V controller. I guess it can move my prototype and also a bigger motor.

My next prototype will have two magnet disk as a rotor, and the coils in between. It may have more torque.

Dozens of ideas come to my mind with your feedback.

 

@Mel- while this isn't a Halbach array motor, it might interest you for your application. Its fairly small, but the site gives the needed information to figure out the winding and such to scale it up. Maybe use a car brake drum fro the rotor. That would make it around 10-11 inches diameter by 2 -2 1/2 inches wide.

This motor is slow and has a lot of torque. Just what a bike or vehicle needs.

Thanks for the info shortbus. I'm very well acquainted with those motors. Actually my prototype has some similarities with them.

Kind regards.

 

Heres a blog also that a guy is building a different version of that motor. http://myownhybrid.wordpress.com/

And a PHD thesis on the same subject. http://www.elkraft.ntnu.no/eno/Papers2011/Krovel-Phd-thesis.pdf

It's very interesting what this guy is doing with his hibrid vehicle.

One of the big advantages of the Halbach Magnets Array is that you may build the motors in different ways, according with your particular application.

The smallest Halbach motor I've seen is 1/2" OD. You may build it as big as you want.

Again, mileage may vary.

 

Prototype Motor Update:

This week I'm working in building an small furnace for melting aluminum and cast some parts that I need.

At this point, I'm going to cast and turn a 2 1/2" coupling for fixing the rotor into a wheel balancing machine, before I go any further with the project.

Once I have the rotor well balanced I can continue making some other parts for assembling.

 

@ Strantor- At the moment just really looking at all possibilities. My main idea is to rewind a three-phase motor as a two-phase at lower voltage. Found some books that explain the formulas and how to rewind motors at home. And some old books from the early days of motors, 1890's to 1920's that have voltages, frequencies and phases that worked at the time. Before things were standardized. With the electronics of today they can still be viable. Maybe?

Wish I could afford a book on Bldc design and theory I found. $175 a copy, to much for this old dummy.

Just from the way I understand things, a lot of what people are calling "Halbach array magnets" doesn't really make them that. Most of them are using off the shelf magnets and not paying attention to the polarity. Just because you have magnets in a certain shape doesn't make it a Halbach array. I doubt if people are paying to have the magnets polarized the correct way to build a Halbach array, and most of these motors will work with just standard magnets. Just not as well.

@ Mel - the motor with the magnet on the flat side of the rotor is called an 'axial flux' motor. If you start looking for these type motors there are a lot of college thesis papers written on them. Some of the papers are just theory but the good ones are reports of people that made working models of what the paper is saying. Those are the ones to concentrate on.

 

Just from the way I understand things, a lot of what people are calling "Halbach array magnets" doesn't really make them that. Most of them are using off the shelf magnets and not paying attention to the polarity. Just because you have magnets in a certain shape doesn't make it a Halbach array. I doubt if people are paying to have the magnets polarized the correct way to build a Halbach array, and most of these motors will work with just standard magnets. Just not as well.

@ Mel - the motor with the magnet on the flat side of the rotor is called an 'axial flux' motor. If you start looking for these type motors there are a lot of college thesis papers written on them. Some of the papers are just theory but the good ones are reports of people that made working models of what the paper is saying. Those are the ones to concentrate on.

What I know of the Halbach Array is that polarity is the important issue; not the shape or size of the magnets. The polarity in my prototype is like this:

> v < ^ > v < ^ > v < ^

Where I have 12 magnets making 4 poles; they are supposed to be followed by the 3 energyzed coils to rotate.

I'm familiar with the axial and lineal flux motors, both out-runners and in-runners.

I just hope my prototype works after connecting the controller.

For now I have some modeling, casting and turning to do.

Thanks again for the heads up.

 

Where I have 12 magnets making 4 poles; they are supposed to be followed by the 3 energyzed coils to rotate.

this is the part I still don't understand; 4 magnet poles, 3 electromagnetic coils. I seem to remember running across a similar configuration before with more poles in the stator than on the rotor, but I can't find it now.

And the winding configuration; most (well, all motors that I have seen) have coils in series 180 mechanical degrees apart. this causes the mechanical load caused by the electromagnetic attraction to be evenly distributed. The way I see your motor; if it even rotated in a circle, the load be be 100% applied to only one side of the rotor, causing undue stress to it. maybe I'm wrong; are you able to explain it if it is your own idea? or post link to where you got the idea?

 

What I know of the Halbach Array is that polarity is the important issue; not the shape or size of the magnets. The polarity in my prototype is like this:

> v < ^ > v < ^ > v < ^

Where I have 12 magnets making 4 poles; they are supposed to be followed by the 3 energyzed coils to rotate.

I'm familiar with the axial and lineal flux motors, both out-runners and in-runners.

I just hope my prototype works after connecting the controller.

For now I have some modeling, casting and turning to do.

Thanks again for the heads up.

Mel, from what I've read the magnets must be the equal size and shape, both in the segment size and shape plus the magnetic strength. And they need to be physically touching, no gaps between them. Where did you get your magnets? The only Halbach style I found(didn't look real hard though), was 20mm outside diameter. I'm a retired tool maker/ machinist and have tried to machine magnets and there not easy.

The blog link guy shows a magnetic analysis of the different magnet structures.

Please keep us updated on your progress.