[Madmac]

If I may suggest we also set the goal of keeping the cost of the final system as low as possible so that most people will be able to afford it.

Going for a hub motor instantly increases the cost. A single motor with controller will always be cheaper. It is also a bit more reliable.

What would that cost be, by chance? I'm interested, but I can't develop firmware under the "no commercial use" clause.

Difficult to give a price at this point. I have not been designing for least cost that is for sure. I am designing something that will do more than commercial systems at far less cost. With regard to no commercial use. I have put designs in the public domain before and ended up seeing them being sold for profit. I have no issue with a commercial operation as long as they do not exploit. In my case a good contribution to charity's that can be publicly verified would be fine.

Madmac

[manic_monkey]

i think 40kw per wheel may be a little extreme. as a drive train motor, thats probably fine, but as a hub motor that would be 80kw 2wd, or 160kw for 4wd. at this point i would say that we should forget the controller, and focus on the motor.

I agree that a neodymium outrunner seems to be the way forward. My only concern is the cost and sourcing of magnets in the right size might make an AC motor look like a better proposition.

what i would really like is some discussion on physical motor size; especially the stator depth / width. i believe that the stator size is related to the max power of the motor (or at least the maximum efficient power of the motor) due to magnetic saturation. also, where the motor is to be mounted will most likely effect the possible size.

[John]

Originally Posted by judebert

Let's just modify #4 to specify the sorts of electric current allowed: The drive system shall recharge the energy storage system from 120V 60Hz single-phase AC, 240V 60Hz three-phase AC, or DC current from 120V to 240V.

Don't forget most of Europe, and Australasia, (just to mention a few places) use 240v single-phase at 50Hz (and 415v three-phase). Think outside of North America this is after all the world wide web.

[Manntis]

Originally Posted by John

Don't forget most of Europe, and Australasia, (just to mention a few places) use 240v single-phase at 50Hz (and 415v three-phase). Think outside of North America this is after all the world wide web.

that said, North America remains the world's largest car market and provisions for a smart charger that can take either 120V or 240V will make any EV project more viable

[John]

Originally Posted by manic_monkey

i think 40kw per wheel may be a little extreme. as a drive train motor, thats probably fine, but as a hub motor that would be 80kw 2wd, or 160kw for 4wd.

I think power in this application is a bit of a distraction from what is the most important parameter to consider which motor torque is. You have no gear reduction to amplify torque so what the motor produces is what you get and that coupled with the rolling radius of your wheels determines your driving force which in turn coupled with the vehicle weight decides your grade-ability and acceleration and also how effective your Regenerative Braking will be. Most direct drive systems require huge amounts of power to meet their torque requirements across their required rev range. A regenerative only braking system would require vastly more than 160kW (see post 51 of this thread).

[3dplane]

John!
About no gear reduction: in post #74 I made an attempt to explain where the torque comes from in an outrunner.It's like an invisable planetary gear set.And it works! My "slowest" motor (32 poles=16:1) when I did the first runup test I laughed at the rpm at full speed (about 360rpm at 12v) and casually grabbed the bell to stop it, well, it twisted the motor out of my other hand holding it! The only limiting factor for rpm would be the controller's ability to fire the phases fast enough.That said, when we upscale motors like this the whole inductance thing might require the controller to be nothing like the one for the tiny motors.(thats the part where I'm pretty clueless) That is another reason I'm waiting for GRAVITIC ANOMALY TO COME BACK (I hope he heard that) with some info on that two footer he built.
Manic !
No secrets. While hanging around windmill sites(web) I saw people using Fisher & Paykel washing machine motors for generator.They are basically huge outrunners. I did not really look into them but maybe you guys could do that. Criteria!: the number of arms on the stator has to be divisable by three! to make a motor for our purpose. If stator lenght(pancakeness) is not sufficient identical stators can be stacked to make a longer more powerful motor. Barna

[Bugzuki]

Well, I have been busy and missed this thread until now. I might have missed something in the previous discussion.

What type of motor: 3-phase AC induction. I think that it would be impossible for the general public to come up with the magnets needed to build DC or BLDC motors. Those magnets would have to be formed to the shape of the motor and not just cow magnets. The are other benefits also like regen.

Mechanical brakes: Yes. I am pretty sure that every state requires mechanical brakes on the car (State Law). The brakes could be setup to only apply after a certain amount of pedal travel and upto that point it would be all Regenerative Braking.

Controller location: Out external to the motor. This would minimize the unsprung weight and also allow the controller to be isolated from the road vibration. You would only need the three power wires and the speed sensor wires going to the wheel.

Motor Configuration: I was thinking that it would be cool to have a inside-out motor, but I think that it would be the lest costly to have the normal configuration with the squirrel cage on the inside. This way the rotor could have a hub mounted to the outside and the brake rotor could be mounted to that with the wheel - in the current configuration. The the brake caliper could be mounted to the stator housing.

The back side of the stator housing could be designed in a generic fashion to allow different attachments to different suspension systems.

Suspension: This might be an issue. If a front wheel drive car is used the rear suspension might not be strong enough to handle the acceleration forces. The do see braking force, but that is much less since the rear lifts during hard braking. The only way to find out is to try it.

Mechanical Design: I currently have a fully licensed version of Pro/Engineer WildFire 3.0. So, I could do a lot of the mechanical design for this project. If you guys want. I do want to inject a thought here. If someone were to have an none licensed version of some software and they used it for a project like this that software manufacturer would have the right to sue and maybe get the designs destroyed.

Controller Design: I have been working on a 3-Phase AC controller design - slowly. I think that the best option would be to use the Microchip controller that they have specifically designed for AC motors. I could share what I have so far.

Something for me: I would be willing to do this in return for your guys help getting the design together. I would probably be less inclined to contribute to this project if it had a strickly non-commercial clause. I would like to put together kits for various cars and be able to sell them.

Manufacturing the Parts: In order to get good deals on manufacturing it is very important to have larger quantities together in one run. If we could pull this off and have group buys that would help us lower costs.

Education/Experience: I have an Electrical Engineering Associates Degree(Skagit Valley College), and a Bachelor's Degree in Industrial Technology/Vehicle Design from Western Washington University. At WWU I was the Team manager for the Viking32 Government project - Natural Gas/Electric Hybrid. http://www.hybridaction.com/viking32/general.htm I then went on to be a Design Engineer, Manufacturing Engineer and Liaison Engineer for Kenworth Truck Co. (only automotive company here in Seattle). I am currently the CAD administrator for Philips Ultrasound (huge layoffs in the trucking industry last year).

I am not the best Electrical engineer, so would like help on that part of the design. I have some embedded systems programming experience, but again am far from an expert.

Hopefully we can get this project moving.
Paul

[John]

Originally Posted by 3dplane

No secrets. While hanging around windmill sites(web) I saw people using Fisher & Paykel washing machine motors for generator.They are basically huge outrunners. I did not really look into them but maybe you guys could do that. Criteria!: the number of arms on the stator has to be divisable by three! to make a motor for our purpose. If stator lenght(pancakeness) is not sufficient identical stators can be stacked to make a longer more powerful motor. Barna

The F & P motor I have has 42 arms. I think they also do one with 36 for their decogged motor. The magnets are I think a bit weak. The controller rectified 240v AC single-phase and then inverted it back to three phase switched positive and negative to drive the motor.

[Bugzuki]

Controller idea - I was planning on having a multiple controller system as mentioned earlier. One main controller to do all of the communication with the driver and vehicle, then is sends the commands to the individual motor controllers. The motor controllers just keep track of the motor and send status reports back to the main controller.

I was designing the motor controller first with the idea that it could also act as a stand along controller - with limited driver interface (just acceleration, braking controls and status reports like speed and operating temperature ...).

With the Microchip controllers the code could be done in C so it could be edited by anyone that knows C.

I am planning for a LCD display for on the dash to give the driver the information needed about the system. I also wanted to try to tap into the instrument panel and control the tachometer, speedometer, temperature gauge and whatever else.

If done correctly the controller would be able to control the power put to the wheels. So, if we designed the motors capable of 40 or 50KW then if you did not want all of that power you could just adjust a variable in the program to produce less. Then later if you got more batterys you could have more power. So, have a total power percentage variable that could be set at runtime. Using that Horsepower conversion from earlier, I would rather have 216 hp available when I wanted it then 100hp.

[Bugzuki]

One more thing - with BLDC motors there is a larger chance of injury while assembling and disassembling the motors. The rotor really wants to be inside the stator and requires a press and a lot of care to get it out. We had to deal with that when we replaced the end cap on the Unique Mobility motor we used on Viking32.

Don't to get sued for injuries on an open source project.