[glaurung]

I´ll have to comment that my XJS will have dual 11". Very nice XK
Harri

[Yabert]

Personally, I think this sort of "promotional" car must have impressive performance!... So, go with DC 300v 1000A!

If you make a car with ordinary performance, most people will think that Kostov motors offers ordinary performance.

Instead, if you manufacture a high performance car, people will say: What motor it is there inside? The Answer will be Kostov and after this will those people will choose Kostov motor (any kind: DC, AC, 9" or 11"). A bit like many people choose the soliton Jr because they was impress by the performance of the soliton 1.

The high performance things naturally impress the human!
Instead, high range (200-300 miles) or high efficiency only impress a fraction of people.


And if you think going for high performance, 90 thundersky battery isn't the answer! You need better powerful cells.

[Plamenator]

I really do not want to make this into another DC or AC thread.
I know that a brushed series excitation motor is almost impossible to beat under 250V by a similarly sized AC one. After all series DC motors are my first love... They have proven the perfect toy for enthusiasts.
Yet brushed DC has its limitations - high rpm are a problem, no regen, impossible to isolate properly from the elements, unsuitable for water cooling and unsuitable for high voltage.
So despite their stellar performance, no serious auto producer has adopted them so far.
Yabert is right that my AC design will be mediocre and inferior to a 300V DC set.
But such promotional DC cars have been done over and over yet they have failed to promote brushed DC technology.
If I decide to use AC, it will be with the purpose of seeing just how "bad" AC can be with the currently accessible low voltage AC controllers.
So I would really appreciate your comments on how to make my AC setup the best possible. Have in mind that Curtis is prototyping a new 144V controller - 2 of those with a dual motor can give any DC the run of its life. And it does not need to cost ridiculuously more than a DC combo while offering water cooling and regen.

[Qer]

Then it seems you've already made up your mind and that the threads subject is misleading.

[efan]

Originally Posted by Plamenator

I really do not want to make this into another DC or AC thread.
I know that a brushed series excitation motor is almost impossible to beat under 250V by a similarly sized AC one. After all series DC motors are my first love... They have proven the perfect toy for enthusiasts.
Yet brushed DC has its limitations - high rpm are a problem, no regen, impossible to isolate properly from the elements, unsuitable for water cooling and unsuitable for high voltage.
So despite their stellar performance, no serious auto producer has adopted them so far.
Yabert is right that my AC design will be mediocre and inferior to a 300V DC set.
But such promotional DC cars have been done over and over yet they have failed to promote brushed DC technology.
If I decide to use AC, it will be with the purpose of seeing just how "bad" AC can be with the currently accessible low voltage AC controllers.
So I would really appreciate your comments on how to make my AC setup the best possible. Have in mind that Curtis is prototyping a new 144V controller - 2 of those with a dual motor can give any DC the run of its life. And it does not need to cost ridiculuously more than a DC combo while offering water cooling and regen.

I agree that DC has been done over and over, and you should therefore go for an AC setup. With that said, you should try and get your hands on that 144v Curtis controller.
One question that I have is, what kind of torque curve do you expect from the AC motor that you are planning to produce at 144v (500a ? controller)?

[Plamenator]

Originally Posted by Qer

Then it seems you've already made up your mind and that the threads subject is misleading.

I am heavilly leaning on AC indeed but not yet 100% decided.
I guess I am too interested in my new toys.
(Soliton3 sounds like a good name BTW )

The new Curtis controller is expected to be 144V/550-650A but it could be a few months or a year away from market. I am desigining the car so that it can be upgraded to 144VDC later on.

Torque curve is more or less standard.
I have attached a rough sketch of the torque of 18AC9":
http://kostov-motors.com/tractionmot...es/18ac9100hz/
In fact we managed to go to 180Nm at one point but motor smoked in 5-6sec.
The new motor will be significantly bigger but shape of curve will be similar. I hope we can safely get the 180Nm on this one.

[steven4601]

Hi ,

What about cooling the motor with water/oil? Cool the stator windings so they can be used way further than 5A/mm2 for short bursts. A step further is assembling the motor so that very thin oil can be run through the motor from back to front cooling also the rotor. The only design snatch is to put enough kevlar on the rotor and yet make it smooth enough so the oil cannot find cavities on the surface to build up unwanted pressure/friction.

[Plamenator]

I would stay away from oil cooling of the rotor but stator water cooling is definitely in the plans once we develop the AC range.

Unfortunately we do not have much experience with water cooling.
I was hoping that someone would be selling ready made jackets like in the picture. However I cannot find such jackets that would be both aluminum and big enough (internal d=200-240mm; the one in the picture is by Leopard and meant for very small hobby RC motors and not at all sure it has a double wall).

[steven4601]

Cooling jackets as you call them are basically press fits / interference fits one tube over the other. The inner tube is may have a maze pattern in it for maximum surface area. Other solution is to use two tubes and two bolt-on flanges. Those flanges could also house the bearings, rotor sensor etc.

What about 'axial flux' motors like YASA tries to license as a design? Axial flux motors where already in 1970's computers floppy drives..... No law suits ever can be started over that kind of technology.

[Salty9]

Have you considered lost foam aluminum casting? I've lost the thread but some Canadian had a detailed procedure for diy aluminum casting.