[ruckus]

This motor/controller combo looks very nice!

Cheers

[bjfreeman]

Originally Posted by njloof

Because you can't excite all three windings independently?

Current is controlled through motor terminals one pair at a time, with the third motor terminal always electrically disconnected from the source of power.

Three Hall devices embedded in the motor are usually used to provide digital signals which measure rotor position within 60 degree sectors and provide this information to the motor controller. Because at any time, the currents in two of the windings are equal in magnitude and the third is zero, this method can only produce current space vectors having one of six different directions. As the motor turns, the current to the motor terminals is electrically switched (commutated) every 60 degrees of rotation so that the current space vector is always within the nearest 30 degrees of the quadrature direction.

here is a technical comparison that also is implemented on cpu.
http://www.magnelab.com/uploads/4c51d9ba6fe5a.pdf

[njloof]

Right. I understand the trapezoidal control scheme; I want to understand what prevents you from using a sinusoidal control scheme with a BLDC motor. Is there no ground terminal?

[bjfreeman]

My understanding is, it is a wye configuration.
unless there is something about the physical windings, a FOC controller can be used with a couple more connections for Voltage sensing.

Edit on second thought I believe you right.

[aeroscott]

Would trapezoidall control be commenly used on rc airplanes and also in maned electric airplanes , bing that low rpms are of little consern with a propller .
Would the Prius controller be a quadrature (I ment field oriented control).

[Tesseract]

The windings are distributed among the stator slots differently for the two types of motors. You can apply a sinusoidal PWM pattern to both types of motor, but that is not going to change a trapezoidal type into a sinusoidal type.

[Bowser330]

Originally Posted by ruckus

Umm.. not to give away any secrets, but the "Scott Drive" is actually a Chinese BLDC motor that I have been thinking of importing for use in my next build and to sell in the U.S. (since the U.S. does not produce a liquid-cooled BDLC motor).

Considering the crazy shipping from NZ and the extra middle-man, I am guessing folks would rather just have it shipped direct from China to the U.S. at significant savings.

I am currently "bargaining" with the factory over the price breakdown for bulk orders. If anyone is interested in joining a bulk "beta" order, let me know. I hesitate to put my name behind the product until I have fully tested it and it has "proven up".

Cheers

Can you share the information about this "Chinese BLDC motor"?

Very similar specs and measurements to these motors that have popped up on this forums for awhile now...http://en.glelec.com/cp.html (Shenzhen Greatland Electrics)


http://www.epowertransfer.com/UploadFiles/ehug.pdf
shows specs of the motors, much more info than the Shenzhen page..same products...
The specs on the "MP25L0" 30kw cont. 60kw peak (100kw for 10 sec?) 4000rpm max motor weighs 88kg again figures close to the 80kg listed for the Scott Drive.

An even more interesting model is the "MP20L0" 30kw cont. 50kw peak (90kw for 10 sec?) 9000rpm and only 68kg.

[njloof]

Originally Posted by Tesseract

The windings are distributed among the stator slots differently for the two types of motors. You can apply a sinusoidal PWM pattern to both types of motor, but that is not going to change a trapezoidal type into a sinusoidal type.

Ok. Good to know.

I suppose I should find some small surplus motors somewhere I can disassemble so I can understand the windings a bit better. But for now, this will do

[ruckus]

Hello,
The Glelec and epower are one in the same. Identified by the cooling ports being "in-line". They look well made, but their torque-to-weight ratio is not as good as the Scott.

[Bowser330]

Originally Posted by ruckus

Hello,
The Glelec and epower are one in the same. Identified by the cooling ports being "in-line". They look very well made, but their torque-to-weight ratio is not as good as the Scott.

There are 2-3 other water-cooled BLDC motor cases floating around China. The "Scott" is different from the Glelec. Identified by the cooling ports being one at the top, one at the bottom coming off tangentially. About 4 companies "claim" to make this motor. A bit tricky figuring out who actually does. The advantage of the motor used by Scott is that if you dig deep enough you can find it rated for 540vdc (I'd still rather have 640v). This gives a LOT more torque from the same motor weight. That is the direction I am looking to go.

There is one other with the cooling port coming out in the middle like a belly button. But it is a bit small by American standards.

I don't want to go into too much detail since I am trying to bring these motors to market in the U.S., but I can say that I am now talking with the friendly folks in NZ at well. I see collaboration as the way to bring the prices down and get EV's into the mainstream.

What is your timeline on bringing them to the US market? I didn't see any update on your website.

I like the sound of bringing prices lower than the already shown 6,000$.