[ruckus]

Well, a couple of things... remember that grain of salt I was talking about?

20% is a very standard power loss factor used when roughly converting kva to kw. If you go to generator sizing calculations you will see it used often.

The controllers are measured in kva and the motors in kw. 20% is a very rough estimate of the TOTAL losses in the controller and motor at max power. (Let's not forget battery sag while we're at it). This is standard industry practice when sizing drive systems for a given duty and says nothing about the efficiency of these particular motors.

These are not dyno charts! They are merely pictoral representations of the motor specs already given in number form.

[jk1981]

Originally Posted by Tesseract

As a result of these severe shortcomings, trapezoidal BLDC is really only suitable for small fans and servos, not traction applications.

Why aren't brushed-DC motors subject to the same torque ripple that makes trapezoidally excited BLDC so unsuitable for traction applications? Where is the big performance difference between a Hall-sensor+inverter commutated BLDC and a mechanically commutated Sep-Ex that makes one 'unsuitable' for traction and the other a well established norm

[PThompson509]

I wouldn't say BLDC is unsuitable for traction motors - I've got an 80kw motor in my car and it seems to work fine - other than the blown IGBT in the controller....

[Tesseract]

Originally Posted by jk1981

Why aren't brushed-DC motors subject to the same torque ripple that makes trapezoidally excited BLDC so unsuitable for traction applications? Where is the big performance difference between a Hall-sensor+inverter commutated BLDC and a mechanically commutated Sep-Ex that makes one 'unsuitable' for traction and the other a well established norm

Brushed DC motors DO suffer from torque ripple, but the number of commutator segments is high enough to approximate a sinusoidal flux distribution, which both flattens out the torque ripple amplitude and minimizes the angular error between the direct and quadrature fluxes.

Originally Posted by PThompson509

I wouldn't say BLDC is unsuitable for traction motors - I've got an 80kw motor in my car and it seems to work fine - other than the blown IGBT in the controller....

I was referring to a specific type of BLDC motor, not BLDC motors in general.

[ruckus]

Originally Posted by PThompson509

I wouldn't say BLDC is unsuitable for traction motors - I've got an 80kw motor in my car and it seems to work fine - other than the blown IGBT in the controller....

Care to share what type/model/voltage you have and how it has worked for you?

Thanks!

[Bowser330]

Originally Posted by ruckus

Care to share what type/model/voltage you have and how it has worked for you?

Thanks!

http://www.diyelectriccar.com/garage/cars/224

- Drivetrain -
Controller: GLCP7024L11
Motor: GLMP25L1
Battery Pack Voltage: 349v
Other Notes:
Updated to different BLDC motor from Greatland Electric

[PThompson509]

Yup, that's me. My 914 mechanic LOVES the acceleration. I'm really hoping that nothing serious went in the controller - I'll find out on Sunday - a coworker that has repaired these sorts of things is stopping by. I'll keep you posted.

Cheers,
Peter

Originally Posted by Bowser330

http://www.diyelectriccar.com/garage/cars/224

- Drivetrain -
Controller: GLCP7024L11
Motor: GLMP25L1
Battery Pack Voltage: 349v
Other Notes:
Updated to different BLDC motor from Greatland Electric

[Jan]

Originally Posted by Tesseract

I was referring to a specific type of BLDC motor, not BLDC motors in general.

In this thread is suggested that the remy is also trapezodial....?

[Tesseract]

Originally Posted by Jan

In this thread is suggested that the remy is also trapezodial....?

That does seem to be the suggestion, but don't confuse a trapezoidal PWM scheme with a trapezoidally-wound motor; the two go together, but they aren't the same.

[Jan]

Originally Posted by Tesseract

That does seem to be the suggestion, but don't confuse a trapezoidal PWM scheme with a trapezoidally-wound motor; the two go together, but they aren't the same.

Yes, that's what I understood out of your first comments. This is a trapezoidally wound motor, and the controller can't change that. But it is still what the linked thread suggests: The wavesculpter he coupled is perfectly able to provide a sinesodial (gesus what are these words hard) scheme as far as I know. Is he wrong? Or don't I understand what he means.