[ruckus]

Originally Posted by Arlo

...the efficiency drops as your raise the power imput the only way to know how much is to run dyno tests.

I certainly agree. That is the plan.

Originally Posted by Arlo

I also think the motors seem heavy for their rated power...

Really? An 11" series DC motor weighs 106kg and is only rated at 26kw. This is 85 kg and has more than double the rating at 55kw.

So 2X the power rating at 75% the weight. Doesn't see bad to me..

[DavidDymaxion]

That is a pretty good power to weight. Another comparison is the power and weight of the Kostov 11 alpha is 50 kW and 75 kg.

To be really fair, the comparison should be motor + controller weight, as DC does commutation mechanically inside the motor, and AC does it in the controller. How much does the Scott controller weigh? For Kelly controllers the BLDC and Series motor controllers are pretty close to the same weight.

Originally Posted by ruckus

... An 11" series DC motor weighs 106kg and is only rated at 26kw. This is 85 kg and has more than double the rating at 55kw.

So 2X the power rating at 75% the weight. Doesn't see bad to me..

[Jozzer]

Originally Posted by ruckus

I certainly agree. That is the plan.



Really? An 11" series DC motor weighs 106kg and is only rated at 26kw. This is 85 kg and has more than double the rating at 55kw.

So 2X the power rating at 75% the weight. Doesn't see bad to me..

Power density isn't THAT good - compared to a high end AC drive. For example EVO - 128kw continuous from a 57kg motor.
http://www.evo-electric.com/products/electric-motors/

And to compare it to a DC series motor for continuous power density isn't very fair - Series motors are NOT well known for high continuous power, but high overload/peak power. That 86kg Kostov mentioned above can peak at over 300KW easily for short bursts (and at nearly 50kw continuous it's not far behind your ScottDrive there either).
Also agree with Arlo that efficiency of the motor under extreme load will be much lower than you think, and same goes for the controller..

[Arlo]

This 12kw liquid cooled motor weighs 11 lbs I plan to be using a chassis dyno soon. Unfortuanatly its a very hard to run motor and only some of the expensive controllers can run it. So Im building my own controller for it. http://endless-sphere.com/forums/vie...p?f=30&t=16728

But when you have permant magnet AC motors and their liquid cooled I would expect them to be a lot more power dense then a series motor like an order of magnatude. Also check out the soup can sized motor for the BRD motorycle guys it makes 46hp rear wheel.

[PStechPaul]

What must be taken into consideration is that higher horsepower can be achieved by high RPMs with the same torque and current at a higher voltage. Up to a limit, of course, which depends on the commutation frequency, and insulation resistance at higher voltage.

But when you try to get higher torque the current goes up proportionally and the resistive losses go up by the square of the current. So a 90% efficient motor at 100 amps will have 9 times the losses at 300 amps so efficiency is down around 10%. Liquid cooling will help some, but it is difficult to cool all of the motor parts, and the piping and extra components for coolant pump and radiator add weight, cost, and expense. The liquid cooling will only allow you to run the motor at higher power for a longer time before it burns up, and does not increase HP output.

I was not that much impressed by the video. You can burn out a bike tire with less than 1 HP. And the 300 amps at 100 volts is 30 kW or 40 HP into the motor. At 20% efficiency it's only about 8 HP to the wheel.

[Dennis]

It is too bad that no one is using 400 Hertz 3-phase AC induction motors as used in aircraft as hydraulic pumps for EV conversions. There has been many forum posts of these high frequency design 3-phase motors, but they simply get buried away. I guess for the DIYselfer it is nearly impossible to source a 400 Hertz 3-phase motor, not to mention an appropriate controller. Baldor was kind enough to provide a 50 HP, 60 Hz, industrial motor for the EV community to purchase. Now if they can just build a 400 HZ version, so it will weigh about 50 LBS instead of 490 LBS... We the little guys though, so I do not see this happening.

[PStechPaul]

The size and weight of the motor is not the major concern for EVs. It is quite possible to rewire a standard 240 VAC 6 pole 20 HP motor for 138 VAC and then overclock it to 180 Hz and 415 VAC to get 60 HP at 3500 RPM, which matches the ICE speed and torque pretty well. You should start with a high efficiency motor which will be somewhat bigger and heavier, but still it will be only about 150 lb which is less than the ICE. And you can safely get 2-3 times the torque for short durations as needed. The 400 Hz motors are specially made from very thin special steel laminations, which are very expensive, and they are also usually 10,000 RPM or more, which is not compatible with the drive train of the donor vehicle.

The battery pack is by far the largest, heaviest, and most expensive part of the build. An exotic motor is not really necessary, and the initial cost as well as compromises in ruggedness, maintenance, controller complexity, and reliability "outweigh" these amazing but often unrealistic and impractical little motors.

[JRP3]

Originally Posted by PStechPaul

The size and weight of the motor is not the major concern for EVs.

It is with the 490lb Baldor motor he mentioned.

[somanywelps]

The YATA-400 motors seem to fit this better than the chinese BLDC...

[PThompson509]

Do you have a link for anyone that sells this motor? I'd love to look at the specs.

Cheers, Peter

Originally Posted by somanywelps

The YATA-400 motors seem to fit this better than the chinese BLDC...