View Single Post
Old 05-29-2021, 01:08 PM   #105
hk 40
Join Date: May 2011
Location: RTP, North Carolina

Just do the math, it's not as easy as you have written it. The efficiency is the factor for higher power throughput.

An example
Assume that the motor has an efficiency η = 0.900 and can process an input power of 5.0 kW. This means that (1 - 0.9) 5 kW = 500 watts of excess heat can be dissipated. By pressing in thicker wire (and / or using better segmented stator iron magnets) the efficiency increases to 0.933. The motor's ability to lose those 500 watts has not changed (through radiation, convection, and conduction). This means that the motor can now handle 7.5 kW before it reaches the loss limit of 500 watts (0.066 7.5 kW).
An efficiency from 90 to 93.3% means an increase in performance of 50%, a factor of 1.5. This is why efficiency plays such an important role in every motor concept: the efficiency determines the maximum output. All of this on the assumption that the iron is not saturated.
A pretty extreme example, just for computational / fun reasons: an increase in efficiency from 80% to 90% would increase the input power the motor can handle by a factor of 2. However, if the efficiency can be increased from 90% to 95%, the input power also increases by a factor of 2.

General case
A change from efficiency ηold to efficiency ηnew would result in an increase in the maximum engine power by a factor of N.
N = (1 - eta old) / (1 - eta new)

Copper as thick as possible for ...
higher efficiency
more efficient
lower speed drop under load
lower losses
lower temperature requires less cooling

For testing the same engine sizes e.g. Define a power, for example 35 volts and 100 amps, and tape off all cooling options (tape tape around the fan openings and the motor to a plywood sheet, against heat dissipation e.g. with aluminum). Let the motor run at this power for 2 minutes and then immediately set the temperatures at different Measure places. Therefore set the cooling to zero if possible, otherwise a better cooling fan design keeps the motor cool but the power loss can still be quite high. Otherwise you wouldn't recognize that.

~ Christian Lucas ~

My colleague and German brother that holds several patents in aviation instrumentation, electric motors, and fuel cell technology. Be careful with the phone world on turbobricks way that doesn't believe striving for top efficiency is always a goal with any EV worth a flip. A hobby wont be much fun that way.

I watch with interest, and I hope this is clear and concise enough for the EV and electric motor experts you may encounter here on turbo bricks. Efficiency and weight has no place in your discussions about EV's with them, U see they push it out the truth, but I think you should seriously consider it from the information uve been provided above if you are indeed an engineer. Especially if you want maximin fun that last..... What I've written should be crystal clear to you. They don't understand that most motors you find in the junkyard wont have the new wind tech therefore you can implement it and have a motor with theoretically half its original iron losses. We spent 7 years proving it to other engineers, I wont waste another 14 with the smart people on TB. Anybody that truly understands this wont require much coaxing because all they have to do is review the math. To say 19 points of efficiency wont make a difference in your fun Is a huge overcite! I also don't think you'll have much fun at 42 hp.


Last edited by hk 40; 05-29-2021 at 01:38 PM..
hk 40 is offline