Quote:
Originally Posted by e*clipse
This is more of a question, specifically aimed at Thingstodo or anyone with lots of electric motor experience.
|
Thanks for the vote of confidence
Quote:
Toyota puts a limitation of 50kW on this motor; it would be interesting to figure out how they reached that number, and how far one could push past it. Because there is no external heat rejecting device (radiator) the case of the MGR must be able to dump more than 50kW - the motor's waste heat in addition to the gear and bearing inefficiency.
Ok, after that long introduction, Thingstodo - do you have any way of calculating the maximum current one could subject the stator to? I know you did that test on a copper wire - that was extremely interesting. I **sort of** have the winding specifics - we may be able to figure out the maximum current for a short time.
Seriously, a short time like 10 seconds (with adequate cooling) could allow a radically different amount of current (thus power).
|
Short answer - I can't think of a way to calculate a max current, or a max USEFUL current, I guess. DC current is just V/R but that's not useful in spinning the motor.
A 10 second burst of power will heat things up for sure. Toyota has put a lot of engineering into this unit. In the interest of costs, their controller may not be ABLE to push too much current for longer than the motor can take it. At design time, which was a few years ago, the electronics would have been the most expensive part.
If it were my MGR that was being tested, I would:
- pump in 50 KW for 60 seconds
- run the system at idle and measure the changes in heat for the next hour or until temperatures return to ambient
- pump in 75 KW for 60 seconds
- run at idle and monitor
- repeat every 25 KW on up until you reach a limit.
The limit may be the insulation on the stator, the temperature of the magnets, the smell of varnish being burned off the outside of the housing ...
I have gone through ebay.ca and have not found any MGRs ... perhaps I don't know how to looks very well?