1. In your graphs you show the "Stator T". but you installed thermistors on the stator AND under the copper/winding:
So are you also capturing/representing data for the copper/windings temp or just the stator, or are you somehow combining them? I'd be curious how close those temps are, and how much the windings temp fluctuate in comparison to the stator.
Hey great question. I'm only looking at the copper temp. Early on I measured them both briefly and they were within a few degrees, but that was after the motor had been stopped and settled a bit so perhaps during the run when most of the watts are originating from the copper that there is more of a differential. I'll find out next run.
2. Do you know why the Stator T drops so much more than the model when the motor is running at 400 RPM?
Yes indeed, it's because the thermal conductivity with both side holes open is no longer linear with RPM. In the model, I've just got a straight line 1/R vs RPM dependancy for each of the 3 resistance terms. If I change that relationship slightly so that the lines cross the 400 RPM data points, then the model will be spot on at 400 RPM but show even larger errors at the other RPM's. If I change the model so that the conductivities have a 2nd order RPM dependence, then I think it would match spot on over all the speed ranges. I may do that later this evening.
Can you say more about how you are calculating the model(s)? Do I understand correctly that one of the goals of this project is to create models for each type of cooling method for use in the simulator? If so, will there be specifications for each technique, like "30 1/2" holes around the perimeter".
That's indeed one of my main goals, although it would have to be understood as 'ballpark' in terms of choosing the technique. Say one option for holes on one side, another for holes on both sides, and another for holes with blades. That's part of why I want to see how much of a role little variants play. The model itself is based exactly on this:
Where the 1/R1, 1/R2, and 1/R3 terms all vary linearly with RPM based on the steady state temperatures, and the heat input is calculated from the temperature corrected I^2R copper losses plus the hystersis/eddie core losses at that speed based on the no load current data.
3. Finally, can you explain how the simulator currently calculates the "Overheats in: XX min", specifically what temp represents overheating? 80C?
It's 150 degrees, as explained in the FAQ text under the simulator. But it's based on a static non-rotating motor tests and doesn't seperately take into account the stator vs the shell, so is only intended to provide a ballpark relative figure and not to be taken literally in any ways. The main goal was just to give people a reality check when they plug in a 96V 60A setup to a hub motor and see many kW of power and go SWEET! That's what I want!
That's another set of tests that needs to be resumed too, and brought into the simulator model. In the meantime, we've been meaning to make the lines go fuzzy or vanish when the model is predicting a phase current that is higher than the saturation point of the motors, so that people again won't take that literally since it's out of the bounds for what is modeled.
Previously competed in the Suntrip race on a back to back tandem solar powered row/cycle trike
. 550 watt solar roof, dual Grin All Axle hub motors, dual Phaserunner controllers, 12 LiGo batteries, and a whole wack of gear.
Now back in Vancouver learning to be a dad with my Big Dummy Frame (yes This One
, thanks ES!) with GMAC 10T rear hub motor, Phaserunner controller, and 52V 19Ah EM3EV pack
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