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Rwinding 0.145 Ohm kV 0.097 V/RPM C_stator 1400 J/deg C_shell 1100 J/deg 1/R_stator 3.50 W/deg 1/R_shell 3.00 W/deg
Yes, actually I'm doing that in quite a separate set of experiments. With this particular controller having a sinusoidal output, the switching losses are 2-3 times higher than you'd get with a standard 6-step trapezoidal drive, and you get switching losses all the time, even at full throttle with no current limiting.adrian_sm wrote: Looking forward to your results. Would be interesting if you could also monitor your controller temperatures, if you run them in current limitting/partial throttle for sustain runs.
Yes, most definitely. I was going over your other threads with quite some interest. If you can sketch or draw what you think would be the ultimate fan/airflow design for the 9C style motors then give a description and we've got all the tools to fabricate it. At the moment, I'm planning to compare:John in CR wrote: Please let me know if you want any input with bladed strategies. i've done significant research and experimentation, and airflow systems design is a lot more than putting holes in a side cover.
This is the old rounded style. It leaves a fair bit more room on the inside between the stator and the side plate than the newer disk motors, so will be more suited for adding internal fins.John in CR wrote:Justin,
Which style of 9C covers are we talking about, the old rounded ones or the new style with square edges? If the new style I need to see a pic of the inside of the covers.
You mean running some smoke to visualize the airflow? That's not a bad idea. We have a small handheld anememoeter for quantifying flow rates but it doesn't work so well on a spinning reference frame. But if a setup has clear intake holes, then you could have large diameter pipe that fits over all of them and then measure the flow rate through that pipe to quantify how many L/min of air is getting pushed through the hub.Thanks for doing this BTW. I should also give me an extra push to finish a current project and get some video using a dense smoke machine my friend has. I'm running a sealed high efficiency motor now or I'd just send some smoke through it.
There's definitely an exchange of fresh air regardless, the interesting question is just how much this gets improved by the addition of features to force the convection much further, and that's what the finned build as per your suggestions will help us nail!My interpretation of the test so far is that the stator still gets too hot, because there's no reason for an actual intake and exhaust flow to take place. The trailing edges of those large holes create more turbulence right at the windings, and probably more spinning action overall. There may be some exchange of fresh air, but I think it must be limited.
Yeah 120 degrees is not something you want to design for, but the copper windings handle it fine and doesn't risk burning the enamel. I would be nervous if the magnets got that hot, but they are thermally linked to the rotor which is a lot cooler throughout the tests.PS- Don't you think 120°C is way too hot? The factory I get my motors from install a thermistor with a 95°C trip point. It is installed on the stator about 1cm from the copper, but for your continuous running that shouldn't make any difference.