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23 Posts
Hi everyone, I've been lurking here for the better part of 2 or 3 years and want to integrate into the community a little bit more. I'm not as much of an expert as I'd like to be but I've got project ideas that could use a few tips.
I like brush-less motors and am reasonably familiar with 3 phase control of them but I find a lot of the really important design critical motor feed-back type stuff is often left as an exercise to the reader. For instance, how to tell if a motor is trapezoid or sinusoid type in its design scheme. Its frustrating to say the least.
I also understand there is a fairly wide price gap between a high performance AC motor (used here to mean brush-less DC as well) and the second or third hand industrial motors and small hobbyist variants, for reasons that seem rather trivial.
I wanted a to select a motor that had at least stator cooling (shaft cooling would be awesome, but I don't know if there is any way to acquire those outside of parting out a Tesla, (which I read is permanently affixed to its reduction gear/differential) Which is looking to be both too large, and unsuitable for my application.
I wanted to try my hand at a differential steer/differential drive. using 4 independent wheels and...for lack of there being a good/cheap/available motor. I was wondering if anyone had any thoughts/cautionary tales about using hobbyist RC motors stacked into planetary arrangements to drive a lighter weight vehicle directly. something like a hub motor arrangement (though my project will be a tad different mechanically)
I know of 2 issues with this. firstly, its wasteful volumetrically to have 5 or six motors where 1 large motor would have worked. this is irreducible but I figured it may offset some of its shortcoming because the individual motors are pretty high performance for their weight and have good balancing and performance properties. The second issue is that RC motors of the power you'd need to power a vehicle, even working 6 or 8 in tandem per wheel, need to be beefy indeed. 5 or 6kw continuous at a minimum, if you want a vehicle of even modest performance.
there is a third issue about vehicle dynamics at low speed causing excessive wheel hop. I think the only way to reckon the correct wheel geometry is through experimentation.
Here's the stuff I would like some advice on: Never attempted regenerative breaking with a bldc motor and controller of the hobbyist type...doubt many have either. I also know many prefer these motors to be very (overly) simple, lacking hall sensors and encoders etc... and the controllers themselves may prove unsuitable. Anyone have any thoughts into this sort of arrangement?
I like brush-less motors and am reasonably familiar with 3 phase control of them but I find a lot of the really important design critical motor feed-back type stuff is often left as an exercise to the reader. For instance, how to tell if a motor is trapezoid or sinusoid type in its design scheme. Its frustrating to say the least.
I also understand there is a fairly wide price gap between a high performance AC motor (used here to mean brush-less DC as well) and the second or third hand industrial motors and small hobbyist variants, for reasons that seem rather trivial.
I wanted a to select a motor that had at least stator cooling (shaft cooling would be awesome, but I don't know if there is any way to acquire those outside of parting out a Tesla, (which I read is permanently affixed to its reduction gear/differential) Which is looking to be both too large, and unsuitable for my application.
I wanted to try my hand at a differential steer/differential drive. using 4 independent wheels and...for lack of there being a good/cheap/available motor. I was wondering if anyone had any thoughts/cautionary tales about using hobbyist RC motors stacked into planetary arrangements to drive a lighter weight vehicle directly. something like a hub motor arrangement (though my project will be a tad different mechanically)
I know of 2 issues with this. firstly, its wasteful volumetrically to have 5 or six motors where 1 large motor would have worked. this is irreducible but I figured it may offset some of its shortcoming because the individual motors are pretty high performance for their weight and have good balancing and performance properties. The second issue is that RC motors of the power you'd need to power a vehicle, even working 6 or 8 in tandem per wheel, need to be beefy indeed. 5 or 6kw continuous at a minimum, if you want a vehicle of even modest performance.
there is a third issue about vehicle dynamics at low speed causing excessive wheel hop. I think the only way to reckon the correct wheel geometry is through experimentation.
Here's the stuff I would like some advice on: Never attempted regenerative breaking with a bldc motor and controller of the hobbyist type...doubt many have either. I also know many prefer these motors to be very (overly) simple, lacking hall sensors and encoders etc... and the controllers themselves may prove unsuitable. Anyone have any thoughts into this sort of arrangement?