mechanical load sharing of coupled motors

strantor

Joined Oct 3, 2010
6,339

Wendy

Joined Mar 24, 2008
23,080
Combat robotics has done quite a bit of research on the subject. I remember reading some of the heavy weights (500 pounds and bigger) drawing over 500A stall current before moving. There are a bunch of online stores to support the hobby too.

shortbus

Joined Sep 30, 2009
9,762
Am I that transparent? Right now I'm in the middle of reading microchip AN857 "Brushless DC Motor Control Made Easy". You may have noticed last week that I was asking a flurry of questions about brushed DC motor control. Now questions about motors. That's because I had just taken for granted the motor. now I've taken a step back, seeing what's out there, and where to go from here. good thing I hadn't ordered any parts yet, as I nearly had my whole controller designed. I am weighing all my options... so why, other than the reasons which are right now apparent to me (need 6 FETs/FET banks, need to incorporate commutating logic), would it be much harder and more expensive to make a brushless controller? I'm only on page 11 of the AN857 and have other docs to read so really don't have a good idea what I'm getting into yet. Assuming I don't blow up my controller first try, I can actually find a brushless motor of comparable (actually slightly higher) HP than the brushed ones I was looking, at for about 50$cheaper, so I would save money. This goes back to what I've said a few times in your threads A VFD using a DC input is exactly what your describing. It also has the advantage of not needing the Hall sensors, if you use a "sensor-less vector" VFD. Thread Starter strantor Joined Oct 3, 2010 6,339 This goes back to what I've said a few times in your threads A VFD using a DC input is exactly what your describing. It also has the advantage of not needing the Hall sensors, if you use a "sensor-less vector" VFD. Yes, the circuit is functionally the same; I would be building my own VFD. the main problem is the voltage (as I've said a few times in response) If I wanted to use an off the shelf motor, I'd have to have it rewound for a lower voltage, or increase my battery pack voltage. having a battery pack on the order of hundreds of volts isn't really cheap or practical from my hobbyist perspective (I'll be using deep cycle marine batteries, at 12V each). I am finding 48V brushless motors a lot easier to come by than 48VAC induction motors. for example I can get this motor (just the motor) for 390$. Where can I get a 48V 15hp induction motor that only weighs 22lbs?

or if I somehow developed deep pockets, there's this one:
http://www.ebay.com/itm/ME1012-Brus...844?pt=LH_DefaultDomain_0&hash=item3f0b34de74
72V, 32hp, 92% efficiency, 35lbs for 82\$.
A 32hp induction motor is going to weigh hundreds of pounds.