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Battery Charging and Electronic Technology => Learning Electronics => Topic started by: ted.lowe on May 10, 2012, 12:56:04 PM

Title: D.C. Motor Torque/Speed Curve Tutorial:::Understanding Motor Characteristics
Post by: ted.lowe on May 10, 2012, 12:56:04 PM

Excellent overview/refresher!

http://lancet.mit.edu/motors/motors3.html (http://lancet.mit.edu/motors/motors3.html)

Title: Re: D.C. Motor Torque/Speed Curve Tutorial:::Understanding Motor Characteristics
Post by: miodrag.zubic on May 12, 2012, 02:59:43 AM

... For those who wouold study the characteristics ... it is good to note that this write-up is for (as they say at the begining) permanent magnet motors. Series-wound ones (which are used in virtually all conversions) have a different (non-linear) characteristic. Theirs is almost like 1/x function - see below. In theory, at no-load speed would go to infinity. Practically, applying rated voltage to unloaded series wound motor makes the motor go crazy fast until rotor starts coming apart. I still have memmories of my students running for a cover when that accidently happened during a demonstration in a class I held.
Similarly, stall torque (at rated voltage) is extremely high. It causes motor current to shoot so high that it would likely damage the commutator in seconds if not even sooner than 1 sec.


http://www.engineersedge.com/motors/dc_series_wound_motor.htm